Help me build a turbo system.
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Joined: Sep 2001
Posts: 212
From: Red Oak Tx
Help me build a turbo system.
I have been kicking around the thought of building a turbo system for my lt1 powered sonoma.It is currently a 383 with LE trick flow heads(2.08/1.65),11.5:1 compression,slayed mains and all forged goodies.I know the compression will need to be lowered and I will need a cam change.The truck currently traps 115-117 mph on motor and 130-132mph on a 250 shot of nitrous.Truck current weights 3400 lbs with driver.Im looking to trap in the mid 140s and in the 9 second range and need to know what I need to get there.
(1)How much boost would I need.
(2)What type headgaskets/bolts/studs would I need to hold that much boost.
(3)Do i need 1 larger turbo or 2 smaller turbos? What size for either combo? benifits either way?
(4)What wastegate,blow off valve and boost controller works the best.
(5)Can the stock pcm be programmed easily to work well with boost.
Transmission is a 4l80 with a yank 3600 stall converter in it.Im running 4.10 gears in the rear.I would guess I would need a gear change also since im crossing the line at 6500 at 130 mph now,Or i could just shift into 4th gear.This trans would definately hold it.
I still drive this truck on the street from time to time since its still street legal and would like to keep it that way.
Ive done lots of searches and Im doing lots of reading,I would just like some imput from the guys that have already done it and know what will work.
(1)How much boost would I need.
(2)What type headgaskets/bolts/studs would I need to hold that much boost.
(3)Do i need 1 larger turbo or 2 smaller turbos? What size for either combo? benifits either way?
(4)What wastegate,blow off valve and boost controller works the best.
(5)Can the stock pcm be programmed easily to work well with boost.
Transmission is a 4l80 with a yank 3600 stall converter in it.Im running 4.10 gears in the rear.I would guess I would need a gear change also since im crossing the line at 6500 at 130 mph now,Or i could just shift into 4th gear.This trans would definately hold it.
I still drive this truck on the street from time to time since its still street legal and would like to keep it that way.
Ive done lots of searches and Im doing lots of reading,I would just like some imput from the guys that have already done it and know what will work.
Last edited by slammed98gmc; Mar 17, 2007 at 07:01 PM.
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Joined: Jan 2007
Posts: 73
1. 20-24 lbs of boost and race gas
2. Some people can use the Fel-Pro gasket here, some opt for copper, some Cometic. First, I would try the inexpensive route. I would use ARP studs.
3. Many classes don't allow two turbos and investigate this if you plan on competition. Otherwise, two smaller, parallel turbos are usually used when size constraints restrict a single installation or quicker spool up is wanted. Personally, I don't see the big out-rage with lag of a 1200 horsepower single turbo. Newer turbo technology for the performance automotive sector has produced refined models which don't suffer the lag of large, old turbos. So, two smaller turbos of comparable net size would spool a little bit quicker, but you have two of everything; this can look cool, but it can start to be a pain in the a$$ really quickly. For two smaller turbos to make ~1000 crank horsepower, you will want a 58 to 61 mm compressor with a .69 A/R T4 housing with P-trim wheel. Don't buy anything that says T3/T4 or hybrid for your engine. Some examples of possibilities, that would be good for your engine, from Turbonetics would be: T04E-57 trim, T04E-60 trim, 60-1, 62-1, T-58, T-61. Personally, I would opt for the 62-1 or T-61 models. However, if you wanted to run a single (not sure if it would fit anywhere in your truck), you will want a 76mm turbo or larger. Some models would be T-76 P trim or MPS trim, and moving on to larger units: T-80 and T-88. Turbonetics isn't the only game in town; Precision has an older unit which is the PT-88 but still known around the boards for making big power. You could also move to the Garrett line with a G42-76 for 1000 horsepower or go larger with a big gun like the 88mm GT55. Again, these turbos are huge, especially the 47 and 55 models, lol. Like, literally, huge. For your truck, I am thinking you will need two smaller turbos; then again, I haven't seen under the hood of you truck. Have pictures? The last time a saw a SBC S-10 I saw two perfect places next to the trans, or there about, for two turbos.
