Hi everyone, I am sure this has been asked before but am curious about your guys results. I did a tpi swap to a carb with an edelbrock rpm performer intake and 600 holley carb. Everything converted fine. The problem is before I could drive the car I got deployed. So I am just curious on if I picked up any hp from the swap. I am aware it will breathe better up top while giving up mpg, drivability and torque. I am heading back home in about a month and was wondering where I am sitting with hp gains from that. More mods are waiting in the garage hooker 2460s and some UMI LCARB, PANHARDBAR, WONDERBAR AND LRCA'S. Any input would be good. I am hoping to get 340 crank hp with a cam and headers added. But for now just an idea where the l98 sits as far as horsepower with just Carb and intake. Thanks guys!

 

I hate being deployed. Whenever I post something I dont get replies very quick. Lol anyone?

 

Seriously guys am I not posting correctly? No feedback?

 

I'll jump in (PS...thanks for serving!). I don't think there is much to be gained just from the carb swap. The cam and headers are really geared towards the low RPM of the TPI setup. So, you still have those bottlenecks to contend with. Headers and exhaust will help. 340HP should be possible, but I bet it requires a cam swap if you stay with the stock heads.

Also, make sure you are getting cold air to that carb (not just an open filter on top). And if you really want to feel a difference, swap out the converter for a good aftermarket one. That will be some of the best money you spend on the car.

 

Thanks, I am aware that the cam is a real bottle neck. A comp cam is in place once I figure out the combo. But the car has a set of hkr headers waiting in the garage, 1 5/8 prim. and 3in collector. I am looking at patriot freedom series heads and AFR heads but AFR is slightly out of my budget but not by much. Now that I swapped to a carb wont my rpm range be slightly higher with the rpm performer intake or is that cam really holding back the motor?

 

I still think your RPM will be limited and I doubt it will make max power at a higher RPM than it does now. Of course, I have never done the exact swap you did, so I could be wrong. I do prefer a carb setup to the TPI. The bigger questioin is the "legality" of the swap. I am not sure what you have to go through to get an inspection sticker.

What are your plans for the car? Weekend bruiser or everyday cruiser? Decide that before you start picking any more parts. Lots of guys on here will be willing to help (myself included).

 

Do you still have the stock cat? Not a huge difference but defiantly a little

 

It will be a weekend car for sure. But most likely I will drive it everyday for awhile when I get back. Until I find me a Silverado and the Camaro becomes the weekend car. The car is registered in the State of Florida. NO EMISSIONS TESTING! But the car will be driven in North Carolina at my next duty station. Since I am military I can keep my car registered in Florida during my duration at FT.BRAGG. The Camaro will get a High Flow cat when I finish up the exhaust. Hopefully a cam puts a fire under that camaro's ***. If not some nice heads will.

 

I put 5-10 just assuming you've done things to the car to make it breathe better at high RPMs.

TPI is only a big limitation when you have cams/parts designed to redline at around 6k and up RPMs. You leave a LOT power on the table in such scenarios.

I think you should stay TPI... or just put a stealth ram intake on it.

If tuned properly a carb will NOT give up drivability. It iwll be more fickle when cold or in changing conditions, but if tuned properly and you're just driving around you shouldnt be able to tell a difference.

 

I wouldn't do anything to the engine. I would first do long tube headers and a nice exhaust with a good muffler and Y-pipe (I like dynomax and Mufflex...because that's what I have). Then, I would get a GOOD converter (like a 9.5" Vigilante with a 3000 stall rating). I would also do a shift kit in the trans along with a billet servo and an external cooler. When you are done with these things, you may realize 340HP isn't enough and you want 450. These mods will support that! I always try to convince people to do the engine last.

 

The TPI falls off really bad after 4500 rpms where as the RPM performer will support up to 5500 rpms really well. Your peak torque and possibly Hp is less because the TPI is designed (tuned) to maximize the air flow at a certain narrow rpm range. Most intake manifolds, like the Performer RPM are designed to cover a more broad range of operation which will make the peak numbers lower but it will provide more power over a wider rpm range which in the long run can make a car run faster like in a quarter mile.

