davenbocafl

lets make a bet and ill back it up, there a place here in boca raton called src performance and we'll name him a neutral party, he has a dyno

davenbocafl

your feelings are just hurt because holley out did your efi

davenbocafl

OK how can i prove it to you, remember theres no computer controlling the engine

rodj

You have a car with a stock CFI engine to swap a carb on to for testing?

davenbocafl

lets shack hands and start over, hi tom my name is david

davenbocafl

maybe we misunderstood each other, i said i took my stock 86 corvette and removed the complete fi including manifold and computer and replaced it with an edlebrock single plain intake and a 670 holley avenger carb and a summit 350/350hp cam and roller rockers and at minimum i picked up 100hp, 330hp was conservative and later went to the trick flow heads and a little larger hydralic cam and brought it to about 400hp and trick flow will back up the numbers

rodj

And the topic the OP posted that you responded to was

"I'm about to start my swap from cross-fire injection to quadrajet. I was just curious about what kind of #'s I can expect from a good 4 barrel quadrajet and edelbrock intake?"

This is the 1st you have mentioned yours being a TPI engine, not the CFI
"i chanced mine over to a 670 avenger holley, first phase was carb, edlebrock intake, roller rockers and accell distributer, it was about 330hp."

Crepitus

All right guys, at the risk of sounding like a little beech here; I see 3 guys that are very knowledgeable, have a lot in common and should enjoy friendship and a common intrest. There are 3 guys lookin at 3 sides of the same object and seeing different sides. If we were drinking beer in a shop all would be fine.
Typing short messages on the internet makes it very easy to miss understand each other
PLEASE dont make me quote Rodney King here!

cv67

Noones mentioned a crack pipe or baseball bat yet

davenbocafl

that is very true, if we were in a garage or basement drinking a beer we would be laughing in this debate.lol

Tom400CFI

You think? Which one of my cars did your "Holley out do"? My EFI'ed cars or my carb'ed ones?? lol

Lets see that dyno sheet. 125 gain from a carb/intake swap on a stock '84....

Tom400CFI

We sure did misunderstand. This thread is about an '84. And that is not what you said at all... the first time.

Here's what you actually said Remember that the following was supposed to be in the context of an '84;
In the spirit of "garage drinking", The OP can either:
*Carb it,
*Port and tune it
*Get the aforementioned REnegade and tune it.
...and end about at about the same point either way. Options 2 & 3 will retain EFI drivability and other advantages, while costing less too.

joshwiles

Wow lots of debate here. Alright here's my thinking, note that Im not dead set on carb. I was just thinking, I have no idea how to port my intake, and a renegade intake will cost me $500. With $500, I could get more carb related stuff and a cam possibly from local places. However, if I could get some decent performance from the CFI without spending over $1000, hit me with the plans and I'll make it happen. I'm un-informed on to what all you can do to a CFI engine and remain under stock computer control.

Crepitus

Tom, how much cam can I get to run in a cross fire? Can I tune the system to accept a cam in the 235@ .050 range? Or is the max something like the LPE219?

davenbocafl

tom, i got a feeling we're going to end up good friends, yes i got off the beaten path but i just loved debating with you

davenbocafl

what does cfi mean??(candy fuel injection) lol and then ill answer you. lol throw away the computer, it just cost you hp. even with a hyper chip,

rodj

Problem is not WHAT cam you can RUN ; but more a matter of if it would be any use,
The CFI intake ports are so restrictive that improving breathing with bigger heads / cam is of little benefit without a intake change
Check out the CFI intake port size here
http://www.digitalcorvettes.com/foru...25&postcount=2

Once you done a intake upgrade then the same parameters as any other engine apply.
Have to match cam / heads / intake relative to each other
Some reading
http://www.digitalcorvettes.com/foru...6&postcount=11

