Right now I have an LG4. It will be getting swapped for a 355. What would be better for an all around mix of power (350-400 hp?), torque (around 400 lbs/ft), drivability, and gas mileage, the CC Carb or a TPI? If TPI would be better, will one off of a 305 work as long as I change to 22-24 lb injectors and a 350 chip?

Thanks for your help!
Mark

------------------
1986 IROC LG4 "Bone Stock" (for now)

 

To support that level of power from TPI at the least you will need a fully ported base (or aftermarket) and aftermarket runners. In other words, at least $500 to a grand, then you will need to do something about injectors and a PROM burning set up, as welll as a scan tool preferably to really get it dialed in.

With CCCS you need a $150 manifold. The only 'problem' is that you cannot burn chips for the CCCS computer, thus you are stuck with the stock spark curve. HOWEVER, it is my contention (as well as several others) that CCCS does NOT need a computer controled distributor to be happy. A regular distributor should work as long as you run a signal from the tach wire to the distributor reference signal on the ECM. There *might* be some filtering needed, but nothing difficult at all. And then you could tune the advance curve the old fashioned way with springs and weights. And still have the blazing economy and emmisions of CCCS.

As for economy i say it is a near wash unless you are VERY good at burning chips. My 85 could get 26mpg on the highway and had to be in the 300hp range. My LB9 vert has only hit that number once. Basically, you cannot beat the efficiency of the Q jet primaries for cruising, especially when there is feedback keeping that mixture dead on for you.
...ed

------------------
Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

That sounds like sound advise. The way I now understand it now is that it should be easier and more wallet friendly to stick with the CC Carb with this power level. Now, about the distributer thing, has anybody done this? If not, if I could get some guidance on how to do this, I could do it and report back on it. I am fairly new to this computer thing and what Ed said to do to the distributer just went WAY over my head. I can do non computer distributer stuff, but the part about using a non computer distributer with a computer I just didn't get.

Mark

------------------
1986 IROC LG4 "Bone Stock" (for now)

 

Actually this isnt limited to any car in particular, any computer controlled car should be able to work fine with a regular distributor, all the ecm is looking for is an rpm signal. I havent yet tested this theory, but a friend of mine says he did with his 85 LB9 and it worked fine.

 

With no other mods, and just replacing the Qjet w/ TPI, I shaved a full second off my 1/4 mile time (16 -> 15 seconds). Fuel injection is a little more costly, but I think its well worth it.

------------------
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'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
3.73 Posi
4wheel Disc Brakes
Summit 1-5/8" headers, 2.5" Dynomax catback.

Best 1/8: 9.519@72.74

'97 Bonneville SSE

 

Port fuel injection, when tuned properly and with matched components, is far superior to any carburetor in terms of efficiency, driveability and power production in a street car. Gasoline direct injection (GDI) is even better. Notice I said "when tuned properly with matched components". Problem is, it takes more $$$ to optimize EFI, and even then, I'd say 80-90% of EFI cars are in some state of "detunement ". Just my $0.02.

------------------
1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley AFPR, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Ruger P95DC, hot wife, new oil filter, thick rubber floormats, no cats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

Thanks for the input! It seems to me now that since I already have an Edelbrock Performer intake on the car, going to a 350 with the carb "could" wind up costing me about $1000 less than buying and setting up (injectors, throttle body, bigger runners, etc.) a TPI to support the same power level. Am I right assuming this?

Mark

------------------
1986 IROC LG4 "Bone Stock" (for now)

 

Yes, but with tpi comes low rpm torque (with correct runners/base) that a carb would have a hard time matching. Also my LB9 starts right up in -30* winters of chicago...I have had some trouble getting carbed cars started in this weather. The computer can be a major pain in the @ss when swapping motors, but once set up the low end force of a good 350tpi is awesome.

 

Sorry, just trying to keep this debate full of loaded and opinionated answers. Believe me, i know the strengths of both systems, and if i was starting w/ a CCCS car, and i wanted a mild 3-400hp engine, i wouldn't even consider a TPI swap for a second, there would be no point. If you have a later TPI car then sticking w/ it makes sense to keep it (note what i drive now), but TPI is not the superior system, especially if you have to ask the question if you get my drift. Making a hot TPI car truly better than a CCCS car will require some amount of knowledge, planning and most importantly, $$$$

------------------
Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

This is one of my gameplans with CC Carb. Do you remember the Miserly Mouse in CHP? On 87 octane they made 390ish hp and 420ish lb/ft of torque. To my recollection the 355 had 8.7:1 compression, Comps XE268 cam, Vortec heads, Performer Vortec manifold, and I don't remember what else. Would this or a similar setup be compatible with the computer? I would also add a 3.42 posi rear, TES cat forward system (I already have a Flowmaster Force 2 cat-back. Would this put me at a good 60 foot time? I am really leaning toward just keeping the carb, I have no experience with fuel injection so I think I would be better off sticking with what I know. I just can't see the gains (what they may be) being worth that much investment of going to TPI. Dollars per HP seems to be much better with the carb.

Mark

------------------
1986 IROC LG4 "Bone Stock" (for now)

[This message has been edited by wiggy'sIROC (edited August 22, 2001).]

