Official STS help thread
Where manifolds become less efficient is when they restrict the airflow of the engine... that means you are loosing HP at the engine to gain efficiency at the turbo. LT's will work with a rear-mount turbo... but with less efficient volume of gases reaching the turbo. Wrapping will help but not completely solve that problem...
Joined: Jun 2004
Posts: 1,501
Likes: 7
From: Ft. Irwin, California (But Virginia is home)
Yes, but it may start an argument again, something I have been trying to avoid on this subject. But here goes:
First, wrapping even the stock manifolds will gain power and lower spin up times. I'm not going into the physics again, except to say that heat is the friend of every turbo. The more heat, the more power.
If you put headers on the car, you must absolutely wrap them, for the same reason.
Where headers will gain you more power is when the stock manifolds become a large restriction in the whole air-in-air-out system. An engine is only an air pump, after all. If you increase the flow (such as increasing boost) then you should go with the wrapped headers. It is a type of volumetric flow physics, except you are using gases rather than fluids, which you can Google if you so desire. Just avoid the differential equations, they are a bit advanced.
Hope this helps.
BTW, if the car is not a dd, I would double wrap the headers to retain more heat.
First, wrapping even the stock manifolds will gain power and lower spin up times. I'm not going into the physics again, except to say that heat is the friend of every turbo. The more heat, the more power.
If you put headers on the car, you must absolutely wrap them, for the same reason.
Where headers will gain you more power is when the stock manifolds become a large restriction in the whole air-in-air-out system. An engine is only an air pump, after all. If you increase the flow (such as increasing boost) then you should go with the wrapped headers. It is a type of volumetric flow physics, except you are using gases rather than fluids, which you can Google if you so desire. Just avoid the differential equations, they are a bit advanced.
Hope this helps.
BTW, if the car is not a dd, I would double wrap the headers to retain more heat.
I'll add my $0.02 that wrapping the exhaust DEFINETLY lowers spool times. As far as stock manifolds vs. LT headers....I've never had the stock manifolds on w/ the turbo. Can't test the difference either as the wife gave my stock manifolds away at a garage sale when I was in Iraq
Anyhow, I haven't had probs w/ the LT's.....but they are Jet-Hot coated. Think that for a DD car LT's are fine. The potentially longer spool time is offset by better breathing for the engine when NOT in boost (which is most daily driving for me). So...if you have LT's I wouldn't dump them because you have a STS. I would recommend using coated LT's though
BTW, my current set-up (w/ LT's) will hit 5PSI in every gear by 5K RPM (1st included) and once the exhaust is good n' hot will start to build positive pressure (ie boost) as low as 2350RPM in 3rd-6th gear at 50% throttle or greater
It seems to take a couple WOT blasts to build the exhaust heat up good. It's also boosting much faster since converting from the "stock" tuning to 2-Bar SD. Another topic, but being able to map the fuel for all the different boost cells has really helped to decrease turbo lag. Last edited by Schantin; Jan 1, 2008 at 10:57 PM.
How is the clearance under the car with these sts kits?
I have my t-top hump removed, would putting it under there give more clearance?
Also has anyone ever mounted the air filter inside of the car in the trunk area?
I have my t-top hump removed, would putting it under there give more clearance?
Also has anyone ever mounted the air filter inside of the car in the trunk area?
O.K., I will try to answer all responses in this one reply.
First, Let's discuss turbochargers. They are driven from 2 types of energy: the volume of the exhaust gas, and the heat of the exhaust. That is why a front turbo will outpower a rear turbo 100% of the time, it loses almost no heat because it is bolted right on the exhaust manifold. And they use the cast iron manifolds because the cast iron (thicker) will retain more heat than any header (thinner).
The poster who said that hot gases have more volume than cool gases is correct. However, that is not why you wrap the exhaust. You wrap the exhaust because it helps the exhaust pipe (thin) retain more of the heat. The more of the heat energy reaches the turbo, the faster it will spin up and the more boost you will see, with absolutely no other changes to the system.
Let's take that for a given, for the moment.