 

dear friend i just completed a tpi to carb swap and here is what i have i have a 350 bored .40 {think they call this a 360} anyway i used a cast head from the 70's that are according to the numbers a 300 hp head summit racing cam 292 .488 lift with 114 lobe seperation a street dominator intake with 650 doublepumper 65000 volt hei distributor headman headers that still run single to dual except i have a 3 in pipe back to the rear axel of course i use platinum plugs with a 8 mm plug wire and i had to have a pete jackson gear drive over the double roller timing chain i like the noise lol now my car is a 5 speed and even tho i havent upgraded this yet i have put in a 3;73 ring and pinion to complement my posi unit and my friend let me tell you i ran this same block heads headers pipes tranny and rear with the tpi my fuel mileage has suffered but my car is awesome to play with now i love the feel of power when i put my foot down and drop a gear can't speak of exactly how much hp i gained but i can say it is night and day difference i would not change a thing i love my car now more than ever so enjoy what you have you will not be dissappointed except for fuel of course lol

 

a tpi camaro is one of the rarest things now and days. too many people hacked them out to put carbs on. but as far as the original question, possibilities are endless with either FI or carb, just make sure you do good combinations or neither will perform worth a crap

 

Thanks for all the input guys! I really ended up getting alot of suspension parts for the car to help it hook. A stall converter is a must of course. And thanks for the suggestion! I hope I will enjoy the car when I get home. But we will see how the car performs on the dyno when I get home. That will really tell if there was gains or not. Hopfully the UMI parts will help with the hooking and I think a Cam upgrade would do me good. Hopefully bump me into the 340 range. Maybe more. Any suggestions on a CAM head Combo with the intake? I am planning on running stock size DR'S and swap the 700r4 out down the road. The rear gear is a 3.42 just incase you need it!

 

imo i find that switching to carb opens up a huge performance potential, but just slapping on a carb wont get much gains, prob more of a decrease actually.

 

You needed a 670 cfm carb

 

Very true

 

3.73 are your best for the setup

 

A 3k stall for street

 

Hey, 3.42s are more then enough for the 700r4. And the 670 will be a good choice chris. Appreciate the feedback. But I guess the concensus is that the carb swap was a bad idea. All well it will do the job I suppose. I know it should respond better to mods like a cam and can be tuned without messing with the PCM. Also it breathes above 4500 rpm.. We will see Chris.

 

Here's what I was driving on a daily basis (engine finally gave up a piston after 100's of passes, shifting at 6800-7000RPM):

Stock 1990 L98 short block, AFR heads, RPM Airgap, 750 Mighty Demon, 240@.050 roller cam on a 109LSA, 4.10 gears in the stock rear, 700R4 with a 3600 converter, single 3" exhaust. Pretty consistent 12.0 with 11.89@115 in a 3000's DA being my best. Pump gas (92 octane) and pretty good MPG (14 combined driving).

Not a practical daily driver, but possible. A fun weekend car. As I said, decide what you want and then listen to the right voices to get you there.

 

Wow that sounds nice. That is about all I want. Sounds like fun. I appreciate the input bud! Was the AFR heads worth it?

 

I wouldn't necessarily say it was a bad idea, just the swap alone wont make a big difference.

As far as the stall converter goes, you need to pick your engine combo first. Just throwing a 3K in there might not be the best match for your combo. Once you have the heads and cam picked give the manufacture a call and have them recommend the right converter for you. You'll be happier in the long run. Hughes Converters & Coan are two good companies that can help with this

For good street performance and decent idle quality you will want a cam with a duration around 220* @ 0.050, a roller cam can provide a more aggressive ramp profile during the lift to get to the max lift more quickly providing a better cylinder volume fill.

Vortec heads are a good budget head upgrade but will not work with your current intake due to bolt pattern differences. I recommend a head with a intake runner volume around 190cc for your intake that you have. RHS Cylinder Heads have a good selection and Dart is also a good brand to look at as well. Aluminum is not a must but is preferred because it keeps the combustion chamber temps cooler which helps with detonation thus allowing you to run more timing and/or have more compression.

