Over in the c-5 power adder section there saying headers make no differance when on boost because the cylinder pressure forces the exhaust gas out, the only improvement is a small amount of increase at low rpm when not boosting...mines in the shop now getting headers installed..I guess I'll know for sure this evening.


[Modified by lead foot 85 vet, 9:32 AM 7/9/2003]

 

:lurk:

 

I find this hard to believe. VEEERY hard to believe. Maybe they were talking about shorty headers which have been proven to not do much on ANY application. Afterall, there's still a benefit to the scavanging effect of the headers pulling the gas out of the cylinders so the piston DOESN'T have to do all the work. I could be wrong, I'm no expert, but even stock manifolds are restrictive against N/A motors, how could it not help???

I was thinking about doing headers and 1.6:1 roller rockers to get the exhaust out easier.

Do us a favor and let us know how the performance is with the headers.

:cheers:

 

well i will tell you what! i have a stock TPI system and TB and i have full lengths and 1.6 rockers and with my blower at 11#'s of boost she is still pulling hard at 6000 rpm...we shut it down on the dyno because she started to lean out and we all know tpi's start shutting down at 5000rpm or so mine was pulling hard at 6000? so i am sure the headers and rockers and my cam had to do some help i think it is a combo you have to have i mean dont go throw a huge cam with stock heads and exhaust and intake?

 

I agree..I just dyno'ed mine and peak hp was at 4600 rpm ....the supercharger takes the tpi out of play so it has to be exhaust restrictions, but I was reading in the c-5 section yesterday and thats what there experiancing

 

I won't slam anybody, but I'd be leary of what's learned in the C5 f/i section. Most of those guys don't turn their own wrenches. To the ones that do :cheers: but most pay LPE to do the install.

Heck, just the other day there was a thread on there whether someone should put a boost and fuel pressure gauge on their s/c'd C5. Ummm, I think to us C4 guys that's pretty much a no brainer.....but about ~40% C5 guys said it's a waste of time. :eek: and no one else even suggested that they'd better do it!

 

yeah I read that too...

I have 2 things to say.

1. The LS1/6 is different then the L-98 or LT1.
Im sure the exhuast side of that car is better.

2, the L-98 can defently gain from a set of headers. I often go back to the stock exhuast on my L-98. With my cam, heads, and super ram, it chokes the crap out of it. Im going to say an honest 70 HP is lost through the stock exhaust based on how bad a friend of mine pulls on me.
I cant run the 1.6 RR on this combo as the exhuast glows red when I put them on, but runs great when I have my headers on. And with the headers and no cats, I pull on my buddy.

I have an N2O set up I have not installed yet, I would not imagine spraying it with the stock exhaust on it. And I feel the same thing about a supercharger. after looking at the L-98 manifolds the exhuast just cant get out.

 

<------- :lolg: are you kidding me....that is like the first thing i did was get my boost and fuel gauge? yeah alot of those guys on C5 have the Bling bling to spend to have people do there work? i mean if i have the money i will pay for some one to do it but on the other hand when i was strapped for cash me and my boy Tim AKA TIMMY we were about to plot on pulling my motor at his house on a weekend and then on the next weekend throw it back in? Those guys over there have nice cars but they come at a pretty price! But yeah turning wrenches tells alot of a person and there dedication on how much they love there car/s!

 

well they didn't finish it today but I learned something interesting did you know up to 85 corvette had double wall exhaust pipes.........for heat shielding........the mechanic said they quit doing it because the inner pipe would rust and rattle inside the outer pipe.........looks like I,m getting new pipes too, no wonder l98s like bigger pipes there not actualy 2.5 there 2 inch...........maybe I should wait and try just the headers first just to compare the differance.

 

Oddly, I stumbled in here by mistake - I was looking at the C4 - For Sale section, since I'd like to have one again. I had a 96 LT4 that I wish I'd never sold, but anyway I'm one of those "guys on C5 have the Bling bling to spend to have people do there work" and I have some insight for you on the s/c headers deal.

First, the supercharger we're talking about over there is the Magnuson - a roots type as opposed to the centrifugal types you guys are probably familiar with.

What we're finding is that the Mag was designed for the LS1 with standard heads and cams. If you put a Mag on a Z06, or head and cams car, you're near the upper limits of the Mag's ability to provide the right amount of boost.

So, what you gain from headers in terms of exhaust efficiency, you lose because the scavenging reduces the boost.

As for who turns wrenches, the Magnuson is a relatively simple install. But as I mentioned it's designed for the LS1. If you have a Z06, then you're talking about getting the PCM reprogrammed, along with some dyno-tuning to get what you can out of the Mag. The mag also requires a different hood, and LPE provides the hood (saving shipping charges and a trip to the dreaded body shop). By the time you add everything up, it's pretty much a no brainer to let the big boys do it and get a warranty.

Some of you guys need to go back and read your posts about the C5 guys. There's some stereotyping going on that's not right, and doesn't cast the best light on us C4 guys.




[Modified by Zoomin, 10:39 PM 7/9/2003]

 

Im not sure I see where you going with this?
Like this is a bad thing?

