Ok so as many of you know I'm not very pleased with the power numbers my car is putting out as of now. I still haven't figured out what's holding me back, but I still think it's in the chip tuning. I haven't had much time to mess with it because I bought a truck that needed an engine.
Anyway here's my question....all other parts the same will a carb make more power than an aftermarket TPI setup?? If so why?
I just read an article in the new CHP magazine about a 406 they built that put out over 500lbs of torque and 425hp. Their setup isn't totally similar to mine, but there are aspects of my engine that seem better and some that are worse. They used Vortec heads and I have AFR's, which I think are better than the Vortecs. (They should be for the money). They also used an RPM intake and single carb. The only other difference was in the cam. They had about 20* more duration in the intake side and 10* more in the exhaust side. My cam has higher lift and a larger LSA than theirs.
It just seems to me that I should be able to make much more than 264 hp at the wheels with my setup. Is carb just better than TPI for making power?? Someone explain this to me.

 

tpi is very restrictive without porting, If I were you I would just ditch the tpi and go with a performer rpm or victory jr intake with a holley 750.

 

I also totally agree that stock TPI system is restrictive without porting. Anyone could plainly see that if they have looked a stock base or runners. There is a lot of extra material in there that can be removed. But he already has upgraded to the Accel Super ram unit so that should help. If I had to guess I would also say it's the chip tuning since you've done so many upgrades. I mean you've already went form 22# to 24# injectors that can make a difference right there. Have you burnt a new chip for it?

 

There are lots of EFI engines that make more power than you, even with less engine underneath them. Hell, there's a 305 on the TPI board pushing 267 rwhp with a low buck combo.

In other words, your problem has nothing to do with EFI and everything to do with poor parts selection, assembly and/or tune. If i had to guess your engine probably has a tiny cam and too low compression coupled with a poor tune. It must have a few things like that in it's way to make so little power.

It may or may not go faster with a carb on it. If you don't know anything about carbs, then why bother leanring them now when you already have teh whole investment of EFI out of the way. If you can't get simple tables in the computer right, i doubt you're going to do much magic with a collection of springs, rods, jets, weights hangers, etc.

BTW, you have strange ideas about what makes combos "similar" 20' of intake duration is a HUGE difference, and 10' of exhaust is also very significant. Iron vs. AL heads will have very different needs/reactions to compression ratios as well. And a 406 vs. 383 also has the advantage of size. Still, 425hp out of a 406 isn't a huge number. Nicely done vortec headed 350s can easily match that number.

 

Now, what exactly do you mean by aftermarket TPI? Is it still the tuned-port injection system with mods done elsewhere, or is it an aftermarket MPFI, such as the miniram? If it's the former, you're going to be greatly restricted at higher rpm's, something carbs don't really have a problem with. But as far as which one's better right out of the box, well.. depends on what box you get it out of. I'm sure if you get the best carb, there will be a better efi, and I'm sure if you get the best efi you can find a better carb. But, as already said, if you've already invested money into efi, then stick with that.

 

I'm not trying to argue with you Ed... but try not to assume stuff.

Those two things have NOTHING to do with each other as far as what someone is able to do. I can tune a carb blindfolded (the carb, not me ), but I don't have a CLUE on how to tune an ECM.

Perhaps you missed the "500 ft-lbs." part? I don't know about you, but where I'm from we call that stump-pulling power.

You are right about the mis-matched combo thing as well as the duration numbers. Those can make or break a motor, especially a TPI.

 

My car has roughly 10.04:1 compression and the intake is the Super Ram with the Edelbrock baseplate. I want to pull the intake and maybe heads over the summer and port them.
The chip I currently have is from Ed Wright and has the 24# injector constant programmed into it.

As far as cam you're right about 20* being a big difference. I am also thinking about changing that in the summer to maybe the LPE 219 or maybe something slightly bigger.

With the exception of maybe the cam, what else could possibly be mismatched in my combo?

 

What cam specs are you currently running?
The LPE219 would be an exellent choice since it was made for the Super Ram.

It takes high RPM to achieve high HP numbers. Since the Super Ram allows for 6500 RPM, you should be seeing higher HP figures than with a LTR set-up. You'll lose a little low-mid range torque with the Superram, but with a 383, it shouldn't be too noticeable.

 

My cam is 210/220 .50/.510 112 LSA

The springs on my AFR heads suck though......I was getting valve float at like 5200 rpm's.

 

5200 RPM?!?! That ain't right. Replace those springs.

Your cams duration would work OK with LTRs, but the intake duration is too low for a 6500 rpm Superram.

The LPE219 cam has proven to be a great cam. I'd use it with some suitable springs.

 

No sweat, you just missed my point. You obviously know your way around a carb and mechanical dizzy, so why learn the EFI stuff if you're happy. In his case though, if he doesn't know about either, why junk the EFI stuff just to learn something that really is more complicated. I know carbs seem simple once you understand them, but to a beginner concepts like altering pump shot duration or power valves, etc are harder to understand than a table that says MAP vs. RPM.

 

Thats a TINY cam for a 383, probably idles better than a stocker. I'm going to be running a bigger cam in my stock headed 305.

Still though, you should be able to make more power than that. What kind of compression are you running? And are you guessing, or do you have deck height, piston relief volume, and compressed gasket thickness factored in right. Granted thats a small cam, but i'd still be shooting for over 10:1 ACTUAL compression ratio in an aluminum headed performance motor. If you *think* you have less than that, you probably have a lot less, which is only going to suck your performance away.

And beyond that, a low compression small cammed motor is going to tend to be sensitive to the tune, varying pretty widely because of how hard it is to optimize cylinder pressure when you don't have any.

 

Yeah I think I went way too conservative with the cam...I was worried about passing emissions.

The compression is a guess, but a good one as far as I'm concerned. It should be roughly 10.04:1