Say you are losing 50% of your heat energy because the exhaust is not wrapped (these numbers are a swag and have no basis in fact, but there have been people who have proven on the dyno that wrapping does increase power). Let's say you put one layer of wrap on the exhaust and gain back 25% of the heat energy. You see the increase in power, but the wrap is still too hot too touch. Conclusion: some heat is still being lost through the wrap. Let's say you put a second layer of wrap on the same length of exhaust and gain back another 10% of the heat energy. You are still losing 15% of the heat energy through the wrap, but have made a smaller (but not totally insignificant) gain in power. Is that incremental gain in power worth the $100 you have to spend for the second layer? You tell me.
The only way to prove it is on a dyno, and I am not sure that anyone has ever done this.
The same physics apply to headers, only more so because they are so much closer to the source of the heat (the exhaust ports of the engine). Thus headers have a greater potential for loss of heat. If anyone has ever had a car that they put headers on, they noticed that the engine compartment is now hotter, because of the increased heat loss versus cast iron manifolds.
Perhaps the best STS compromise would be cast iron headers. IIRC, some cars came with those; they were not as efficient as tubular headers, but were more efficient than a "standard" exhaust manifold.
If you want more information on turborchargers and the types of energy that they utilize, find a turbocharger engineering forum and start asking questions. That is what I did when I first bought my STS system, and how I came up with the idea of wrapping the exhaust. You are welcome to do the same and post your results.
Peace
First, Let's discuss turbochargers. They are driven from 2 types of energy: the volume of the exhaust gas, and the heat of the exhaust. That is why a front turbo will outpower a rear turbo 100% of the time, it loses almost no heat because it is bolted right on the exhaust manifold. And they use the cast iron manifolds because the cast iron (thicker) will retain more heat than any header (thinner).
The poster who said that hot gases have more volume than cool gases is correct. However, that is not why you wrap the exhaust. You wrap the exhaust because it helps the exhaust pipe (thin) retain more of the heat. The more of the heat energy reaches the turbo, the faster it will spin up and the more boost you will see, with absolutely no other changes to the system.
Let's take that for a given, for the moment.
Say you are losing 50% of your heat energy because the exhaust is not wrapped (these numbers are a swag and have no basis in fact, but there have been people who have proven on the dyno that wrapping does increase power). Let's say you put one layer of wrap on the exhaust and gain back 25% of the heat energy. You see the increase in power, but the wrap is still too hot too touch. Conclusion: some heat is still being lost through the wrap. Let's say you put a second layer of wrap on the same length of exhaust and gain back another 10% of the heat energy. You are still losing 15% of the heat energy through the wrap, but have made a smaller (but not totally insignificant) gain in power. Is that incremental gain in power worth the $100 you have to spend for the second layer? You tell me.
The only way to prove it is on a dyno, and I am not sure that anyone has ever done this.
The same physics apply to headers, only more so because they are so much closer to the source of the heat (the exhaust ports of the engine). Thus headers have a greater potential for loss of heat. If anyone has ever had a car that they put headers on, they noticed that the engine compartment is now hotter, because of the increased heat loss versus cast iron manifolds.
Perhaps the best STS compromise would be cast iron headers. IIRC, some cars came with those; they were not as efficient as tubular headers, but were more efficient than a "standard" exhaust manifold.
If you want more information on turborchargers and the types of energy that they utilize, find a turbocharger engineering forum and start asking questions. That is what I did when I first bought my STS system, and how I came up with the idea of wrapping the exhaust. You are welcome to do the same and post your results.
Peace
Joined: Jun 2004
Posts: 1,501
Likes: 7
From: Ft. Irwin, California (But Virginia is home)
Sucks 
Honestly, my driver side header pipe from the collector is a couple mm lower than the lowest STS pipe....BUT I have the TRT modded under axle pipe from the turbo and a FMIC. W/out either, the front pipe comes within 3 or so inches of the ground and the rear over-axle pipe dips almost as low.
Thought about it, but having to cut a 3" diameter hole in the trunk floor has kept me from trying it
Honestly, my driver side header pipe from the collector is a couple mm lower than the lowest STS pipe....BUT I have the TRT modded under axle pipe from the turbo and a FMIC. W/out either, the front pipe comes within 3 or so inches of the ground and the rear over-axle pipe dips almost as low. 
Not quite but close... heat only directly effects the volume of the gases thus the efficency of the air through the turbo... the turbo itself is just a turbine that spins when gases pass through it... it dosent care about heat. An efficient turbo is a hot turbo... but that is more a side effect of the gases rather then a "requirement".However, that is not why you wrap the exhaust. You wrap the exhaust because it helps the exhaust pipe (thin) retain more of the heat. The more of the heat energy reaches the turbo, the faster it will spin up and the more boost you will see, with absolutely no other changes to the system.