 

Anytime you can improve exhaust scavenging that is a good thing. With stock heads the air can;t get into the engine as fast as the blower puts it in and you get boost. If what you say is true all that proves is that the Magnuson is a poor choice for performance. With good heads you will lose boost and gain power because air is going into the engine then you just install a bigger blower and bring the boost back up again and make even more power Roots style blowers are the most inefficient of all they pump heat only way to make serious boost is to run it on methanol that will cool the charge. With a positive displacement blower you have good low end power but since you have to keep the boost low on gas you will not flow enough on the high end to compete with a centrifugal. In recent years a lot of R&D has gone into the centrifugal blowers and they have put the roots style back into the stone age unless you use ALKY to cool the charge. Sounds like the Mag that they are puting on those C-5's is too small to supply enough air to take advantage of the headers. Most people go to forced induction because they want more performance centrifugal will outperform the roots. Some point out that the centrifugal don't boost as well at 2500 rpm. When did you ever race someone and shift at 2500 rpm :crazy: Bottom line is if you have a blower that can flow what the engine can use the headers will give you a BIG GAIN In power. Before someone points out that John Force has a roots I will tell you that the above has already pointed out that we are talking about gas not methanol & nitro if you are building a race car you do things differently than for your daily driver. :leaving:


[Modified by black bart, 8:53 AM 7/10/2003]

 

Good for you, and someday I hope to also :cheers:

Correct me if I'm wrong, but the only way the scavenging effect can affect boost is due to valve overlap. That makes sense on a Head/cam car built for N/A performance where low RPM overlap is heavy, especially considering that's where a roots blower performs the best. This just proves you can't just slap a blower on anything. :cheers: If that's the case I'll have to agree that not only do the headers hurt performance, but the blower doesn't help as much as it should either.

Well, you are missing the big picture. If I had paid someone to put my blower on, I would have spent more money and saved more time right? EH! Wrong! If something goes wrong with it, (which everyone knows everytime you mess with your car something eventually goes wrong) I now know where everything goes and have an idea, if not know exactly what the problem could be. People who pay for installs only end up spending more money down the road for troubleshooting and fixes. Why do you think LPE offers a warranty, and what do you think you're paying for with their kits. The warranty is just extra money they charge as an insurance policy.

I agree that the actual post about the exhaust should have been posted in this thread to be referenced before we made our opinions known. However, we were only poking a little fun about the "Boost-no-boost gauge" debate.....you have to admit, that is pretty damn funny and doesn't make the C5 guys look good as much as we probably make the C4 guys look bad. :lol:


[Modified by vvv90, 9:03 AM 7/10/2003]

 

I haven't read up on any of the issue of C5 SC and headers, but I hope that people aren't saying it is a waste of money because they are losing some boost. Boost is really created by back pressure of the engine. If an engine has less back pressure, than it can flow more air which equals hp. So for example if the supercharge is spinning at the rpm and create less boost than it is flowing more cfm, this is a good thing. Not all boost is created ie 5psi of boost can be less effiecent than 4.5 psi of boost even with the same compressor. Less boost with the same compressor will usually produced less heat as well.

 

lead foot, are you, or do you have cats on it?

 

Yes, the amount of air you flow and the amount of fuel you burn creates horsepower, but in this example we're talking about exhaust back pressure. Boost is created with "engine" backpressure as a general statement. More accurately you want your intake pressure high and your exhaust pressure low if non-existent. Evacuating exhaust gases as efficiently and expendiantly as possible helps make boosted applications efficient power plants. As long as your blower can keep up with the CFM requirements of the motor which seems to be the problem of ths C5 Z06 with a mag blower.


[Modified by vvv90, 9:38 AM 7/10/2003]

 

I think poor exhuast scavenging can affect boost (raise the psi in an inefficient way) if some of the used exhaust gas are creating a restriction in the intake path to the combustion chamber. I used 'engine' back pressure, because the intake and exhaust path aren't a totally seperate process. i am not alway the best person explain the techincal stuff, I under a lot of the theory's, but I have a hard time with words...

 

No you're right. I'm not expert either, but we're on the same page. :cheers:

 

BINGO Give that man a cigar. You got it right.
To give you a little insight on how a roots style works a friend bought a 68 vette and he had a big block built for it by a guy that lives here and they won like 16 nationals in ATPA he quit pulling but had a lot of stuff laying around so he built my friend an engine just like they ran in the pull tractor. I told him it would not work on gas but they spent four months tuning and give up it ran hot so now it is running on methanol. Cam won't idle below 2000rpm he won't be able to drive it anywhere without pulling a trailer with a couple barrels of alky. You have to squirt alky into the bug catcher to get it started and then flush the fuel system with marvel mystery oil when you shut it off because the methanol will corrode the alluminum in the fuel system. When we had it running last Sunday it was hot and humid and the alky made the blower so cold the water was running off of it from condensation. When you put your hand on the blower it felt cold this is what it takes to run a roots and make power they are not good on gas. Now you now why I have alky injection on my car. He has no plans for racing it at the track he thinks he is going to drive this dam thing on the street :crazy:

 

Well from what I have read and what I have been told is that roots styles are good when running alk or meth but gas it just gets to hot for the power you want to make? BUT if you want to make any kind of boost you should not rely on back pressure to make good boost...if you are adding mufflers and keeping stock exhaust manifolds you simple need a bigger blower! I know if I slapped my cat and mufflers I would probably make 13#'s if not more but since I am running full lengths no cat no muff's and straight exhaust system I still make 11#'s at 5600rpm and rising? It is about how much air you can move and if that roots blower on that C5 cant move the air then don’t spend the money I know on this site http://www.dynopro.com there is allot of C5's with blowers making killer power in centrifugal blower and there are vipers with roots only making like 460hp to the back wheel? So it seems to me that roots are good for NHRA and hard-core class events but if you want a daily driver go with centrifugal blower?

As for turning wrenches...whateva :yawn: