Too much cam for TBI?

[hmatiak]

Just got a new tow pig. Planning on just doing a cam swap and intake and exhaust as the truck is very low miles. Already had this: http://www.summitracing.com/parts/CCA-K11-238-3/ cam for a carb 454 build i had planned, but now im thinking of putting in the new truck. I was told the lobe seperation was no good at 110, that it would be better at 112. Anyone with a similar setup? Truck is 1988 TBI 454.

 

[sweetk30]

i would do some reading at www.tbichips.com brian is the man. and he can do a chip for you also.

here is the 454 page http://www.tbichips.com/454ss.htm

 

[hmatiak]

Comp Cams "Camquest" program predicts 315 hp @ 3500 and 615 tq @ 1500. Thats with full length headers, 9:1 CR and stock peanut port heads. They also say "Excellent response, heavy towing in 454 with 4.10 gear."

Just some added info for anyone who might have questions about the cam choice.

 

[sweetk30]

Comp Cams "Camquest" program predicts 315 hp @ 3500 and 615 tq @ 1500. Thats with full length headers, 9:1 CR and stock peanut port heads. They also say "Excellent response, heavy towing in 454 with 4.10 gear."

Just some added info for anyone who might have questions about the cam choice.

i dont think you got 9.1 on a stock 88 full emmisions tbi 454 . prob around 7.5-8.1 is more like it. and to big a cam will make the computer run crapy.

 

[hmatiak]

i would do some reading at www.tbichips.com brian is the man. and he can do a chip for you also.

here is the 454 page http://www.tbichips.com/454ss.htm

Sent them an email a while back. Not sure if he replied himself, but the response i got was that the 110 LSA was not so good. They recommend a 112 LSA. Com Cams TBI replacement cam, the only one they spec, is a 110 LSA.

The site is useful, but looking for some input from home tuners or folks with a comparable setup.

 

[hmatiak]

i dont think you got 9.1 on a stock 88 full emmisions tbi 454 . prob around 7.5-8.1 is more like it. and to big a cam will make the computer run crapy.

Stock CR is 7.8:1. The heads are going to get pulled to install the new valve springs, guides, locks, etc. Was going to have them cleaned up, maybe taken down a little and put them back on with a thinner gasket. So i was hoping to end up around the 9:1 when finished. Its just a guess. HP falls off slightly when i drop the CR, but TQ stays about the same.

 

[rcamacho]

Milling the heads and intake to match may be well worth it to help bring up the CR.

 

[sweetk30]

like he said tho dont wast the money on tbi heads .

go get some 049 or 781 heads much much better in the end .

 

[hmatiak]

like he said tho dont wast the money on tbi heads .

go get some 049 or 781 heads much much better in the end .

The peanut ports are better than folks give them credit for. They will fit the bill better for this application too. Torque. Not planning on spinning it any higher than 4k. Correct me if im wrong, but the stockers will build more low end torque than the two oval port castings you mentioned.

The only thing i have doubt on the setup is if them prom will be able to be tuned to support the cam i already have.

 

[tRustyK5]

A gas engine "predicted" to make 615 ft/lbs at 1500 rpm and you believe it? A chipped Dmax doesn't make that sort of torque at that rpm...

I could probably believe 415 ft/lbs at 2000 rpm...but it'd be a stretch.

 

[hmatiak]

A gas engine "predicted" to make 615 ft/lbs at 1500 rpm and you believe it? A chipped Dmax doesn't make that sort of torque at that rpm...

I could probably believe 415 ft/lbs at 2000 rpm...but it'd be a stretch.

It makes nearly 400 from the factory with a stupid little cam. Again these are flywheel numbers on a desktop dyno type program. Id be happy with 500. Im not banking on those numbers. 500-550 doesnt seem unrealistic with cam, intake, full exhaust and all the emissions equipment removed.

 

[dave w]

Just got a new tow pig. Planning on just doing a cam swap and intake and exhaust as the truck is very low miles. Already had this: http://www.summitracing.com/parts/CCA-K11-238-3/ cam for a carb 454 build i had planned, but now im thinking of putting in the new truck. I was told the lobe seperation was no good at 110, that it would be better at 112. Anyone with a similar setup? Truck is 1988 TBI 454.

Why mess with a cam change? The cam listed above is fine. What I've done, and I think is a far superior upgrade to a 454 similar to the one listed above, is an upgrade to 454 Vortec port fuel injection system. A few hundred bucks, an ECM swap (including pins) and now your going to very happy!

dave w

 

[hmatiak]

Why mess with a cam change? The cam listed above is fine. What I've done, and I think is a far superior upgrade to a 454 similar to the one listed above, is an upgrade to 454 Vortec port fuel injection system. A few hundred bucks, an ECM swap (including pins) and now your going to very happy!

dave w

And how does this compare to a cam swap? Will the vortec stuff even bolt up to the 1995 and down heads?

The TBI system isnt terrible and it has plenty of potential to support this cam. Just need to know if the prom can be burnt to run it. Others with TBI and a similar cam?

If the TBI doesnt pan out, it will go on another BBC, and this one will get a Q-Jet.

 

[dave w]

And how does this compare to a cam swap? Will the vortec stuff even bolt up to the 1995 and down heads?

The cam swap will help performance, once the PROM is calibrated. The Vortec intake system will make more power with the same cam once the PROM is calibrated. Yes! the Vortec intake fits the BBC older large oval heads.

The TBI system isnt terrible and it has plenty of potential to support this cam. Just need to know if the prom can be burnt to run it. Others with TBI and a similar cam?

Yes, but I like the 8192 Baud Rate ECM better for PROM Burning / Emulating

http://www.thirdgen.org/techboard/tb...rting-tbi.html

If the TBI doesnt pan out, it will go on another BBC, and this one will get a Q-Jet.

OK

 

[hmatiak]

Looking for folks running larger cams in there TBI BBC's. The extra info is great and all, but im running what i got. Looking for input from folks with comparable setups, not which EFI system to run.

 

[dave w]

Looking for folks running larger cams in there TBI BBC's. The extra info is great and all, but im running what i got. Looking for input from folks with comparable setups, not which EFI system to run.

Program this ... then data log to dial in.

dave w

 

[hmatiak]

Program this ... then data log to dial in.

dave w

Not too sure what i'm looking at here?

 

[dave w]

Not too sure what i'm looking at here?

When the cam is changed in a TBI engine the PROM programming MUST also be changed! I posted the PROM programming for a 454 cam similar (but not exactly the same) to the cam profile in your original post. The picture below is a compare between the original PROM program and the modified PROM program. The ("+") / ("-") numbers are increased / decreased values of the new PROM programming compared to the old PROM programming. The ea$y way / low co$t way to change a 454 TBI cam is sell the 454 throttle body and install a quadrajet.
dave w

 

[hmatiak]

Well against popular demand, i will be running a carb. Simple and easily tuned for my new cam. This is a DD and tow rig so i think a good Q-Jet will do great. Going to run the stock in tank fuel pumps with a regulator and bypass at the carb. Should work great and the TBI system will get trimmed down and ran on a stock 454 in my trail rig in place of the underpowered 6.2 oil burner.