 

Ed and all,
I wasnt trying to say that a carb setup is bad. I was referring to the design of the tuned port injection to produce low rpm torque by creating high intake air velocity. Im not saying that the LG4 or L69 are bad engines, but let me say every one I personaly have lined up against has ended up in my rearview mirror.
peace

 

You hear that all the time about how much better FI is than carbs...

I have never heard of anyone truthfully getting more than 350 HP out of a TPI, and even that was after heavy modification. That system is simply too limiting. It's misleading to talk about what FI in general is capable of, and then to apply that to a specific system; it's just as misleading to say that carbs produce more HP, and then attempt to apply that generalization to, say, the one that comes on a 2.8 in an older S truck.

For some actual dyno numbers, there is a post on the Motor swap board where a guy took his TPI 350 and put headers, some kind of heads, SLP runners, and a handful of other stuff on it (most conspicuous by its absence is the choke point in a TPI, the intake base); and got 211 RWHP and 282 ft-lbs of torque. Not bad at all, considering the combo. On the other hand, my L69 305, fresh short block, with a set of old junkyard 186 casting "double-hump" heads, a Comp XM264HR, 1.6 rockers, and Edelbrock TES, did 213 RWHP and 282 RW ft-lbs. And, he doesn't say whether his emissions accessories are intact; mine are. My car passed California smog 3 weeks ago, and has all the emissions stuff (AIR, EGR, cat, etc.) hooked up and operating.

So now which looks better?

That said, if I hadn't been stuck with CA visual testing where they have a book that they look up what devices your car has on it and go find each and every one and make sure they're the right part # and are hooked up correctly, I wouldn't have used the CC carb. And I probably would have been able to get quite a bit more out of it with a Holley, and some other distributor. The CC carb setup is definitely not my first choice of how to make the best-running motor, though it obviously has some degree of potential.

On the other hand, if I didn't have to worry about visual inspection in CA, and I was willing to spend some money, I might have put an Accel Pro Ram and DFI on the 400 I took out of the car in order to put this smog 305 in. I feel fairly sure that I could have gotten more out of that than with a carb, with enough tuning.

So what's your budget? And what are your local emissions laws? I can positively state that you're absolutely not going to get 400 HP out of a TPI without nitrous or SC, and most likely not even anywhere close to 350. The same goes for the CC carb: you'll be hard put to get much past 300 HP out of that setup as well. Put a MiniRam on it, and then you might; or some other FI, and maybe you will; but for 1/3 the cost of that, you can use a Holley carb and a better intake, and get the kind of power you talk about in your question. What's the highest HP car you've ever driven? Do you have any idea how much needs else to be done to actually use that much power in one of these cars? Don't forget, you're asking for nearly tripling the power output of your engine. And, if your goal is a 400 HP 350, you might as well forget about driveability and gas mileage. You don't get either of those things out of a 1.2 HP/cu.in. SBC.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

Honestly, the fastest car I ever drove was my father's 94 Z28 and he gets outstanding mileage too. That is one of the reasons that I brought up this subject, the late model FI cars are fast and get better mileage that most carb'd cars and that is part of my all around vision. I want to get into the low to mid 13's without nitrous and be able to drive the car in town. In the county I live in there are no emmission requirements, but I am in the military and I never know when or where I am going. I have some issues with my smog stuff but that will be in a different post. Thanks for the info and opinions and keep them coming!

Mark

------------------
1986 IROC LG4 "Bone Stock" (for now)

 

WIGGY!!! finally another Idahoan on the boards

 

I think we are all missing the fact that in STOCK form every tpi (maybe not 86 LB9) will outperform any STOCK carbed thirdgen. I do agree that this may have just been because GM wanted it that way. They gave the Carb/tbi cars weak cams and low compression (except L69-9.x/1). It is my opinion that if you have one of those cars its pretty easy to get them performing along side stock tpi setups, provided you dont mind changing out the cam. It just might be a lot easier for those of us who start out on top. If extreme horsepower is the argument, well I think there cant be any, until I see someone with THE STOCK INTAKE on their carb setup generating the power a stock tpi setup can put out. If you want to compare you have to be fair. Ill be the first to admit that all the big boys use carbs, and efi guys always will lose to prostock.
just my opinion

 

85:

My car does have the stock intake on it. And as shown by the numbers, it's producing the same power as a 45 CID larger engine with a modified TPI intake. My mods are exhaust, cam & heads; the same things that pay off on a TPI motor, or TBI for that matter.

You're right about these engines in their totally stock trim though. Alot has been learned over the last few years about how to make an engine produce power in spite of ever-tougher emissions and economy standards. There's no way to make a carbed engine that will provide the same level of all 3 of those important things as a FI engine can be made to: power, emissions, & economy. The accuracy of the controls just isn't even close. But that's a far cry from saying that TPI is better than carb. The later F-car performance FI systems are so far superior in every way to TPI that it should be obvious what a limited system TPI is. It's good at what it does, but it's maxed out, no room for it to grow.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

my original point is that a tpi setup will give you more low end torque and better drivability. I promise if you took any CC Carb car with any amount of mods and run it on a dyno, then put the tpi setup on the same engine with the same mods you will have more low end torque! We arent talking about hp, we are talking about what matters-torque.

