Clearly, something is wrong with my setup.

I think I have about 400 hp, when I should have over 500.

Here are a few possibilities I've been told that could be the issue:

1. I need it tuned (havent had it tuned after installing the p600 12psi supercharger)
2. bigger fuel injectors (I currently have 24lb fuel injectors)
3. differnet intake (I have stock tpi intake...unported)
4. the bypass valve may not be set right, and then I may not be seeing all the boost I could be.

What are all of your thoughts on these?

Here is why I think I am slow:
I can put a few car lengths at most on my buddy's 331 stroked cobra who has lots of suspension mods and a 5 speed and was dynoed at 330 rwhp, but he got more done to it now so it would probably be more like 340 rwhp.

I ran against a '03 Z06 and he got me pretty good. This was on the freeway.

On the street, I ran a new LS1 Trans Am with a heads/cam package .... the guy put me on a leash and took me for a walk all the way down the street. He claimed 11.50's.

Any ideas???

 

numbers 1,2, and 3

My ZZ4 dyno'd 267rwhp w/ the all the crap I got. That was w/ the stock intake. You loose so much to the TPI

 

I have heard both sides of the tpi with boost deal. One thing I keep hearing is that since there is boost going in, then the tpi is no longer a restriction. Any thoughts on that as well?

 

have u had your car dyno`d????
if not go get dyno`d.alot of things could cause a loss of power.like fuel,spark,exhaust etc.u need to find out how much power your making and go from there(look at the curve).what gears u running.


dave

 

the best so far I have gone on a g-tech was 13.0 @ 115.6 mph or something like that with a 200 lb friend in the car. The other night, I tried and got 13.1 @ 113.8 ... I took off the filter and ran a 13.3 @ 112.6 ... these runs were with my friend in the car too. I am running 3.73 gears by the way.

 

#1 and #3 are huge red flags for where to start.

A restriction is always a restriction, even under boost it will cost you.

 

If I were to ever, ever change the intake it would probably have to be something like straight to a carb setup. I have a carb hat for it. Based upon what freebird said, it looked like he was getting about 300hp at the crank. The zz4 with a carb dynoed at 355! Is there a lot of power to be seen just by changing to carb then?

 

Check this out. Theres a part in there comparing a ZZ4 with a TPI to a ZZ4 with a carb. Have you put a gauge on it to actually check your boost?

 

actually, no I havent put on a gauge yet. Shortly though, I will. I was really really hoping for mid/hi 11's since ATI boasts they can get a stock tpi l98 into the 12's. I was a consistant low 13 car before the blower.

 

Remember this phrase"BELT SLIPPAGE". I've had so many problems with my D-1SC with belt slippage. I got dyno'd at 278uncorrected hp the first 2 pulls. Tightened the belt and played with the air/fuel and put down 343 uncorrected hp. Get a boost gauge first, make sure you building the correct boost, tune the car at a dyno shop, and come back to us. Your ZZ4 started with a lot more hp than me and with my procharger at sea level I guarantee I'll hit 12's. GL

 

If those G-Tech numbers correct then you are looking at nearly 400 hp at the wheels (assuming 3700 pounds). Thats around 500 hp at the crank and enough to go low 12's with traction. By the low et, I'd say you have a big traction problem that needs to be addressed. Get it to the track or dyno so we have some real numbers... we are little more than guessing with g-tech numbers.

Is that a 12 psi procharger kit with an intercooler? Perhaps that number is the pre intercooler boost. On the mustang application I played with, the intercooler dropped 3 PSI from the rated boost of the kit (14 psi). The kits were known as 14/11 pound kits. Anyway if you have about 9 pounds of boost considering a little bit of heat losses and some parasitic losses thats about a 50% gain in power. If thats correct, your looking at about 330 hp at the crank w/o the supercharger. From those numbers I think you are in the ball park but its all based on a G-Tech, not real numbers....

You asked about the TPI being a restriction under boost. TPI is a restriction about the 4500 ish rpm point and power numbers up there will be lower than with a shorter runner setup because of it. Many people dont think it is a restriction because when they bolt on a centrifical supercharger setup they pick up useable RPM range. This is because of the boost curve of a centrifical. Its adding boost faster than the motors power is dropping off so it expands the RPM range. Swap to a shorter runner intake and the power gains in the same RPM range will be dramatic... but you might have to pully it differently to see the same boost since you are removing a major restriction. A shorter runner intake might also help solve some of your traction problem since you will be making lots more low end torque. The new stealth ram looks pretty sweet... I'm running a victor JR converted to multi-point which as I understand is available off the shelf now. In reality though all you really nead might be a set of drag radials.

