Blazer79

Found some interesting conspiracy theory about the Crossfire. Thought I'd share with you:

http://www.smokinvette.com/corvettef...ead.php?t=4359

coolram62

iTrader: (2)

That is very good reading and hits the point exactly. The Vette's L83 also didn't have to deal with the restrictive exhaust from the LG4. I've ported the base on my LU5 and replaced the manifolds with ones from a L69 (along with the y-pipe and 4 bolt cat). This really made a world of difference in driveability and seat of the pants acceleration (haven't had her on the track yet). The L69 and LU5's cam specs are very close and the LU5's CR is the same also. It would have been interesting if the LU5 had received the L69's exhaust but then the L69 was a big selling point for simplicity (but really more complicated with the CC as the Vette Forum stated). The one mod I haven't done is to upgrade the ECM but that will hopefully come later.

Drew

iTrader: (58)

That post sounds like a lot of wishful thinking. I can't see GM shooting themselves in the foot with the BRAND NEW flagship of the brand, just to make the system that might come out a few years later look better.

It's much more plausible that in the course of adapting the first generation cross ram intake to a modern choked down V8, compromises had to be made to make the engine work where the vast majority of Corvette owners would actually be using the car. A lack of top end performance wouldn't matter as much to the average Corvette owner as bogging and sputtering at every stop light because the fuel is falling out of suspension and puddling in the intake. We're talking about an intake intended for a 7,000rpm late 60's race car, and adapting it to a smog equipped, daily driven, Corvette. Compromises had to be made which killed the performance potential. Be glad that CFI cars run at all.

coolram62

iTrader: (2)

Drew it wouldn't be the first time an auto manufacture shot themselves in the foot. True at the time they were trying to make a compromise between ever tightening EPA/CAFE standards with some resembelance of performance. Have you ever actually taken a CFI intake apart? The base is so crude compared to what a finished intake should be (even for mass production). This to me ,yes opinion, is an indicator that this was intended as a stopgap while something else was in development. The L69 being released also indicates GM knew the CFI equipped motors were handicapped. It amazes me that the C4's L83 had CFI instead of the L69's carb setup. Don't get me wrong I love the CFI setup and have worked to improve the setup on my '83. It's just there are so many documented problems from the '82-'84 period on F & Y Bodies that led to most CFI F Bodies being converted (Vettes for their very stature/nature faired immensly better). The 700R4 and TPI had it's share of issues when first introduced.

DizzTransAm

I've owned my crossfire T/A since march and have put 4k miles on it... and I love it I've yet to have sort of problem with the CFI or any of the driveability problems I've read about it. I think it was really blown out of proportion like the Northstar headgasket issue or Fieros catching fire.
Seem to get decent mileage its a blast off the line and with the cowl induction opened all the time its kinda neat hearing the "whistling" from the injectors. Can't wait to get my Renegade intake next month.

KITT1983

iTrader: (3)

let me know how your renegade turns out

Drew

iTrader: (58)

Uh, HELL NO! I was pretty excited to see a CFI Z28 sitting on a used car lot. I mean it was a Z28! and had that cool fuel injection with a functional hood! This was going to be fun! Then I pressed the gas at the first stop sign and my smile turned into a frown. I tried one or two more stop signs, turned around and took the car back to the lot. My LG4 would have run away from that Z28 like it was chained to a tree. I've driven a couple since and they were all lethargic. No reason to take one apart, because like I read on here years ago, if I saw someone dumping one in my yard, I've pay them $20 to dump it somewhere else.

So it's more plausible that GM would develop a 4BBL, get it to pass emissions, and put it in the Camaro, instead of just fixing the intentional flaws that link suggests?

The suggestion of that article linked earlier is that GM caused the problems on purpose to make TPI look better. But that doesn't make much sense. GM had a huge investment in the new Fbody and the C4 Corvette, why would they intentionally create problems in their hot new product? It raises more questions than it tries to answer. It was a gimmick that didn't perform well. There's no reason to try to excuse the problems.

coolram62

iTrader: (2)

How old was the CFI Z28 you test drove? In stock form they perform great off the line and up to 4K RPM. After the that the engine justs run out of breath due to the intake runner design and restrictive exhaust. Also I believe 2.73 ,or 2.77, was the standard rear ratio with 3.23(G92) being the only option (L69 benefitted from 3.73 and 5 speed).

As stated the L69 option does seem to be more of a stop gap once the CFI flaws ,and reliability/maintanance issues, really became apparent. The early LT1 Optispark is another example of engineers not doing their homework and enough testing.

I'm not trying to excuse the problems the CFI motors came with in stock form. I'm just saying it was a good idea for the time but suffered from poor execution. With a few mods (lower manifold port intake,better exhaust for example) they can really perform. It's really no different than what one would do to a TPI motor.

KITT1983

iTrader: (3)

got any links to a good cfi performance exhaust

coolram62

iTrader: (2)

KITT what I did was replace the stock exhaust manifolds/y-pipe/cat (again shared with the LG4) for a setup from a L69. You can use a set from a L98 but the driver's side AIR pipe has to be reused from your stock manifold as the L98 is reversed. Certain LB9 mainfolds will work also but I don't have the part/casting numbers handy (have to be careful as some were shared with the LO3). A highflow 4 bolt cat and a good catback system will finish it off. make sure you order the catback for the L69 and not the LU5 (I prefer Dynomax for good flow and sound P/N 17494 http://www.summitracing.com/parts/WLK-17494/ This is a different part number so best to research it ), You ould go with headers but you lose the stock appearance and to me headers at this performance level are more a hassle.

Six_Shooter

iTrader: (2)

I know I'm one of the few that has swapped the CFI onto a vehicle that it was never intended to be on. That vehicle is my Grandfather's 1971 Chev pick up that is VERY modified, slammed, chopped, custom frame, custom body mods, etc, etc. It originally had a 283 in it, with a carb, then a Vortec 350 was installed, that never ran right, turns out we were running the wrong plugs in it all along. DOH! I did modify a CFI lower to match the Vortec heads, the only one that I know of. lol Currently there is an earlier 305 installed due to discovering a crack in the starter pad in the block of the Vortec engine. I got two lowers with the system when I bought it. One was a brand new, never been installed unit.

I'm also running a 4L60E behind the 305, and running the show from a 16197427 PCM, that was pirated from a 1994/5 TBI truck. It runs well, the bottom end torque is quite impressive and lights up the 19x32 Mickeys pretty easily.

I have a slight issue with high idle currently, but when I get some time to look at it, I should be able to sort it out pretty quickly.

okfoz

All I know is I took an 82 or 83 Camaro with the CFI in it for a test drive... I was absolutely shocked how quick it was. I am not sure what was done to it to make it run like it did, but I am certain it was a low to mid 14 second car....

They wanted $1000 for it, but the trans needed rebuilt, it would not shift unless you floored the car...

John

John

Slater126

iTrader: (1)

Yup, it was called the L69 and it appeared two years later. As to the why, about the only thing I can think of is that GM put a lot of stock in fuel injection, partly to save fuel and partly as a marketing tool. I doubt the restrictions you cite were really understood when the design first hit the drawing board and by the time it gets going, well, there's always going to be a certain amount of institutional lying to oneself, if you know what I mean. The end product was disappointing so they changed it. Simple as that.

83 Crossfire TA

iTrader: (2)

Nice, i was going to swap one onto a '92 K1500 blazer but had to sell the truck, long story. The fact is that it's a killer setup for that kind of application.

Like I already said, it's got better low end then a comparable TPI setup, and will kill a similar car from a stoplight as long as the race isn't long enough for the top end to become an issue. (I actually currently own an L98, LB9 and LT1 car, so it's not like I'm comparing it to someone else's car that I don't know the condition of or that I drove once, I drove the LT1 to work most of last week and the LB9 to the gym on monday and wed and out for dinner on friday...)

Honestly, for a street car with a reasonable sized traditional SBC I don't know that I could name a better setup, especially a factory setup. A TPI looks cooler, but doesn't do better in any category, it doesn't have the low end, neither has the top end, the CFI will get better mileage...

A CFI 305 or 350 with some minor mods, small tube headers, nice exahuast, mild stockish engine setup with fairly high compression, decent OD transmission and tall gears will run low 13's get mid 30mpg without any dramatic work. Good luck doing that with a TPI or carb.