 

I would sacrifice some top end horsepower for bottom end torque. It will probably never see more than 5000 rpm. In an earlier post I had mentioned some of the internals the engine would have. Would they work with TPI (minus the vortec heads)? The car will sometimes see some dragstrip time but primarily it will be a semi daily driver with time SCCA racing on my Air Force base. Does this throw another wrench in the decision?

Mark

------------------
1986 IROC LG4 "Bone Stock" (for now)

 

85 and wiggy, did you even read my last post?
The 350 in my 85 had all the torque and driveability anybody could ever need. Why are you harping on this building low end torque issue so much, you act like a carbed car comes out of the hole like a civic. A 3-400hp small block w/ carb will easily make 350-400 lb ft of torque.
The perfect example would be to look at the guys w/ ZZ4s under stock TPIs. As far as i've seen they tend to make less power and are lucky to get close to the torque that a ZZ4 is rated at w/ a carb on it. And i've driven carbed ZZ4s and they are as smooth and driveable as anything out there. I don't see how TPI could help, or why you'd even want to try to change it's low end characteristics, it's hard enough to hook as is.

 

Since it is coming right down to it, I think I am going to keep the carb and the computer. Reasons: 1)I know carbs and don't know TPI 2)Money . I thank you guys for all of your input.

Ed,
Do you think the combo that I partially mentioned in a previous post will be close to what I want and still retain the CCCS? I will try to figure out how to try that distributer thing you were talking about.

------------------
1986 IROC LG4 "Bone Stock" (for now)

 

Give me a second to pipe in here.

Granted, my only FI vehicle at the time was my '99 Hawk, whose LS1 engine is kind of doggy off the line. BUT:

My 84, with the ZZ4 and completely intact CCC system, was much easier to drive, and had all the low end torque you could ever want. A friend of mine borrowed it and started off in 3rd gear once by accident. Try that in an LS1 without serious footwork on the clutch and it will stall.

It has 27" tires on the rear and had 3.23 gears in the back, and could roast 'em easily with a small (~1250rpm) dump. I changed to 3.89s and it was an absolute animal in 1st gear; stomping the gas from a dead stop resulted in tire spin the minute the secondaries opened.

Granted, if you're USED to the low end torque TPI produces, a CCC system will probably feel a little soft on the bottom. But consider:

1) The LT1 and especially the LS1 produce less bottom end power than stock TPI on a modified motor.
2) The carbureted system is actually a good bit easier to launch, since it has a little less low end torque. Why on earth do you want 380 ft-lbs of torque at 1000 rpm? You'll never hook that on the street and you'll be breaking parts left and right at the track
3) I went to a gathering a couple years ago and my car had *the* best city mileage of all the thirdgens there (19mpg) with the 5spd and carbed ZZ4. Most of the cars there WERE TPI. I didn't have close to the best highway mileage though, all the LO3s had me beat there
4) To make the kind of HP you're talking about, don't even talk stock TPI. Start talking superram or miniram, new injectors, new TB, etc... I am pretty well aware of the issues since I'm building a 91 SD TPI Z. And if you go to the miniram? Well, I don't think you'll be making MORE low end torque than a CCC system (of course, you'll be hauling *** at the track, but the question was low end torque, n'est ce pas?)

Stock TPI's main advantage over the CCC carb system is (too much IMO) low end torque, and possibly starting in subzero weather. I've never had one bit of trouble starting my CCC car nor do I expect to. Like Ed said, it's called knowing how to manipulate the choke. Switch to a SR or MR and you pick up some other advantages but lose in the torque department.

I happen to like my CCC system. The ECM is dumb as a post and knows nothing about what's really sitting under the carburetor. Yet it's smart enough to maintain fuel economy in part throttle conditions that is pretty good.

One of my goals is to see how much I can get out of this system before it serious starts suffering at the track or driveability. I'm betting that I can crack 12s with enough mods and still be able to drive it on the street like a stock LG4.



------------------
"Beware he who would deny you access to information, for in his heart, he dreams himself your master"

'84 Black Camaro ZZ4 M5 (V-6 in a former life) -- street beast
'91 Medium Blue Metallic Z28 A4 (UB-HSTRY's old ride) -- currently broken
'99 Navy Blue Metallic Firehawk #120 M6 (99.44% stock) -- daily driver

 

I have a similar setup as to what you're wanting to run. Main difference is I'm using a 750 vac sec Holley instead of a comp controlled carb.

But anyway, you don't need to worry about lowend torque with a decent vortec headed engine with a reasonable cam. I can roast the tires all through 1st gear with no powerbraking required. Just get on it hard enough from idle and up in the smoke the tires go... More lowend torque is the last thing you are going to need. I'm with Ed there, any decent 350 isn't going to have problems with torque. Maybe some anemic stockish 305s need the TPI to get decent performance but that is not the case with a decently built motor. Stock TPI is a worthless POS setup to put on any decent 350.

Driveability wise you're also not gaining anything with TPI over a well tuned carb. My 87Z with the carbed 350 is far more enjoyable to drive than my 86 IROC with the TPI is with the 87Zs instant throttle response and plenty of low end. Frankly I don't know where the whole poor driveability crap comes from, I certainly don't have any problems in that department. Maybe in some really cold start situations the TPI would be better, but in the winters here both cars start up fine, slight advantage to the TPI car but I couldn't care less as it's not a big enough difference to matter...