As said before, to do more than just guessing we need to know some real numbers dyno or track (preferably both) and we need to know what you are seeing on both a boost gauge and fuel pressure gauge.

 

One question for you? Do you have a boost referenced regulator on the car? Without one you will only be getting the normal fuel pressure of a n/a engine. With boost the best rule of thumb is 1 psi of fuel pressure for every 1 psi of boost. Meaning that if you set the base FP to 43 psi and are indeed running 11 pounds you should be seeing 54 psi on a fuel pressure gauge.

Without it you risk detonation and a seriously lean condition being that max boost isn't until the higher rpms. Just a thought for you. The other contributing factor is the 10.5 to 1 static compression, it may be knocking retarding the timing hence not making any usable power up top where the blower likes to spin.........


Pete

 

To be honest with you, I'm not quite sure. But I do feel as if it is not nearly fast enough on the freeway.

 

If you aren't sure whether you have one or not you probably do not. There are four ways of assuring adequate fueling.

1. Boost reference regulator(when the vaccum disappears from the regulator it will increase the FP when boost comes on).

2. Burning a chip to add the fuel through the tables(takes some dyno time and continuous adjusting/reburning).

3. On most FI cars the maf is a draw through design(I don't know if you have a maf or sd car), being that the maf sees a certain amount of air drawing through it(measured in grams per second) it measures the air uncompressed then through the blower.

So the air that the ecm calibrated the fuel for originally may not be enough. By going through a blow through the ecm will see the air as it is going into the engine. However the limiting factor is that the ecm can only read 255 grams per second in which case once the maf is maxed out it will no longer make a correction to the fuel.

4. Using an FMU(pretty much the same as a boost referenced regulator. Some companies include them in there supercharger kits.

If you're sure it is running correctly dump in some 100 octane and put it on a dyno. They will be able to give you the a/f ratio to help you tune. Different engines like different parameters but 12 to 1 afr is a good place to start then you can lean it out to make achieve the best power.

HTH,

Pete

 

You may not only need bigger injectors but what about the fuel pump? is it stock? Fuel filter? With boost you need a good fuel pump that is capable of providing the volume the motor requires.

Just my$.02

Prasad

 

Heh… funny… You’re all kidding, right?

First, quit worrying about the TPI intake. The runners/base are its biggest restriction and they flow about 200cfm/runner. That’s enough to feed just over 600hp with 12psi boost (assuming 70% compressor efficiency and 70% intercooler efficiency, both very reasonable #’s). If you’re not making more then that then that isn’t your problem.

BTW, there is no reason for and engine using a stock TPI intake to stop pulling at 4500rpm, there is a damned good reason that you should shift around there, the peak caused by the harmonic tuning of the long runners gives you the best area under the curve if you shift around there, unless the TPI is on a 305 that is built to pull into the mid to high 5K range, then you’d be better off shifting up there (3rd harmonic tuning point).

Second, are you running the aluminum heads that came with the ZZ engine? Let me give you a hint, the L98 iron, L98 ‘vette/ZZx, LB9 and LOx heads are the biggest crap that GM has made. Swap them for a set of STOCK later or earlier heads, even LG4/LU5/L69 305 heads, and you’ll make more power. The heads are the reason that L98’s fall on their face in the high 4krpm range, they only have enough airflow to feed a 350 to about 4700 or so before VE has to drop off because of lack of head flow.

So what’s wrong? Well, I could make some guesses…

What are you doing for fuel enrichment? You’ll be lucky to get 400hp out of 24lb/hr injectors. If you’re using an FMU what fuel pressure are you seeing? Are you actually seeing 12PSI at the intake or at the compressor outlet? What’s your compression? Are you running high enough octane gas/reasonable timing so the ECM isn’t pulling out spark? Once it starts doing that it pulls it out in large chunks that will kill power.

 

Let me first say that the ZZ4 heads CAN make good power. What type of injector , SVO? You need to do some data logging on the dyno. That will tell the story. BTW, I'm 10.9:1 C/R. No detonation here. Tons of dyno time!!!

 

Verify tune of engine. Start with a compression test.

I have a P600 in a boat with a 383 and at 6 PSI boost (4500 RPM) and I am running maximum duty cycle at the injectors with 24#/hr.

U need bigger injectors (I do to!) Next is the bigger fuel pump.

You have a good (and cheap) source to verify tune with the G-tech. Dyno time is for "fine tuning" not troubleshooting.

