Basics:

*1998 Chevrolet Camaro, with a forged LS2 low compression motor (8.5 - 1 compression)
*6 spd manual with (turbo unfriendly) 3.90 gears, Moser 12 bolt rear end
LS6 intake, 60# fuel injectors, MSD Ignition Coils
*Stock exhaust (no catalytic converters)
*Ultragate 38mm Wastegate with 5# spring, STS BOV, FMIC, Stock but bored throttle body
*STS rear mount GT-67 ball bearing turbo with an AR.91 housing
*AFR's 11.8-12.1 at WOT (no boost in 1st gear)
*HP Tuners shows a WOT Ign Timing of 20 degrees
*Full Boost coming on at 3,500 rpms
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1. What gear set would you FI guys recommend for this build?
2. What sort of AFR's should i be running on 91 premium octane fuel?
3. What sort of ignition timing should i be running on a (no-methanol) low compression (8.5-1) all aluminum motor?
4. How can i build full boost at lower rpms?
5. Any other advice on getting this car to run more efficiently with a turbo?

 

just throwing it out there theres a reason many dont go with sts kit and just build there own rear mount systems. they are charging an insane amount of money for something that advertises a 100 hp increase with having you spend a grand more for 150 hp. you can get a procharger or whipple/kenne bell for the same exact price and make ALOT more power, and never have to worry about spooling/turbo lag. but if rear mount turbo is your cup of tea, build your own, alot of the sts stuff in the kit is garbage, for starters the oil pump is too weak and causes problems. do a search on here for sts builds.

 

i always find it interesting that people just assume superchargers reach full boost instantly. superchargers will absolutely start sooner but when you get into higher boost numbers they're gonna build up like a turbo maybe peak sooner too depending on your setup. i've been contemplating how things would have been different with an f-1a myself. but i digress. sts kits are a decent start since they take a lot of fabrication out of the question,some stuff is lacking but they're better than they used to be, but yes they are expensive and if you want more power you're gonna have to make the appropriate upgrades like everyone else. if you're running only 5psi and peaking at 3500 that is pretty bad. your a/r is definitely too big even for a 6.0. ideally afr should be 11.0 under boost. your oil return line should be larger than your feed line and consider using a 1qt catch can to hold your turbos oil instead of feeding it into the pan this can help with flow so the pump doesnt have to fight the crank case pressure. get yourself a boost reference fuel pressure regulator and make your setup return from returnless. (it really easy). i'm running stock 3.42 gears but wouldnt go higher than 3.55, that should be an otion for moser. 8.5 compression is very low for only 5psi that can be hurting you a lil too but its too late to fix that.

 

watiing to see the responses as well on this. im close to putting mine together aswell.

 

I want to build my own as many of us do just not sure in were to start or how do we go on about building it ourselves?

 

Doing your own custom kit is gonna be a bunch of cut and guess. If you're doing your own welding and cutting then cost would be lower but certainly more guess work.

 

Start at the back and figure how to mount the turbo then work your piping up to an intercooler and on to the intake

 

Low 3s on the gear.
Wrap all of the hot pipes and use stock manifolds.
Mid 11s AFR with no more than 14* to be safe.

 

if your a hack then yes... cutting and guessing and then recutting and then buying more crap and then doing it all over again is a sign of a true novice and will only lead to disappointments, failure, and wasted time and money.

a smart fabricator will, "like your daddy told ya", measure twice, cut once.
in any trade requiring fabrication, attention detail is key. you dont go in half cocked. theres no guessing if you research and look at the whole picture.

 

I just took an STS kit off to go to a big front mount. A couple things stick out too me.

1. A gear will help tremendously with spool/load. My car is a 6 speed as well. I had 4:10s from my last build in and bareley loaded the turbo until W.O.T. I changed to stock 3:42s and got spool at 3k. Wished I would have went lower though maybe to a 3:23/3:08. Maybe a 2:97 but then again I am a street car I wanted to have long gears. They will get your boost up way sooner though. They do more than you think. literally night and day difference.

2. I would yank that GT-67 off and throw on a more efficient turbo. Dont listen to the STS people that that turbo is big enough. You have a forged LS2 you could leave that turbo with the wastegate unplugged and still not have your desired power. I would look into something without a 68mm exhaust wheel. That turbos V.E is nowhere near where it is suppose to be for a 6.0 even if it were front mounted. Get into something more like a S375 or a PT7675. It just lets more exhaust out. Each pound of boost will make more hp than the current turbo because it isnt being bottlenecked at a 68mm turbine. I know it sounds like alot but you will have way better top end power and it will be worth it when you are done.

3. The 38mm wastegate. Not enough W.G IMO for a 6.0. On 5 psi you are opening the gate immediatley and trying to get alot of exhaust out of a little hole. Alot of people with remote mount setups use 2 wastegates just to let it breathe better once they open. All about getting the exhaust out under boost like stated before.

4. Ditch the MSD coil packs. They suck unless the tuner knows how to make them work right. I have little experience with them all I know is all my friends that bought them threw them away after. Stock ignition is plenty for us. If you want/need more switch to truck coils.

5. A/F looks nice I generally like it under 12.0 all the time. Try backing the timing out a little bit maybe 16-17 degrees. I know of people that run like 13 degrees. I could not tell you why but they claim it will spool faster. Depends on the setup though. Seems low to me but I am just giving suggestions.