Ummm you kinda contradict yourself here... That IS why you wrap your exhaust... to maintain the gas efficiency (volume) as much as possible as it transits your exhaust to your turbo.
The same physics apply to headers, only more so because they are so much closer to the source of the heat (the exhaust ports of the engine). Thus headers have a greater potential for loss of heat. If anyone has ever had a car that they put headers on, they noticed that the engine compartment is now hotter, because of the increased heat loss versus cast iron manifolds.
I'm just going to go with the assumption that even though I have a pretty good size cam for a turbo setup and pushing 12#, and will only be trying for mid-500's, there wouldn't be TOO MUCH airflow coming from the engine to be negatively affecting the all ready restricted path through the stock exhaust that does not occur with the LT's. Am I correct? Or does that just come out as jibberish?
Not quite but close... heat only directly effects the volume of the gases thus the efficency of the air through the turbo... the turbo itself is just a turbine that spins when gases pass through it... it dosent care about heat. An efficient turbo is a hot turbo... but that is more a side effect of the gases rather then a "requirement".Thank you... Physical Sciences 101
Ummm you kinda contradict yourself here... That IS why you wrap your exhaust... to maintain the gas efficiency (volume) as much as possible as it transits your exhaust to your turbo.
Ummm... I know what you are trying to say here.. but I would say that distance from the exhaust ports dosnt matter... only surface area of inefficient piping does.... If a header has 2x more surface area then stock exhaust... then even if you hang the turbo directly off the turbo (closer to the engine)... you will still loose more heat then you would through stock exhaust (further from engine) because it has less surface area to dissipate the heat.
And wiseass comments are not productive to the intent of this thread.
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Verdad Gallardo I concur, reocamaro. I suggest that those that question my statements Google on "heat energy turbocharger". There is lots of general information around that is easily absorbed. My first hit states "Other: Heat management on the exhaust is important on turbo engines. Heat should be kept in the exhaust gas for fast throttle response."
It's all out there folks.
Peace.
It's all out there folks.
Peace.
People have made alot of power using stock manifolds. I wouldn't change them out until you're well into the nines (See Zombie's setup). I would look into using GTO or C6 manifolds (nice pics and discussion here --> https://ls1tech.com/forums/showthrea...=837929&page=2) or porting and coating the stockers if anything until you are really going all out with a bigger motor and turbo. Of course where will that big turbo go? It's kind of crazy, but I've actually thought of using some of the space in the back where the t-tops sit...
So far this is what i got and help me out with this I would like to make somewere around 550 to 600. I have a stock LS1 with LT in a 87 IROC. I'm building a IRON 6.0L (Forged 370). So i should get stock F-Body or C6 manifolds and wrap them all the way back to the turbo. My Turbo is 67MM do I need more? I have a FMIC. Thinking of keeping the heads stock 317 upgrade springs. I'm think a speed inc cam or just get a custom one. Am I headed in the right direction. Any advise would be great. Oh and whats up Reocamaro When i get back from cruise i want a good rematch.
The information you found is because the efficiency of a turbo is directly effected by the temp of the gases passing through it. Again... the temp of the turbo is a side-effect of hot gases, not a requirement of the turbo itself to work well. Again.. its just a turbine encased in metal...
No hard feelings here bro... we are all rear-mount lovers
And I plan to run 8's on my stock manifolds... Somewhere in all of that gentlemanly bickering, I found my answer. If stock manifolds are good for 8's, I don't need to worry about thinking my LT's are going to show any benefit. And Grifter, Granted when I head back down to Virginia Beach you'll have your rematch. Actually, you'll have your match. That last thing, it was just a little jog. Maybe even catch you at the track in Richmond.
Somewhere in all of that gentlemanly bickering, I found my answer. If stock manifolds are good for 8's, I don't need to worry about thinking my LT's are going to show any benefit. And Grifter, Granted when I head back down to Virginia Beach you'll have your rematch. Actually, you'll have your match. That last thing, it was just a little jog. Maybe even catch you at the track in Richmond.
VA huh? I am moving out to Reston next year...