My vote is stay with the carbed setup or switch to something like the SuperRam or MiniRam if you need a FI setup. The stock TPI will just choke your motor up top while only giving you more useless lowend torque.

------------------
Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited August 24, 2001).]

 

As for highway miles ive gotten as good as 27-30mpg on the highway w/ 3.27 gears. I have nothing against carbs! Evey car I have owned before my 85 had a carb. I dont miss having to mess with the stupid carb every six months, or working to get it started when its cold. Something else that wasnt yet mentioned is the throttle response tpi give you. And I still am gonna say that with tpi you will have a much lower torque peak. The fastest car I have ever been in was a 69 camaro with a 383tpi setup. This setup WAS modified with runners, mild porting...but the car ran 12.9's all day with a 3.08 rear. If you want your car to FEEL fast then you want torque...and who the hell says you can have too much torque?!? TORQUE x ENGINE SPEED/ 5252= HORSEPOWER. Lets face it torque is what turns the wheels, torque throws you back in the seat. As far as most people are concern torque is power!! (why not have more with tpi?)

that said I can understand the limitations of the stock system and do understand that it does cost a lot to convert. It can be fairly cheap if you go with a used setup and port it. Im not saying that it wont be a headache to put in, but I think you will be happier with the end result.

peace

 

Never had that problem. I have a rebuilt Pep Boys qjet, and after finding that I blew the needle off the seat with too much fuel pressure, I pulled the whole thing apart, rebuilt it on my dining room table, slapped it back in the car and was good to go. How many of you can remove your TPI in less than 5 minutes? Cold starts? I have had carbs that have cold start problems, but my current one doesn't. LEARN TO SET THE CHOKE!

I don't understand what the issue is with throttle response. When I stomp my foot to the floor, the car GOES. The only issue I have is the ~1 sec delay for the secondaries to open completely if I stomp on it from a 3000 rpm cruise... which I rarely do. I still need to fix that by changing vaccuum cans.

I will say one thing... throttle response and pedal feel are two completely different things. And the pedal feel of TPI just *sucks* compared to a carb, or to my LS1 (I guess GM figured that out eventually with FI).

I bet it could have run faster with a less restrictive setup. MR, SR, carb, you name it. Stock TPI is exellent for stoplight to stoplight racing. Not so good for 1/4 mile. I've gotten my *** beat bad by a modded L98 from a light in my Firehawk... but only to 55 or so MPH. When I race one at the track, it had better get a hell of a jump on me if it expects to stay in front past the 1/8th.

You don't need to recite the formula for HP, I think most of us know it. The issue is not torque, but LOW-END torque (what most people think of when the say torque -- after all, HP is just "high-end torque"). And you sure as hell can have too much low end torque. You ever try and launch something with 400+ ft-lbs at 1500 rpm on street tire? We *are* talking "true" street cars here, right?

Besides, I don't care about feeling fast. I want to BE fast. I don't care how fast the car feels, if it runs a 15.x it's slow. Just ask people who switched from LT1s to LS1s... they all said "This damn LS1 feels SLOWER than my LT1, why the hell is it running faster in the 1/4?". I'll give ya a hint... the answer wasn't low end torque.



I'm happy with my carb. We'll see when I get my '91 running if I feel the same way about TPI. And it would be a headache to retrofit... don't forget converting to an electric, high pressure pump which requires new fuel line fittings, etc...

I'm interested in going fast for less cash. Considering how weak the factory driveline is on these cars, the less $$$$ I spend on the engine, the more I can afford to splurge on a T56 and a 9" rear. Speaking of which... anyone who doesn't think carbs can make low end torque, I'll show you pics of what happened to the spider gears in my 10-bolt on the second-ever run at the track.

 

edit: below is my original reply but it is long and weird. To summarize:

There are 4 or so people responding in tyhis post who have had healthy street engines w/ carbs. At least 3 of them running CCCS. Notice how all of us are saying the same thing, that we had not a single complaint for driveabilty, cold starts, or low down torque. IMO that says it all. You can bench race and talk theory till your blue in the face, but at the end of the day the guy who is driving that combo KNOWS what it will do.

It's not about too much torque (although there is a such thing cuz torque is what breaks things 9 out of 10 times, try running your buddies 383 TPI through a stock 3rd gen 3.08 ten bolt and it will shatter like like fine china.) it's about 'enough' torque. As a few of us have now piped up, a street 350 will make more than enough torque to drive and get you out of the hole. And will make vatsly more power than a stock TPI. I wish i had the time to search the boards, but i know i've seen more than once that guys w/ a ZZ4 under a stock TPI couldn't match the HP or torque that the engine was rated at with a carb.
As to your throttle response argument, in my 85 (w/ 3.08 rear) I could break the wheels loose cruising in first and just tapping the gas pedal at any speed. Q jet primaries are as super efficient as carbs get, the slightest crack of the throttle lets in a little more air which the triple venturi primaries have no problems converting to the proper fuel mix instantaneously. Did i ever tell you the story of the time i drove w/ NO accelerator pump in my 85s carb. I kept having TPS issues, and while i was sorting it out i got sick of getting the acc. pump to behave while putting the airhorn back on, so i left it out for some testing. And you know what, it still had decent throttle response. Why, cuz street 350 has no problem pulling air at any rpm, and the q jet primaries can do anything if you move air through them. Granted if your carb experience is limited to low HP wheezers then i can see how your opinion is biased. Low output engines can tend to be soggy w/ a carb b/c they don't move enough air fast enough to let a carb do it's job.
As to the cold start issue. In my 85 it was never a every 6 months or seasonal choke adjustment. I set it once (after i rebuilt the carb) and never touched it again. Like i outlined above, since my engine pulled enough air to effectivelly utilize the vacuum increase from the choke plates, coupled w/ the effiecient primary design. The 83 grand prix LG4 i was toting last year did need a summer/winter change, but that was as simple as loosening 2 screws and moving the choke 2 notches. And ii actually tightened it down in summer and loosened it in winter which makes me wonder if the priblem wasn't a goofy choke coil cuz it's problem was cold starts in warm air, it needed more choke than the winter setting would allow. That could have been coupled with it's anemic airflow needs.