4. Wastegate sizing goes like this: the more air you need to move around the turbine (not make boost), the larger of a wastegate you need. Of course, you must also consider whether you have restrictive headers, low-back pressure down-piping, restrictive turbine housing and wheel. For twins, I would use a 38-40mm wastegate. Depending upon which model you choose for a single, you will want a larger (60mm) wastegate. With regard to a blow-off valve, they all seem to be rather ubiquitous, simultaneously! I think the latest trend is choosing one that is the right color, the right shape, and or makes the most noise so people shutter in fear and empty the streets as your ride escalates you to super-stardom/super-macho. lol As with everything, some are garbage and price can be congruent to quality. Most all of the boost controllers perform well, some having specific features that some users require while others do not (e-boost 2, Innovative MSBC, I think the Apexi AVC is supposed to be useful, but don't take my word for it). Many times, the boost controller's reputation comes down to the guy setting it up knowing WTF he is doing or not. That seems to take precedence in a lot of end-user opinions on the internet.
5. When you tune the stock PCM for this, the MAF is no longer reading; it has reached peak capacity in the PCM. So, you basically tune the AFR through the PE tables and your wideband. Of course, this presents two problemos for us: with your fuel curve static, so must be your boost curve and atmospheric changes are not readily adapted to. In effect, you are stuck with the boost curve you setup and if you tune the car at 40*F at sea level, and then take the truck up into the hills on a warm day, you will run rich (and lean if vice versa). For a street car, this sucks —period. Some people will try to convince you otherwise, telling you they have nine-second cars on the PCM as they dazzle you with brilliance; this is a red-herring. Moderate boost on the stock PCM is not only a cobbled implement, it is very coarse in resolution. You have to increase the interval of your MAP axis to introduce the high MAP readings of the boost and this makes things coarse for a street vehicle. If you want to tweak your tune at the track, or the tuning atmosphere isn't much different than the track atmosphere (how often is that?), this is not really a big deal.
On turbos, you want a lower gear. I would use, at least, a 3.73 gear You can go even lower if you have short tires. What size tires are you using, anyway? The quicker you can load the engine, the quicker the turbo is going to come on-board. In a nutshell, turbos love load (something the bastard child belt driven supercharger could never do
).
2. Some people can use the Fel-Pro gasket here, some opt for copper, some Cometic. First, I would try the inexpensive route. I would use ARP studs.
3. Many classes don't allow two turbos and investigate this if you plan on competition. Otherwise, two smaller, parallel turbos are usually used when size constraints restrict a single installation or quicker spool up is wanted. Personally, I don't see the big out-rage with lag of a 1200 horsepower single turbo. Newer turbo technology for the performance automotive sector has produced refined models which don't suffer the lag of large, old turbos. So, two smaller turbos of comparable net size would spool a little bit quicker, but you have two of everything; this can look cool, but it can start to be a pain in the a$$ really quickly. For two smaller turbos to make ~1000 crank horsepower, you will want a 58 to 61 mm compressor with a .69 A/R T4 housing with P-trim wheel. Don't buy anything that says T3/T4 or hybrid for your engine. Some examples of possibilities, that would be good for your engine, from Turbonetics would be: T04E-57 trim, T04E-60 trim, 60-1, 62-1, T-58, T-61. Personally, I would opt for the 62-1 or T-61 models. However, if you wanted to run a single (not sure if it would fit anywhere in your truck), you will want a 76mm turbo or larger. Some models would be T-76 P trim or MPS trim, and moving on to larger units: T-80 and T-88. Turbonetics isn't the only game in town; Precision has an older unit which is the PT-88 but still known around the boards for making big power. You could also move to the Garrett line with a G42-76 for 1000 horsepower or go larger with a big gun like the 88mm GT55. Again, these turbos are huge, especially the 47 and 55 models, lol. Like, literally, huge. For your truck, I am thinking you will need two smaller turbos; then again, I haven't seen under the hood of you truck. Have pictures? The last time a saw a SBC S-10 I saw two perfect places next to the trans, or there about, for two turbos.
4. Wastegate sizing goes like this: the more air you need to move around the turbine (not make boost), the larger of a wastegate you need. Of course, you must also consider whether you have restrictive headers, low-back pressure down-piping, restrictive turbine housing and wheel. For twins, I would use a 38-40mm wastegate. Depending upon which model you choose for a single, you will want a larger (60mm) wastegate. With regard to a blow-off valve, they all seem to be rather ubiquitous, simultaneously! I think the latest trend is choosing one that is the right color, the right shape, and or makes the most noise so people shutter in fear and empty the streets as your ride escalates you to super-stardom/super-macho. lol As with everything, some are garbage and price can be congruent to quality. Most all of the boost controllers perform well, some having specific features that some users require while others do not (e-boost 2, Innovative MSBC, I think the Apexi AVC is supposed to be useful, but don't take my word for it). Many times, the boost controller's reputation comes down to the guy setting it up knowing WTF he is doing or not. That seems to take precedence in a lot of end-user opinions on the internet.