CROSSFIRE INJECTION
The twin throttle body injection used on 82 - 84 Vettes

Crepitus

Thanks Rod, the way I see it,
the first problem is the intake, port it or replace it. I have not seen flow numbers or port lengths on the Renegade or ported intake. Renigades and Smokey Rams are not cheep. (the TBs flow surprisingly well)
The cam is tiny. There is no chance of making any meaningfull power without replacing it.
More cam well require a tune. This is where the trouble starts. I have no idea how to tune the Xfire ECM. I have WinALDL running but am struggling with understanding the data. I doubt that I have the knowledge to replace the ECM with a after market one and write a tune from the ground up. An then there is the expence. EFI parts aint cheep.
Exhaust, Finally a simple solution, headers and good exhaust. This will probly lead to a slightly lean condition, easy fix with fuel psi.
Heads, for up to about 375 hp pocket ported 113s will do.
There is no reason the stock short block cant support 6500 rpm and 450 hp. My problem is I dont know how to get even close to that with the cross fire.

btw Grumpys forum is excellent I have been lurking there for a long time.
And thanks for your help

Crepitus

Josh; I aint trying to hijack your thread. I think our questions are pretty much the same.

Tom400CFI

With regard to cams and tuning there are no "set limits" on cams etc; any cam that you put in larger than stock will "require" tuning (note the quotes), and the more radical the cam the farther you stray from an optimal tune...obviously. So there are a couple way to approach this;
1. Learn to tune the ECM. For the CFI, that means (for most people) replacing the stock ECM w/the later TBI/truck unit that is more readily tunable.
2. Pre-plan an entire "package" that will work w/the stock ECM and built it
3. Build what ever you want, then do what ever it takes to "feed it what it wants".

"3" is the road that I blindly went down...and every thing worked out for me...and I learned a lot on the process. I got to the point where I just didn't care; "I'm going to put this part on, then deal w/the consiquences to make it work, later." -was my mind set. And that's what I did, part by part, mod by mod.


I can't speak to tuning the ECM because I never did it. I started w/a 305 CFI in a Trans Am (170hp stock), and ended with ~300hp out of a junk yard, 400 long block. First, using only Edelbrock "headers", and "Free mods" (Tstat, electric fan [which the '84 'Vette already has both those], advanced timing, etc) I went 14.50 at 95. It takes about 230hp to do that in a 3300 lb car, plus driver. Now that was on the STOCK ECM, chip, unported intake, and the 305 engine. Later I put in a 350, then a 400. When I did the (junkyard) 400, I put in a 224/234 cam, RR's, Ported the crap out of the intake, removed the swirl plates, radiused the lid transition, bored my TB's, installed UD pullies, and raised the towers.

To MAKE all this work, I upgrade the fuel pump, installed larger injectors adjusted the fuel pressure, added a Vacuum references FPR, and then fiddled w/it on the street and at the track to "feed it what it wanted" -no different than jetting a carb. The results were low 13's, easy 24mpg hwy, and a bone-stock like idle all on the stock ECM and chip/tune.

Here's what I learned. To make it work w/o changing the tune w/in the ECM you have to make more power (tq) in the same RPM range, or more importantly, you're engine after the mods, needs to have a tq curve that is the SAME SHAPE as before...only higher up, hopefully. The key to accomplishing that is to keep the cam's duration to the engine's displacement ratio, the same. Or close to the same. The stock cam is something like 202/208 -about 205* ave. 350/205=1.7. In my 400, I had a 224/234 cam -about 229* ave. 400/229=1.7. So the Tq curve in the 400 was about the same shape as the 350 (and original 305, in my case)...just HIGHER. That was convenient b/c that fuel CURVE, already existed in my ECM...all I had to do was give it more fuel (to match the added airflow), which I accomplished using larger injectors and more fuel pressure.

On a 350, I'd recommend going down the LSx road to more power; improve breathing using everything BUT cam duration. So better head, ported or improved intake, good dual exhaust, and more cam...but for lift only (or mostly). Then tune around that. But for starters, you can get to ~250 horse with nothing more than portiing and smart attention to detail, in your set up. All that will cost you is intake gaskets and labor. We're talking less than $100.00 here.

Joshwiles, For less than a grand, I'd port it, put some great exhaust on it, then dial it in.

For Crepitus, no way you'll get 450 horse through the stock intake, no matter how much you port it. For that, (if you want to "keep it CFI")you'll need a much larger Crossram intake. I don't know if the Renegade would swing 450, but I think an offy or SY1 might. And there is no way that you'll get 450 out of the stock ECM either, unless you go well over 400 cubes w/the appropriate cam, and/or are willing to sacrifice driveability in a big way. For that level of power (cam) you're really going to need to change the fuel curve.