As far as the conspiracy, well GM is well known for doing that kind of thing, crippling engine packages to prevent lesser cars from performing as well as what was supposed to be their performance leader (Corvette), the vettes often got the same engines as other cars with better exhaust (and in the case of the TPI better, lighter aluminum heads) to make them faster with no other differences, heck, even with the CFI they had the same setup available in the f-body but only as a 305. The GN, GNX and TTA were disasters as far as GM's official party line goes, but notice that the good cars weren't even tagged as officially coming from the major GM divisions (the TTA and GNX did not have pontiac and buick manufacturer's tags)

chazman

iTrader: (4)

Consider a CFI kinda like an L69 but with a corked up exhaust, more tempermental induction and weaker gears. They will run pretty crappy if they are neglected for years or decades.

Mine ran HORRIBLY when I bought it. Ran rough, backfired, sputtered, and it was S-L-O-W. But...I got a wild hair to buy a CFI and fiddle with it. And fiddle with it I did. It runs exponentially better now, certainly faster than an LG4, but honestly, not as smooth as my TPI. Maybe there's a vacuum leak I've missed.

Anyhoo, pop the hood of a nicely detailed Crossfire at a show, and people check it out like it was a Ferrari Lusso.

scottmoyer

I've edited the thread to remove the arguments and most of the posts that didn't pertain to the subject.

A comment was made that moderation of the site was better years ago. Let me state that I do not spend my entire weekend following every thread. I have better things to do. As adults, for the most part, I expect that you all can conduct yourselves accordingly and not fight with each other. Comments and opinions get voiced and others disagree. It happens. Play nice or the thread gets locked.

kmcn47

and not just this thread, all threads in every section

nelson84

I like the crossfire and it runs better than my TPI. I installed a renegade intake manifold. It pulls well past 5000 rpm, I shift at around 5300 - 5500 rpm.

Coyote850

iTrader: (1)

It seems hit or miss man. My Z-28 runs great, but others run terrible............That looks awesome BTW.

KITT1983

iTrader: (3)

My CFI ran great when I bought it. Then the CFI curse began show itself this april and then I fixed it and now it is running better after rebalancing the tbis, new EGR, nad new IACs. I still need to put a 180 degree thermostat in as the 160 thermostat wont let the car run in closed loop. I plan on getting the renegade when it becomes available for sale again.

nelson how does the new intake run?

chazman

iTrader: (4)

Tell us more about your impressions on the Renegade. Was it worth the money? What was your seat of the pants "feel" compared to the stock intake?

nelson84

Others run terrible because they need a tune up or have vacuum leaks, or both. Just bump the timing up a little and raise the fuel pressure up to 15 psi and they are much more responsive. The thottle bodies might need adjusting or are wore out. When these cars are this old they need some updating. A renegade or porting the intake manifold helps lots. My crossfire runs better than my TPI but my TPI is stock and old.

Coyote850

iTrader: (1)

I'll definitely remember that if mine ever acts up.

nelson84

The renegade pulls good from a stop the tires squeel and when it hits second gear the wheels spin again and at about 3200 rpm it really starts to pull. My best time is 13.98 in the 1/4 mile. The best direct replacement intake for the crossfire.

82tarecaro

iTrader: (4)

I have the Renegade sitting in my basement. I was going to put it on my 305, but now I am considering building up a mild 383 for it. It seems a waste to put that intake on a small displacement engine, as it is a nice piece, with large intake ports. The guys from DCS really did an exceptional job with it. I really hope they keep making parts for the Crossfires because they are about the only game in town.

TTOP350

iTrader: (8)

that intake would look nifty with a adapter plate for a TPI T-body on it! The runner ports look a tad small for me tho..

Tom 400 CFI

Where are the large exhaust ports? I only see intake runners in the pics...

83 Crossfire TA

iTrader: (2)

lol... I was just going to let that one go...

Six_Shooter

iTrader: (2)

Do you have to transfer over the little fan blades from the stock intake to the Renegade intake?
I haven't tried it myself, but I keep hearing stories of people that have removed those blades and the car ran poorly afterwards.
My Grandfather and a friend also tried using a Crossfire lower with a custom machined top at one point for a 4bbl carb, that never seemed to run right and wondered if it was the lake of fan blades on that set-up as well.