 

With the cost difference between good iron heads versus good aluminum heads, there is no reason to go iron unless you are required by a class racing situation. My AFR's are quite old and they have some port work done to them. The newer AFR 195's would walk away from my heads. So yes, they are worth it. My cam is a bit outdated too, there are probably 30hp hiding there. And, to be honest, the stall speed is a little low. A nice (streetable) 4400 stall would be about perfect. But I like to drag race, so every last 1/10th is important to me. If it is a weekend toy, I'd look more towards the 3000 stall range and some 3.73 gears.

 

^^^This

TPI itself contains a horsepower limit, in the form of its acoustic "tuning" (the "T" in Tuned Port Injection").

However, as the motor sits, it's pretty well optimized as a package, and just chaging out that one thing won't make much difference.

But what it will do, is remove that limit, that keeps other things from ALSO making a difference.

That said, I wouldn't put a carb on a FI car except as a last resort. I'd be looking at alternative FI intake systems. The Stealth Ram for example. While the Bird body is somewhat hostile to that particular choice, it works reasonably well in the Camaro.

Your 85 electronics are another major downfall of your existing setup. Getting a later ECM on there will make it ALOT easier to tune. Might want to consider changing to a speed/density setup.

Changing to carb isn't necessarily as cheeep as people seem to think. By the time you buy a carb, dist, FPR, and dozens of little detail things (TV cable setup, cooling system changes, etc.), you're up into the $600 range EASY; plus all the hack-job stuff that usually gets done (rubber fuel lines, wiring abominations, vacuum lines, etc.) leaves the car an unreliable trashed-out ball of excrement if you're not already REAL GOOD at that sort of thing. Not the best way to go. IMO, if the car came with EFI, best to keep it EFI and work WITH it, not just hack it all the way back into the 60s.

 

True but I have seen a set of good used iron heads sell for much less than a set of good used Al heads just because there is more demand for Al.

The true driving factor for your build is what do you want to do with your car and what kind of budget you have.

 

So ok here is the full story. I picked the car up for 700 dollars. The body is in fair condition as you can see by the pictures. It had a 350 in it already with the TPI setup. The car had a blown 700-R4 so I had it rebuilt. The wiring was torn up and the car would not run right. The TPI was butchered. So my buddy Chris (88rs the one doing the 440 swap) and I decided my best choice was to go pick up a dizzy and swap over to the Carb and Rpm performer intake I already had from a previous third gen I owned. So I did not spend more then 200 dollars on the swap total. I am not a fan of wiring or TPI. I am a HUGE fan of fuel injection but not TPI like I said. I feel it limited alot of potential plus it is a pain to deal with. So I feel I made the right choice. And as far as heads go. I am interested in the Patriot Freedom Series heads? Any reviews or opinions on them? Thanks guys I should of started posting well before I did the swap. But now that its done. What do you think my next plan of action should be?

 

To be honest it will be driven around 2 days a week. And bring it to the track maybe twice a month. I have a budget of around 1700$ any suggestions? It has a fairly fresh motor.

 

With only $1700, you will be limited. I would look at the EQ iron cylinder heads. Get them with just valves if you can and have the chambers cut down to 60cc. Combine this with a thinner head gasket, and you should be up around 10:1 (premium fuel). Then, get in touch with JRC Racing cams (Mike Jones). Tell him you want to peak at 6000RPM and he will design you a nice hydraulic flat tappet cam and spec out the springs and retainers for you. Then, you will still need all of your gaskets, a timing chain, push rods, rocker arms. This will eat up $1700 pretty quickly, but it should run good.

 

Is the 350 block a roller cam block or flat tappet cam block?

If it's a roller cam block I would not install a flat tappet cam into it even though the roller cam is about ~2.0-2.5x more expensive than the flat tappet cam. Pancherj has a good option for the heads.