I don't know, this debate is pointless, it's readily apparent that you are biased from some kind of bad carb experience (or some kind of great EFI experience like your friends 69.) The bottom line IMO is, if you have a complaint about a street 350s driveability or cold startability, or low end torque then you just don't know how to tune it. Properly done it can do anything EFI can do that you need on the street.

[This message has been edited by Ed Maher (edited August 24, 2001).]

 

To answer above question...Yes I have launched a car with 400+ft/lbs on street tires. The car is a 66 olds 442 with a built up 455, 4 speed manual, and 355 gears. Yes, CARBED, but with a holley 750 double pumper, offenhouser intakem, and HUGE cam. Wheelspin is only a problem unless you make it one by dumping the clutch too fast. the 69 camaro I spoke of formally had a carb setup. It was all converted to tpi when a the old 350 was rebuilt and stroked to 383. With the old holley and edelbrock intake the 350 ran high 14's with the same gear/heads/trans. The change cost a lot, for the tpi alone but like i said its worth it once done right. and im never gonna understand why you think torque is undesireable, most people go looking for it!
peace

 

Wiggy- to answer your question, yes, you CAN keep all the computer controlled stuff on the engine even if you heavily modify the motor with larger displacement (350, 383, 400, whatever), hotter cam, opened up exhaust, etc. Drop me an email and I'll give you the straight poop on how to do it the RIGHT way (without defeating any emissions stuff or throwing check engine lights).

If anyone cares to actually SETTLE THIS ARGUMENT I am available with spare QJet, distributor and nntake manifold in hand to travel anywhere within 3 hours of Philly and do a little back-to-back testing. Anyone want to bet against me??

Here's how it's gonna stack up on a mild 350 TPI Motor: I'll lose to the TPI by about 25 ft. lbs at 2000. By only about 10 at 2500 and we'll be dead even by 3000. After that my QJet will pull ahead pretty quick and I'll be an easy 30-35 HP ahead of the TPI by 5000, and the gap will get bigger from there up.

 

Maybe I am being a little too "loaded and opinionated" Maybe I just enjoy starting my car from inside my house with the push of a button when its cold. Im sure in this case the carb is the way to go because of $$$, and Time. Who here has the fastest CC carb car and what does it run? Like I said earlier I had never SEEN anyone out of 15's, but now Im curious.
peace

 

The TPI has a very narrow torque band, which is part of the sacrifice it makes to make that low end peak torque that everyone talks about. Personally, I think its a useless tradeoff. Ill write a more lengthy reply in a little bit.

And I too have a carbed car (although not thirdgen) that gets excellent mileage, starts great, definitely does not lack torque anywhere, and I have not rebuilt the carb in 10 years so I dunno what all this adjusting stuff is. I have changed the fuel metering, but I cant control changes in the gasoline or when I change parts on my car

 

Ok, time for another reply.

What everyone is saying about the TPI is right. What good is a whole bunch of supposed low RPM torque? All it does is break the tires loose, and its much harder to modulate the power when its at a low RPM. The powerband of the TPI also sucks, its from about 2500 maybe to 4600 and then it falls off like a rock off a cliff. Thats a whopping 2100rpm powerband, which is pathetic. Area under the curve is what counts, and if your torque doesnt kick in until 3000 but carries to 5500 and doesnt drop off like a rock, you already have an advantage. Thats how the LS1 works, not much power low end but a very wide powerband with lots of area under the curve. Carbed cars tend to head more down that route even though they are not as precise in fuel or timing as an FI car, but there is generally more peak power with the carb so the dropoff you get at the ends doesnt hurt it a whole lot. I have been in and worked on hard starting carb cars, but adjusting things properly and keeping dumb mechanics that arent real knowledgeable about carbs away from them afterwards tends to cure them of any future problems. Carbed cars have been around since day 1, and were pretty much in use until 1986ish, so I'd have to say that 86 years (many of which there were FI systems) of people using them every day and having little problems with them just about throws any argument that carbs are crap right out the window.

 

I'd tell you what mine runs, but it keeps breaking things. I *will* tell you this, it runs low 14s at least, because it was able to mostly keep up with my 'hawk on the street. Considering I don't have the off the line trouble with it that I do with the LS1, and a few more mods have been done since them (modified secondary air valve, 3.89 gears, 6 speed, and 1 3/4" headers), I'd be willing to bet that it's a 13 sec car in the right hands. It just remains to be seen if those are MY hands .