Tom 400 CFI

I ran mine w/o them and had no meaningful issues. This was with bored TB's, and fully ported intake.

The only issue was when starting the car cold, on a cold morning. By "cold" I'm talking below 20*F. For the first 30-60 seconds, I'd have to let it warm up to avoid slightly rough running when pulling away. AFTER that 30-60 seconds, it ran perfectly. This, also with 1 160 stat, and a manually opened cowl valve, with the under-hood intake blocked off. IOW, COLD air induction only.

I have to think that if my car ran fine under those circumstances, the "fan" is not necessary unless you live in Alaska or something fairly extreme.

82tarecaro

iTrader: (4)

You are right Tom - my mistake LOL!
Tom - I would really like to ask you some questions about building a 383 with Crossfire that makes at least 350-400 HP without computer mods. I know you have a strong running 400 and you did it with bigger injectors and added fuel pressure. What is the most HP possible from this combo with stock computer? I am hoping for a decent set of heads, possibly a roller cam, and free flowing exhaust.

82tarecaro

iTrader: (4)

It is hard to tell from the pics, but the intake ports are quite large, and mate up with a Felpro 1205 intake gasket.

KITT1983

iTrader: (3)

what fan blades ?

Dens71TA

iTrader: (5)

The swirl plates that are underneath the throttle bodies. They are suppose to help fuel atomization.

83 Crossfire TA

iTrader: (2)

I don't think they are an issues for performance, but they are for part throttle driveabliliity and MPG. I've always left them, but cut the sides open and have never had an issue with them

you know, thinking about this my best time with my '83 Crossfire 305 with a stock long block is over a second and a half (maybe 2, I have to find some timeslips) better than the best my 87 TPI 305 (LB9) car, and MPG isn't even close in the LB9...

82tarecaro

iTrader: (4)

What were some of your mods, and what is your best et?

KITT1983

iTrader: (3)

do you have a photo of these swirl plates ?

nelson84

The swirl plates are not used with the renegade and I think it runs as good if not better than with the swirl plates.

83 Crossfire TA

iTrader: (2)

Low, low 13's (need to find timeslips again), 13.8 the last time it went to the track but it had 2 wiped out cam lobes.

There are pictures and details way back when on this message board (I had that car from '92-?), but short version:
- bored TB's
- 1" tb spacers (cut out of hardwood)
- 1/4" injector pod spacers
- modified fuel plumbing/16psi fp
- K&N filters
- home made cold air intake
- custom tuning
- 1.6rr's
- headman 1-5/8" primary headers
- 2.5" primaries, dual highflow cats, flowmaster y, 3" dual (and later single tailpipe) with no muffler
- _a lot_ of suspension work (was pretty serious about autox and also drag raced every weekend back then)
- tons of other drivetrain tweaks/tuning

82tarecaro

iTrader: (4)

What kind of custom tuning did you do? Did you swap to a later model computer?

83 Crossfire TA

iTrader: (2)

it was actually a bunch of custom proms in the stock ECM... later on when I got into ECM tuning I was never able to figure out what was done or recreate the rom (I think I have a copy of what I read off of it, but it didn't seem to work burned to another prom). If I was going to do it today I'd probably use a later truck ECM (I have a few '7747, '299, and 730/749 sitting around), EBL or something similar, maybe even try a MS...

Tom 400 CFI

I never observed anything that supports what you are saying. My part throttle driveability was fantastic and I got 24+MPG with my 400 which was as good as my stock 305 with swirl plates intact


This, I did observe. At the same time my car was stock+ exhaust I had an 86 TPI that was a second slower and got worse gas mileage.

82tarecaro

iTrader: (4)

Tom - what did you to to get the 400 to run properly? I am hoping to do something similar with a 383.

Tom 400 CFI

I just typed a huge reply and hit "Submit" only to find out that thirdgen had logged me out. Sweet.

Here is the short version:

I believe that my combo worked because the cam, combined with the displacement, resulted in a new tq curve SHAPE that was similar to the shape of the original engine. This means that simply adding more fuel (larger injectors) did most of the required "tuning". The 400 had a FULLY ported intake, 224/234 cam, bored TB's Edelbrock TES "headers" and SLP cat back. Tuning ultimately consisted of 90pph injectors, base timing adjustments, the addition of a vacuum reference FPR, and dialing in the fuel pressure. MY results were:
13.25@105 in the 1/4
24+ mpg hwy
stock-like idle
Wicked throttle response and torque (I could 1.8 60' leaving at 1200 RPM).
5000 RPM shift point.