 

You have 83 ci more than 84IROCZZ4. You do need more injector. I'm not so sure he does. That is a good bit of money you are telling him to spend when he has no data logging time on the dyno. Find out what the problem is... then fix the problem. The money spent on the dyno will be well worth it.

 

The more I think about it the more i'd have to agree the problem is fuel. ZZ4= more ponies to start than me, blower on top of that = even more. I have 30#/hr injectors and when I tune my A/F ratio at the dyno it is perfect with respect to the 30#/hr injectors. You prob need more fuel. Keep us posted.

 

I'm not kidding about what I said about TPI being a restriction.

Runner length is the #1 factor in where your engines torque curve starts and stops.

In your example you used a very well tuned maximum effort including aftermarket heads 600 hp TPI motor on 12 psi of boost. In mine, I'll use the same motor but with a short runner intake with a matching cam. I'll spin mine to 6500 rpm instead of your 4500 rpm with 12 pounds of boost and make over 800 hp. TPI is just not competative with shorter runner intakes.

Given the choice, I'll choose the extra 35% power and finish the 1/4 a full second ahead.

 

Given the fact that my main concern is quarter mile time and on a budget, what are your thoughts on me switching to carb?

 

You could always go to a Holley Stealth Ram. It would probably be about the same money. Just a thought

 

Well said 83 crossfire TA,

89IROCZZ4, you need to let us know what you are running in your fuel system and how are you controlling the engine. here's some examples, Stock ECM, DFI, FAST,.... FMU, MSD6BTM, superfueler...etc.......

I'm guessing that you are running the stock ECM, stock fuel system w/ in-line ATI pump, and the ATI supplied FMU...

I bet that you'll find you are lossing alot of timing because of knock retard and/or belt slippage...you need to get ahold of a scanner and see what your engine is doing, also a boost gauge and fuel pressure gauge are very handy.

later
larry

 

Well, then I’m not kidding when I say you’re wrong.

In his example he’s making much less power then the TPI intake could support without being a restriction. Assuming that his engine is tuned as well as possible for his current combination, in his example he has at least 2 obvious things that are much greater restrictions to making power (the heads and lack of fuel).

for most engines the greatest deciding factors of what the torque curve looks like is the cam selection and engine size. The cam determines most of the shape of the torque curve, the engine size determines the area under that curve. Less important is the actual breathing ability of various engine parts, primarily heads (less important in determining the curve but more important in determining the ultimate limit, if they aren’t big enough it will just stop working, and in determining responsiveness it they are too large). After that would come any scavenging effect you get from the exhaust.

Intake runner harmonic tuning is only worth a 3-7% change in the torque curve MAX. That is all the extra filling you can get from an intake port optimally tuned to use the harmonic reflection in the intake. It’s enough to feel but not usually enough to do much with.

Actually, there is an overriding factor in this example. The boost. He’s supposedly running enough boost that it should make about a 50% difference in his torque curve wherever he actually sees the boost.

Wrong.

I would build my engine with the smallest possible heads that would not prove a restriction over the TPI intake. Ones that would flow right around 200cfm at .500” (assuming that I was using a cam with about .550” lift), I’d even consider something as tame as a set of LG4 heads with a good 1.94/1.5 (or 1.6” exhaust if we’re talking supercharger rather then turbo) valve job, some pocket porting and possibly a little work on the intake port inlets (this assumes that I can get the compression to work out to a usable #). That would give it much faster response off boost, it would build boost faster, and have better overall efficiency and drivability.

And yes, that setup would fall on its face by 5K rpm.

You stick your short runner intake on that and any cam you want and the engine will still fall on it’s face by 5K rpm, will never see the same low and midrange (because the cam and intake will just start working as the heads are dieing), and make the same peak HP with the same amount of air pumped by the compressor, so although your dyno peak will be the same your combination will be slower and less drivable.

If I were to stick massive heads on the thing I would run a matching intake. It's all about the combination of parts and in his case the TPI is not one of the parts causing the problem.

 

I can't believe I just sat here and read that whole thread.

If you put small heads on then replace the intake your car will still fall flat up top. yes

If you put good heads on it and a good intake its makes more power up top. no way. for real?

please tell me that's not all you two are saying?

The worst thing is, even after all that I posted a reply.

 

Go take it to the dyno.its worth every penny.theres no use in speculating ,your wasting your time.:lala: :lala:






dave

 

That is what I said a while back!