 

I second the EQ heads! Good price and nice pieces. Mine, completely assembled for a very aggressive cam, with some minor work done to them, ran about $1200. They flow decently well, out of the box the 200cc heads flow data:


186/147
.300 lift
225/170
.400 lift
252/182
.500 lift
265/188
.600 lift
272/189
.700 lift

Box stock EQ 200cc heads compared to stock L98 heads:

 

It is a flat tappet, but I want to convert to a roller. $1700 is around my budget. I could go slightly higher perhaps $2000-2250 depending on if she will run strong. I really do not want Iron heads. I want Alum. Now my buddy chris a l98 vette engine with the Alum. heads and it does have a roller cam. He switched it to a non roller. Dont ask me why. But he might let it go to me for a decent price. It has a fresh fresh rebuild on it. I should know I was there when it was done. I am not tight on money at all I just cant justify spending much over 2000 dollars on my engine. It is an expensive hobby, I was giving you guys a ballpark number to be around. I can go slightly higher if it would me more quality and power.

 

I would like to go with a roller cam. But do you think it is necessary?

 

Heads are always the trick on any normally aspirated build.

 

I hope to see you on the track Billy lets get your camaro going.

 

At the power level we are talking about (350-400HP), a roller cam is definitely not a requirement. Save the money that a roller cam would cost and apply it to an even better set of aluminum heads. If you were willing to sping the motor to 6800RPM or more and you switched to a bigger carb and intake, then a roller cam would be a big difference.

 

Roller cams make huge differences when it comes to keeping a car streetable. A roller cam of the same size as a flat tappet will make way more power and have a wider rev range.

If you're willing to go to a solid flat tappet cam you can do nearly anything you want as far as power ranges go, though. That will really open doors but you better be careful about getting it broken in and adjusted properly.

These two cams have the same duration at .050, both are relatively modern (compare to the average edelbroke whatever brand flat tappet and it's night and day), and put on a 9.25:1 350.

XE268 - Flat tappet
http://www.compcams.com/Technical/Dy...68H-10_001.asp
342hp @5000RPM

XR276 - Roller
http://www.compcams.com/Technical/Dy...6HR-10_001.asp
373hp @ 5200 RPM

And the next step up from the xe268, the xe274, doesnt make as much power as the XR276, it's STILL less, and its at 5900RPMs instead of 5000 - 5200.

XE274
http://www.compcams.com/Technical/Dy...74H-10_001.asp
369hp @ 5900 RPM

 

Don't hamstring yourself with an off the shelf comp cam. Call Mike at JRC or another cam grinder. The cost difference is minimal.

 

Will do. As soon as I get stateside I will start to get this car together again. I would rather have a custom grind anyways. This way the car runs stronger then some generic cam would offer.

 

So is the power difference if you know how to choose a cam.

 

Isnt it funny how many dont start with the first like tires that put power to the ground.

 

It is true that if you know a lot about cams, you can spec one that works real good. The problem is the # of guys in that category are few. I have been at this a long time and I wouldn't claim to be a cam expert.

And yes, not enough guys think about getting the power to the ground

 

For starters I would like to thank you for your service, day in day out! Keep it together and get home.......

As far as the "switch to Carb from TPI" I am dead set against it, my friends and I were in the TPI when they first came out..... Learning what to do what they like and what was available to increase performance which was close to nothing back then! We got more serious in 1989. Heads mean a lot on an L98 same goes for a real camshaft and 1.6 rockers, proper tuning was difficult however we had performance resources from NJ and those chips were dead on. At this time we maximized the stock fully ported TPI since we now had the super ram,mini ram and the T-ram...... I personally hated the 700r4 even with a stall and all the "good **** to put in there" still junk so I began converting all of my cars to 5speeds and that is when they began to really run!
Stock L98 shortblock, AFR heads,230-560-110°,superram,30lb injectors,3.45 geared 9bolt,pulleys,Hooker Shorties custom 3" y-pipe had No problem running low 12s fuel mileage was the shock manual trans did the trick but you had to shift it soft or it would have a.**** fit!!!!!!! Then we got the t56 and it was on!!! BTW the fastest we were able to take the stock ported TPI was high 12 before it became a HUGE restriction but it made a **** ton of TQ...... AT that point we needed more HP and was willing to sacrifice TQ

 

Thanks for the advice and feedback EVERYONE!