It was fun.

82tarecaro

iTrader: (4)

So, for a 383, if I pick the right cam, the stock computer should work with larger injectors and the vacuum referenced fuel pressure regulator? What type of heads were you running? Would a free flowing set of heads cause issues because the engine flows better and needs more fuel?

chazman

iTrader: (4)

I love threads like this, because it gets me excited about owning a CFI again.

I've done the exhaust and most of the maintenance items that a CFI requires, and it sure runs alot better than what I started with. It still doesn't seem as smooth as my TPI though, so I'm wondering what I've missed. I haven't balanced the TB's yet, but it doesn't really appear to me that they are out of balance, maybe there's a sneaky vacuum leak somewhere I've missed. Any ideas?

Anyway, on some of the Corvette CFI boards I visit, it seems that more agressive computer tuning, (in the form of an aftermarket chip), gives almost guaranteed results, usually about .3 second in the quarter mile. What do some of you more knowledgeable folks think about that. Is it possible that these early ECMs had VERY conservative tuning and have greater potential for some performance benefits?

Also, I feel as if the 2.93 gears are really holding my Crossfire back. I'm thinking a 3.73 would be too much considering the intake's RPM limits. What do we think about a 3.23 vs 3.42?

83 Crossfire TA

iTrader: (2)

I honestly don't remember what the thing was like with the stock plates... I cut the sides out of mine fairly early on and ran them that way most of the time I owned the car.

82tarecaro

iTrader: (4)

I didn't even know that custom chips were made for CFI. Over at the Croosfire Injection Vault, custom tuning always involves installing Ham Boards, swapping over to later model computers, and datalogging.

Tom 400 CFI

Probably, but it boils down to feeding it what it wants. The stock ECM/chip has a fuel "Curve" already in it. If you build an engine that has a similarly shaped curve, only higher, then yes, simply adding fuel will work. What do you have to do to you combo to make the fuel curve the same shape as stock?

I ran stock 400 heads on my 400; the whole thing was based on a junk-yard dog, 400 long block. What would heads do? I personally feel that better heads would make the task easier, as you could run a smaller cam to meet the same goals than with stock heads. I haven't tried it though, so I'm guessing.



Have you addressed all the basic tune up items? Is the engine mechanically sound? Do you have good fuel pressure? Timing set correctly? I agree that TB balancing isn't as critical as some make it out to be; if they LOOK like they're damn-near identically set, they're good enough. In fact, experimenting with my TB's synching didn't really affect the idle smoothness much...until after they were quite visibly out of whack. I'd confirm ALL of the basics, then check for vacuum leaks (likely the problem). It should idle every bit as smooth as the TPI.




AFAIK, DCS is the only company offering a chip for CFI, at this point, but at various times, Hypertech and ADS were. I feel that all the settings (both mechanical and software) are conservative on a CFI engine, but the timing is the most, so. I have yet to see or hear of a "chip" for CFI actually improving performance, and in fact I know three different people who tried (three differen brands) that all slowed their cars down (at the track and on a dyno). ALL the chip can do is change the timing and fuel. You can do that with base timing and FP and since the CFI has a pretty flat torque curve, it works prety good. Good enough. I wouldn't waste my time with an aftermarket chip. I feel that if you want to improve the tune that's in the chip, start burning chips for YOUR car, rather than buying "boxed tunes".





I agree that you need more gear. I had 3.23's, and 3.45's behind my CFI and I liked the 3.45's the best. For my combo, the 3.73's probably would have been low, but the 400 had plenty of low RPM tq.

chazman

iTrader: (4)

Pretty much. I advanced intial timing by about 4*. I do admit to not checking fuel pressure. I've never done that before, seems fairly straight forward to do. Anything tricky about doing it on a CFI? Idled much better after I tightened up the top plate and TB bolts and cleaned out those gunked up IACs.

That slight roughness BTW, is not so much at idle, you kind of feel some coarseness when you rev the motor. It's not bad, but I can definitely feel the difference between it and my TPI which revs as smooth as a Swiss watch.