 

You put a t-56 in? Man that would fly. Keep everyone posted if you ever get to the track.
Anyone else running 14's?

 

My 85 ran 13.9 @ 99.9 with the following:

357ci, 218/218 .458/.458 cam, JUNK 1978 305 heads, edelcrock performer intake and TES headers including the LG4 style 2.25" Y pipe with a 3.08 one legger rear. Stock LG4 carb, distributor and chip. Also had the stock 1500 rpm stall converter and my tranny would slip the 1-2 shift pretty badly.

I ran MANY 2.0 60's, and anything higher than a low 2.1 meant i screwed up the launch.

With posi and gears i would have EASILY ran in the mid 13s range, like i said, i was getting 2.0 60's on a one legger nursing it off the line. With a converter and heads on top of that it would have been 12s or damn close.

And in case you missed my earlier posts, this is the car that consistently got 26mpg on the highway and would start all winter long in state college PA in single digits and below on the first turn of the key.

Like i said, it's well and good to theorize about how the torque of TPI is nice, but the fact is quite a few of us in this post have driven the combo he is asking about and loved it. Even though i know and understand TPI as well as most anyone i wouldn't even consider swapping to TPI on a CCCS car.

 

Ed, those are some damn fast times. What is the fastest you have ever seen a 305 carb run? For the sake of argument I see L98's run 13's all day at the track (with mods).

 

Not to fuel the fire anymore
Just a few observations, madmax: You said the 2100 ROM powerband was puny, then quoted a powerband of 2500 rpm as great? Thats a gain of 400 rpm?! Sure it's up top, and its going to be making more "horsepower" and thats what the general populace looks for. However, to be scientific, Torque is the force which rotates, a vector that is the axis of revolution (perpindicular to the side of the wheel through the center) SInce a force creates accelleration, Torque creates a radial accelleration, thus causing the wheels to spin. The friction of the rubber vs pavement with the weight of the car creates linear motion. So if you exceed the force the rubber can grip at, you are losing power. However, low end is just as useful as high end, for manuals, for automatics, low end is almost necessary, uless you have tons of high end. Why, traction! With a clutch you can control how much power is making it to the ground, if you have a high end power car, you can keep the rpms in your powerband for some time! Low end, you can limit the power going down. Automatics though are a different story. With no low end, the car will dog the whole way to it's powerband. There is no way to keep the motor in the powerband. So you want the powerband low so you aren't wasting valuable seconds to get to your power.
I didn't really mean for this to be a manual vs automatic arguement, and really it isn't. You just need to keep focus of what you are doing, and how you plan on driving it! If you really really really want HP, you could lower the compression, use balanced aluminum parts, and try and lighten the rotating assembly as much as possible, throw a few turbos on, new cam, etc, and suddenly you have a car with a powerband from 6500 rpm-8000 rpm. Great, gobs of HP since you are over 5252 rpm, but where'd the torque go? exactly. Build the car how you see fit, but just stick to a goal. Once you set a plan, it will cost you $$$ to change it 1/2 way through the project.
Good luck, let us know how it turns out!
Corry

 

With elevation corrections. CCClg4 with 270H 15.8.
Same lg4 non cc qjet and dis 15.2.
82 Firebird 200c tranny 2:73 gears.
SSC

 

First as to the fastest 305 carb that i have seen. That'd be a guy i know with an 87 monte carlo SS. Stock it ran 15.0s (L69, stock 3.73s). With long tube headers, a GMPP intake, a shift kit and thats about it he was running 14.3s. With a comp 280 magnum (way too much cam for a 305) he was running 14.0 @ 100, with the right cam it would surely have been faster. Also worth noting is that he had 140k miles on it when he did the cam swap and the thing smoked like no tomorrow, yet it still put down good power.

As to L98s running 13s all day, i know my 13s don't prove that much, you really have to look at the junk i was using and still made 13s. You seriously couldn't get a worse head (except swirl ports) than the heads i had on that thing (it was a cheap longblock i bought locally), and the 3.08 gears and tight *** converter were huge drags too. Also, i had to have a very easy smooth foot off the line or i'd roast that one legger, posi alone would have dropped me a few tenths just cuz i could have applied more of the LOW END torque that i had off the line, hehehe. L98 cars in the 13s most certainly will have at least 3.27s stock and also, 083s are not a horrible head for stock either, in fact i think they are one of the better factory castings (excluding vortecs)

 

For racing, not true. With an auto, just buy a torque converter with the proper stall. With a stick, you've got a "user adjustable" torque converter, i.e. the clutch. Either way it's not a problem.

For driving on the street, you need some low end, yes. But dammit, you only need so much! There is no point in sacrificing up to 50hp from 3000rpm to 6000rpm just to have an additional 50 ft-lbs at 2000rpm! Once you have "enough" torque, you just don't need anymore, and it makes SENSE to trade some of that low end TQ for high end HP.

Who cares if you have 600 ft-lbs at 2000rpm or 450 ft-lbs? You'll NEVER hook either of them on the street anyway, and at the track, the 600ftlb car is going to be breaking parts left and right on the launch. And if you don't hook up there either, all that extra torque is going up in smoke! That is NOT the way to win a race!