 

BTW I just seen your sig. If this is the car with the 402 c.i in it DITCH THAT TURBO A.S.A.P!!! Your cubes are eating that turbo alive. I couldnt imagine the back pressure. the exhaust cannot get out. Regardless of that though the compressor cannot possibly support the CFM your motor moves with those AFRs and bigger cubes. With an engine like that to make even decent power you will have to go to s80 minimum/PT88/T88 with a 4" downpipe to even get started lol. The motor moves too much air n/a to even dream of using that turbo. Trust me go dual wastegates change to 3:23 gears get a PT88 and make sure you have the fuel lol. You have a ton of potential sitting it just unfortunatley has a potato in the tailpipe. Hell I bet that charge tube has vacuum on it 90% of the time lol. The motor is using more steam n.a than that turbo can support.

 

Wow..i am getting the feeling my build is significantly underbuilt

Where is the downpipe on our cars? I bave a wastegate, blow off valve, and air inlet...that's it.

Is there a single bigger wastegate i could use versus 2 of them?

I just ordered a set of 3.42 gears...will these be sufficient or should i go with a 3.23 gearset? Is there going to be a huge difference between the 2 gearsets?

And yes i have an 8.5-1 compression forged all aluminum LS2 4.2ci motor...built this way with a turbo cam so i didn't have to worry about methanol injection. I am just looking into a new 2 bar MAP sensor so we can get different tuning on the car to allow for more spark "pre" boost.

I think i'll also have to upgrade my Racetronix single 255lph fuel pump.

I'm going to have to look into cost for an 88mm turbo and see what that will run me. Are there any recommendations on turbo supplier (brand name)?

Any other suggestions are more than welcome...thanks again for all of your recommendations.

Ryan

 

You will need at least dual 255 pumps. 342 or 323 will work just fine. Just slight difference. For a 402 ci hell I would use the 323.

I THINK. Tial makes a 60mm gate. I would just run another one of what you already have though for the $$.

For a turbo I bet a Borg Warner s80 would work well rear mounted. A precision 88mm would be badass. Hell even a Precision 76/75 (PT76GTS) would work well rear mounted. There is a GTO local to me with a 408ci running a 7675 rear mounted and runs awesome. Unless you plan on using a TNX-88 stay away from T netics stuff. Good turbos/company not knocking them but the exhaust housings/wheels are a little small for your cubic inch. Even rear mounted. To make the power you want is going to take alot of fuel/turbo. There is just no avoiding it.

Just stick to t4 exhaust housings and TRY to get something with a turbine bigger than a 68mm. For compressor side you will need at MINIMUM a 76mm to just get started. It takes alot more with big c.i. little motors are way easier to turbo.

If the turbo is too small it wont be efficient up top and you will lose races like mad. Even if you are making dyno power. Turbos are hard. They are a different animal than blower cars because you have to take into account how much the exhaust is backing up.

 

so how goes it?

 

I'm tempted to do my own, my only problem would be how to spec the turbocharger to suit. Cant get my head round the differences in sizing a front mount compared to a rear mount.

 

well first off, how bigs your motor and how much hp you aiming for? also what kind of driving you plan on doing with it?

 

1. What gear set would you FI guys recommend for this build?
3.42

2. What sort of AFR's should i be running on 91 premium octane fuel?
how much boost and how much timing? mid 11's

3. What sort of ignition timing should i be running on a (no-methanol) low compression (8.5-1) all aluminum motor?
how much boost are you going to run, and if 15psi or less, why such a low compression? 16 degrees maybe more.

4. How can i build full boost at lower rpms?
wrap all exhaust & turbo, get that 3.42 gear, will help. Two step, etc. for launching.

5. Any other advice on getting this car to run more efficiently with a turbo?[/QUOTE]

read my build. how much power do you plan on making? That LS2 is air hungry, that 67mm is mighty small for that engine, that should also help push exhaust to it and spool it. Your ball bearing helps versus journal bearing regarding turbo response. You say stock exhaust, do you still have that Y-pipe with the flat section in it? switch that over to an SLP 3 inch piece.

I see you have a 38mm wastegate, that is good for up to a TC76 unit, so don't worry about upgrading that. What is your size of your BOV? It doesn't matter what brand it is, get a tape measure or a caliper and measure that puppy, then look online at the various drawings or email the manufacturer to check your BOV size. I'm running a 38mm wastegate and 50mm BOV.

Also, are you just running off the wastegate spring pressure? I recommend getting a boost controller, whether E-boost or HKS EVC something. I purchased the HKS EVC-S, and it is simply amazing what a boost controller can do versus just a spring. I'm running an 7LB spring with my boost controller.

I will have to do some logging and checking and get back to you on my spool times and RPMs. the biggest kicker is a rear mount is a rear mount and a front mount is a front mount. Hotter exhaust gases equals faster spool, so do not expect to crank up a rear mount and then immediately race someone. you gotta let it get warm and up to optimum temperature.

people will bash rear mounts. You choose what you choose, and different advantages versus disadvantages of each. Having to remove AC or spend hours doing spark plug changes. We do what we do. let me know if you have questions, I hopefully should have answers. Also, if it is still there, look for Zombies build & Longrange4u build.

That 67mm will push that ls2 6.0L to ~550hp at most. work out these kinks and you should have quick spool & etc on that small turbo. A TC72 mm or even TC76 would suite that motor much better, but keep chugging away at this the way it is. I want to know updates.

 

I'm having a hard time understanding your worrying about methanol injection & compression. Boost wise, PVT=PVT (1&2) so IAT temps are dependent on ambient temp + pressure. Now getting into the combustion chamber temperature is a hole different ball game.

as far as upgrading your racetronix 255, with that 67mm, I doubt it.

88mm turbo...uh that is a little big, but what plans do you have for the car? Fun driver & some track, or all out track and racing ?

If you plan on competitive racing, either get an auto or put a two step and etc on that car.