 

Hey 83 Crossfire TA,
I have a question and it is in no way meant as an attack. What makes the ZZ* heads no good? I just can't understand that. Aren't they part of the reason the ZZ4 is making 355 hp which is signifigantly more than a stock 350 TPI. Its more than just about any stock car's carbed 350 as well. Can it really be the cam and compression bump that is making that much more power in these engines? I have trouble comprehending that putting Lg4 heads on my ZZ1 would make it faster.

I am sorry to hi jack the thread guys but its related never-the-less.

 

betur4drustang...
To be honest with you the ZZ4 heads are a better FI head than carb head. They also need a good bit of work to perform in a TPI car. The long runner takes a good bit of horsepower from the motor. To take full advantage of the heads you need to run a little bit shorter runner. That will give you good HP and great torque.

 

well, an stock LG4 head will flow in the 190cfm rage (intake in the .400-.450” lift), where the ZZ* heads will be in the low 170’s under the same conditions.

What’s wrong with them? Well, ****ty port design and just as ****ty chambers. If you ever get the opportunity compare them (even pics of them) to a set of vortec heads (which consistently flowbench 50-60cfm higher at similar lifts) and you’ll not only see a superior port design but a chamber that is light years ahead.

Slap that set of iron vortecs on the same combination as the old aluminum head and you’ll see more power, better mileage, broader power band, and it will be less prone to detonation (you’ll be able to run leaner mixture and not have to run nearly the timing to tune for max power, even if you can manage to make it a fair comparison and make CR’s the same). Hell, look at the newer ZZ430 engines… very similar to the ZZ* engines but with a set of fastburn aluminum heads (basically aluminum vortecs) and suddenly it puts out well over 400hp.

Now I bet that that ZZ430 would still come close to putting out the same power with a stock TPI plenum and runners + the SD vortec tpi base… The TPI setup would be a slight restriction and you’d have better performance with a better matched cam…

The only hope the original vetteL98/ZZ* heads really have is if you’re a killer porting wizard (lingenfelter actually got some decent #’s out of them) or just hog them out and give up on getting a good shape out of the ports or chambers.

 

I remember reading an article in CHP saying that the l98 heads suck & they advised not to use them unless you get them really cheap! On my 87 vett, I had the engine rebuilt, heads ported. I could hardly tell the difference with a larger cam! I put on a set of Tickflow's ....It woke it up like BAM!

 

wow.

Perhaps it is a lofty goal, but I am hoping to get a high 11 with slicks and after tuning. All I know is on street tires and before tuning and not knowing how to launch, it is a 12.8-13.1 car (via g-tech). Before the supercharger, I was running in the same times but higher mph. Before was 107, after, 113.8. That is the array of times at least. I know I can't put too much stock into gtech's mph, as I hear it is always high, and is probably dependant upon where you are. I have heard anywhere from consistant 2-3 mph higher, consistant 7-8mph higher, etc.

To answer your question, maniacc, yes, I am running the stock ECM, stock fuel system w/ in-line ATI pump, and the ATI supplied FMU.

Here are my mods:

ZZ4 Crate Motor
ATI P600B 12PSI Supercharger w/3 Core Intercooler
Custom Ram Air Setup (coming in a few weeks)
Edelbrock shorty Headers
Flowmaster Muffler (40 series)
Modified MAF
Rebuilt and beefed up 700R4 w/2000 stall
TB Airfoil
24 lb/hr fuel injectors
Removed a/c
3.73 gears
Subframe Connectors
Lower Control Arms (not installed yet)
Relocation Brackets (not installed yet)
Hi Flow Catalytic Converter
All Accel/MSD high grade ignition parts (8.5mm wires, cap, rotor, etc)
TB Coolant Bypass

 

like i said earlier, get ahold of a scanner and it will help you solve your big problems then you can get to the dyno for the fine tune.

later
larry

 

Thanks for confirming what the point that I was trying to make with the actual numbers. Seems like sometimes you have to beat people over the head with the truth and they still don't believe it...

 

Well, first, make sure that you’re comparing apples to apples. If you’re comparing g-tech #’s then compare g-tech #’s, they are not the same as track #’s.

Second, et improvement is mostly up to your driving skills and chassis setup, more HP doesn’t mean your et gets faster. MPH usually is a fairly good indicator of changes though. Based on your mph #’s I’m guessing that you were in the 300-350hp at the crank range and I would expect a 40-50% increase with 12psi intercooled. Based on that I would expect that using the same method you should be capable of running around 119 or better afterwords, which should be enough to run in the 11’s (traditional track time wise, I’d expect a low 11, g-tech wise I’d expect a high 11…)

A few things for sure. You don’t have enough fuel. Running the #’s on the top side of the possible HP #’s you’ll need to come up with about 138psi fuel pressure to force enough fuel through the 24# injectors to feed the possible 500hp that you’re trying to feed. You’ll also need a serious fuel pump to move that much fuel at anywhere near that pressure.