I have yet to see a properly built motor under a carb, CCC or otherwise, not make "enough" torque to drive it reasonably on the street, assuming the cam generates enough vaccuum (but, IIRC, TPI will go ape**** quicker than a carb with low vacuum). It's just not an issue with a motor with as many cubes as a 350+ small block.

FYI, I drove my car a couple times between the gear swap and the tranny swap, and let me tell you, it was a challenge grabbing 2nd before banging the 6k rev limiter. And shifting into second at that point got the car SERIOUSLY sideways. And this was running on open headers which are known to rob low end torque. The biggest driveability problems were keeping the car straight and trying to think over the noise!

 

Oh, and FYI... take one look at the GMPP catalog and flip to the "350HO Conversion kit" for 82-87 Camaros. GM got a 13.7 outta their test mule with ALL emissions equipment intact, stock auto tranny, stock converter, and stock carb + rods.

I expect that my car can beat that by at least a couple tenths.

 

Ok, yiu got me there, I am personally using a 1987 T/A with an automatic, and I cringe at the thought of putting a high stall speed converter on there....lots of added heat, and terrible gas milage :eek However, I know at the SWMG most of the cars we dynoed, even mine (as crappy as it may have been running) had a nice flat torque curve ut till around 45-5500 rpm. So if you generally speaking towards these motors, if you have 600 ft-lbs of torque at 1250 rpm, you probably got at least 570 ft-lbs of torque at 3500 rpm. Maybe some mods might edge up a little here and knock off a little in other places, but the base has a pretty flat curve. I have heard of this realativily flat curve from several other l98'ers out there.
Even still, you still proved my point on what you said. The end of my post, I said you need to keep focus, decide what you are plannign on doing with the car, and do it, do not try and make a car that is going to take on everything at the drag track, and then try and road race it. Do not try and make a championship road race car, and then daily drive it. If you want a HP car, then by all means, grab the turbos, the custom transmission to take advantage of the rpms, and the lighter lower compression rotating assemblty, but then don't complain when this turbo V-8 HP monster is getting 5 mpg cause you have to keep it at 6000 rpms!

On another note, I believe mini-rams are also known for shifting the powerband up, due to it's short intake line, which decreases input air velocity. So everyone saying TPI and miniram get better low end, or TPI/MR/SR The SR is the low end torque monster, but the miniram is the higher horsepower route (At least from what I read)

When I decide to go all out on my motor, I plan on moving the power band up a little. But I plan on trying to just shift it up, not side to side, and with a good balanced set of mods, I believe I can get pretty close to doing that, hopefully I'll get up to around 450-500 hp One day when I have money

Corry

 

I think that for most people the numbers (HP and Torque) are unimportant. This discussion can go on forever and still it will come down to low end torque vs high end power. What matters is real world performance. The above post says that GM got a 13.7 (not too shabby) with thier engine. Like I said earlier, Ive seen MANY f-bodies hitting mid 13's with their L98s. The fastest carb f-body ive seen at the track runs 15+ (not counting prostock). I dont know if this is because not many people build them, or if it is because the system is not as capable. All I know for sure is what I have seen with my own two eyes...and they say tpi is faster
peace

 

I actually said it was pathetic (it is) and I didnt say that 400 more RPM was great, but its a decent step in the right direction.

You can explain torque all day long to those who dont know what it is, but its more difficult to deal with low rpm torque than high rpm torque, even with a stall converter that brings the rpms up to the same torque rating on both engines. With absolutely ideal traction, yea it doesnt matter... but ideal is never the case. Ive driven all sorts of cars and the ones with lots of low end torque are much more difficult to get off the line than others. And then with the TPI, the party is all over at 4800 if you are lucky, at which point you shift your 700r4 into second and the engine bogs. Thats where the narrow powerband in the F-body really hits you hard. My car was actually faster shifting it much higher in 1st just to avoid the dropoff from 1st to 2nd.

What was said above about stall converters was correct, even with an auto the car will not bog if you choose the correct converter.

As an aside, the LS1 has a powerband that looks much more like a carb powerband, and the *slowest* one I ever saw was running a 13.6@103 at the track.... bone stock. I *think* thats faster than a TPI car, even with its lack of low end torque, and the wider and higher powerband I have been talking about.

If you want to keep your low end torque and lack of upper rpm power, well go ahead. Just dont go racing any minirammed or LS1 cars with it.

And if you want to increase the powerband just a little... take a look at my siamese intake mod, I think you might like it.

[This message has been edited by madmax (edited August 27, 2001).]

 

madmax, what you are about LS1 makes sense, but why are the carb cars so slow and the LS1 cars so fast?

 

It's probably a combination of a couple of things.

First, the carb cars were not fast from the factory, and never came on top of a 350 to boot.

Second, a lot of people just can't stand the CCC carb system. If I had a buck for everyone that told me to yank it and get a holley or convert to TPI, I'd be a rich man.

Third, you have to understand both electronics and carbs to get them running right. Most people I know my age do NOT understand carbs.

The system is capable in the right hands. More importantly, it is cheap to modify. The problem is, unlike the L98, the LG4 motor is not really a good starting point. But you can yank the long block and replace it with a screamer, and the induction system will still work. There aren't many 406 TPI cars out there still running the stock TPI, but I've seen them with stock qjets and they run fine once the secondaries are tuned ($6 for a set of rods and hangars).

What's really nice about the CCC carb system is that it is STUPID! It doesn't try to second guess you or do any stupid ****. Idle and part throttle, all the ECM knows is 14.7:1, it doesn't care if it is sitting on a 231 ci buick V6 or a 406 mouse. WOT, the computer almost completely butts out of the equation, controlling timing only--the secondaries are completely mechanical just like old, non CCC carbs. Incidently, this is why chips for CCC carbs are a waste of money.

I want my ECM either dumb as a Box O' Rocks (whatever happened to him anyway) or much, much smarter than me. TPI is not either.

 

He's just saying the SHAPE of the curve is similiar. The absolute magnitude is very different.

The problem is the motors that the carbs sit on, not the carbs themselves.

 

Well i'm sorry that you have such limited experience with carbed cars that you won't accept the fact that they do work. Perhaps at this stage of the game you should stick to learning rather than arguing against people who have driven carbed cars that do everything your uneducated inexperienced mind won't believe. Carbed cars have been running better than 15s since before your daddy was born kid and to argue otherwise just makes you look VERY foolish.

 

I understand now what madmax was saying about the hp/torque curves...I also see your point about the ease of modification. The computer on my car can be a real pain in the @ss sometimes. I guess I havent SEEN any fast carb cars because most people would just drop in a L98 and ditch the system. Do you guys see my point though that 13's seem common for L98's and very rare with the CC carb system? Maybe that is why I would think the tpi system is better.

I have no problems with carbs, I jsut think that on our cars the tpi system is better. I pretty much put together the 66 olds 442 I spoke of earlier, and yes he will kill me every time in a race. Another example is Camaro_Z85's post. he is running 14.9 with a carbed 350, check it out.

[This message has been edited by 85transamtpi (edited August 28, 2001).]

 

Admittedly, noone understands the CCCS system, even though it is a wonderful combination of just enough brains and not enough diagnostics. Thats why i still moderate the carb board, i think someone needs to look it over every now and then and make sure jester doesn't tell everyone to swap to holley's. You don't tend to see many fast CCCS cars because so few people understand them, you get the old school gearheads junking them for mechanical carbs cuz they have been taught through myth that CCCS is stubborn (even in 96 when i swapped the 350 into my 85 there were still many under the imopression that it wouldn't work right, etc), and the people with the brains to understand CCCS don't bother and instead stick to EFI for it's snob appeal and 'refinement'. But when you have to make do with what you got as in ron's case, my own, and the buddy with the monte SS i pointed out, you will get great results and amaze people that it could be done. Then we meet critics like you who are not only amazed but actually mock us as if we're lying. Hell, my buddy's monte is a great example of CCCS adaptability. With that giant cam in there he was only pulling like 10-12" of vacuum in neutral. Try getting a TPI to run w/ a cam like that. And i am pretty sure that he still got reasonable mileage with it.

And i'll also say that you must live in a strange part of the country if you think L98s in the 13s are common. I'm not saying that it is difficult to do so, just that the vast majority of people i have interacted with are too busy doing everything wrong (combo/decision wise) to ever make their car run correctly. Just look around these boards and see how many L98s are in the 13s and you'll see that they are in the minority.

 

Alright, 3rd time writing this post, I keep getting wordy, and since no1 reads it all anyways....Short and simple:
1: Low end power is good
2: High end power is good
3: Neither side is really "right", this is more of an opion/question of what kind of motor are we building/budget
4: Power is good
5: I think I have said this in every post, keep focus. Decide what you want to do with the car and do it. I personally like the idea of dropping my C/R getting a big supercharger running say 15 lbs of boost, going into a nice, custom programmed mini-ram (Yes, I will take the higher end power in that case, since a SC will probably work better there anyways) Then have lotsa other goodies in there that will just add to my power. Thats my focus, it may cost more, but I am a computer science major, I like the idea of custom programming my fuel injection system, and I actually look forward to the headache that I will inevitable get from this thing! Also, being a CSCI major, I like being on the cutting edge of technology, even for my car, it may be an 87, but how much has the internal combustion motor changed since even the 30's? I don't feel so bad about the age of my motor. Lastly, I'd like to belive that a high pressure injector will do a better job of atomizing/vaporizing the fuel than some silly carb will, even if that isn't quite true
Those are the only points I am trying to make here, do not read into anything and think otherwise! Very clear and simple. The opinion section below is how I plan on building my moter when I one day have money...only 3.5 more semesters to go! WAHOO! hehe We'll see how it works out...as for everyone else, if you want to build a carb motor, go ahead, I won't say it is worse, or better! Just that I prefer FI.
Good luck with all of your motor buildings, just be ready when I get mine done, I'll see ya on the track, the road track...and the everyday streets. (Yup, I want great accelleration through the motor described above, great handleing, and streetability through a custom programmed DFI...I dont mind rough riding suspensions...)
Corry

 

I dont remember mocking anyone (read all above posts), and I do realize that this is a "loaded and opinionated" question. I gave my opinion and I think I'll let everyone's E.T. do the talking for me. Check out everyone's sig. and look through the arcives. When looking to build an engine check out the fastest third gens at the track (or street or this board) and see what they're running. Build the same engine, you'll get similar results. The choice is yours...carb or otherwise.
this is a debate nobody can win (but it sure is fun to try ).
peace