For that matter, even if you got larger injectors you’ll find that you’re in a somewhat weird range for your ECM. First, no matter what your MAF is limited to measuring 250-300hp worth of airflow, so even pre supercharger you probably weren’t tuned quite right. Either way, you’d need injectors in the 40lb/hr range to feed that engine at 12psi intercooled(I’d probably go with 42’s), which I haven’t seen anyone get working right with any of the factory ’85-’92 ecm’s on a V-8.

If you’re a tuning freak you could probably get it working very well using 30-36lb/hr injectors, a factory ecm and an fmu or possibly the setup that you’ve got now with a carrol superfueler in the place of the fmu.

Another thing is that if you’re actually seeing that boost and you’re as short as it sounds you are for fuel I’d expect the engine to lay down at higher rpm’s. Since you haven’t described anything like that I’d say that before you do anything you need to get some real #’s. I suspect that you’re not seeing 12psi at the intake. I have no experience with the specific kit that you’re using or how much air the compressor is capable of flowing, but if it is designed to run 12psi boost on a stock L98 I wouldn’t be shocked if you’re not seeing significantly less boost and less power on your ‘better’ engine (like to the tune of only a few PSI total).

Sounds to me like you need a boost and fuel pressure guage to start with. If you’re seeing reasonable #’s (say over 10psi boost and fuel pressure in the 100psi range or so), then you need to start tuning. I suspect that you’ll find that you’re not moving nearly the air that you’re suspecting.

 

Boost,Knock, and FP gauges are a must for tuning. Once you get those put it on a dyno with some good gas(extra insurance for those hypercrap pistons) to get your base line. Once you get it to a better tune and start seeing the numbers I'd look into a cam swap.

AS 83crossfire said, the heads are preetty crappy. Standard flow numbers are around 170 cc's. I'm sure the stall point is around 185cc's. They have very small runners made to keep velocity high which lends itself to making low speed tourqe.

The last thing I would worry about is HP! The design of the TPI motors are to build low end tourqe. Look into a FI TPI cam if you don't wanna or can't do the head swap. There is the potential for the tpi cars to do mid 12's n/a. I don't know what kinda cfm the blower is pushing, but I'm sure running that many psi it's like a marathon runner breathing through a straw during the race.

I'd also look into at least 36lb/hr injectors at a minimum. The 42lber's seem to run too rich down low and lean up top. With it tuned properly and 8 psi on there with the suspension optimized(maybe a little weight reduction) you'll be very close to your goals

 

I’m pretty sure that you meant CFM, not CC’s. Last set I saw on a flow bench made it to 176 and then stalled (it was right around .500” lift).

It’s too bad that he doesn’t have a blower that will build boost well down low. If he did it would have a brutal midrange (like to the tune of 600+lbft by 3K). I’ve thought about building something like that for my full size truck, using a TPI intake (mostly because they look cool and flow more then enough for what I need, but if I was hoping for something from the long runners they’d actually have to be longer) and a small turbo, something that would top out at about 400-450hp but would be fully spooled (somewhere between 10 and 14psi) by 1500rpm on either a 305 or 350 (305 mostly for better gas mileage).

 

uh oh I think I read something in there about the stock ECMnot being able to do something right.

I know what you mean but your going to hear it from that grumpy guy, it can do anything right?

finally you are talking about him going to get it tuned.

If he doesn't even have a boost gauge his not tuning it himself and may not know what tuning is.

From what I've seen with my D1 if he is making 12lb and the tune is off much it wouldn't running after a couple of g-tech passes.

boost doesn't play it puts holes in pistons and blows heads gaskets but mine makes 15lb oh yea and breaks cranks I've done that too.

 

Heh, I’ve known Grumpy/Bruce P. (in the online sense) about as long as there has been any real online discussion of car stuff. In general, even he’ll admit that once you get into the 400hp range with most of the ecms you’re about at their limit. Past that you run into issues controlling the necessary injectors and the fact that the programming just was never designed to work in those ranges.

And I agree with you on the boost thing, like I already said, I really doubt that he’s getting 12psi boost since at best the engine would be laying down up top, at worst (if it did it suddenly) he’d be eating pistons and head gaskets.