5. When you tune the stock PCM for this, the MAF is no longer reading; it has reached peak capacity in the PCM. So, you basically tune the AFR through the PE tables and your wideband. Of course, this presents two problemos for us: with your fuel curve static, so must be your boost curve and atmospheric changes are not readily adapted to. In effect, you are stuck with the boost curve you setup and if you tune the car at 40*F at sea level, and then take the truck up into the hills on a warm day, you will run rich (and lean if vice versa). For a street car, this sucks —period. Some people will try to convince you otherwise, telling you they have nine-second cars on the PCM as they dazzle you with brilliance; this is a red-herring. Moderate boost on the stock PCM is not only a cobbled implement, it is very coarse in resolution. You have to increase the interval of your MAP axis to introduce the high MAP readings of the boost and this makes things coarse for a street vehicle. If you want to tweak your tune at the track, or the tuning atmosphere isn't much different than the track atmosphere (how often is that?), this is not really a big deal.
On turbos, you want a lower gear. I would use, at least, a 3.73 gear You can go even lower if you have short tires. What size tires are you using, anyway? The quicker you can load the engine, the quicker the turbo is going to come on-board. In a nutshell, turbos love load (something the bastard child belt driven supercharger could never do
).
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Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
(1) For the sake of calculations, let's assume you're running 117 mph now and you want to go 145 mph at 3400 lb. That means you're making about 420 hp right now. If you drop compression from 11.5 down to 8.5, you lose about 15% power, leaving you with 360 hp. At 145 mph, you'll need 800 hp. To get 800 hp when you start at 360, you'll need about 18 psi of intercooled boost assuming you're not reaching the limit of any system component.
(2) I'm using FelPro LTx head gaskets and ARP bolts. Been up to 25 psi without blowing them. I have blown head gaskets, but it was an over-boost incident.
(3) In order to reach 800 fwhp, the best overall combination turbo would probably be something like PT70GTQ with the .96 AR housing. However, you may consider using a PT76GTS .96, which is what I have. It'll spool a little slower, but will give you room to grow all the way up to 1100 or so hp. Plus the PT70GTQ may run into backpressure problems on 383 cid. You could always have Jose put together a PT70GTS and it would be the best of all worlds, but it would be a custom unit.
(4) I'm using a Tial 40 mm wastegate, but if I did it over I would use a JGS Precision 40 or even 50 mm.
(5) I'm using a stock ECM to make 900-1000 hp. Pulling 146 mph at 3750 lb. It's not optimal, but it works.
Mike
(2) I'm using FelPro LTx head gaskets and ARP bolts. Been up to 25 psi without blowing them. I have blown head gaskets, but it was an over-boost incident.
(3) In order to reach 800 fwhp, the best overall combination turbo would probably be something like PT70GTQ with the .96 AR housing. However, you may consider using a PT76GTS .96, which is what I have. It'll spool a little slower, but will give you room to grow all the way up to 1100 or so hp. Plus the PT70GTQ may run into backpressure problems on 383 cid. You could always have Jose put together a PT70GTS and it would be the best of all worlds, but it would be a custom unit.
(4) I'm using a Tial 40 mm wastegate, but if I did it over I would use a JGS Precision 40 or even 50 mm.
(5) I'm using a stock ECM to make 900-1000 hp. Pulling 146 mph at 3750 lb. It's not optimal, but it works.
Mike
Thread Starter
Registered User
Joined: Sep 2001
Posts: 212
From: Red Oak Tx
(1) For the sake of calculations, let's assume you're running 117 mph now and you want to go 145 mph at 3400 lb. That means you're making about 420 hp right now. If you drop compression from 11.5 down to 8.5, you lose about 15% power, leaving you with 360 hp. At 145 mph, you'll need 800 hp. To get 800 hp when you start at 360, you'll need about 18 psi of intercooled boost assuming you're not reaching the limit of any system component.
(2) I'm using FelPro LTx head gaskets and ARP bolts. Been up to 25 psi without blowing them. I have blown head gaskets, but it was an over-boost incident.
(3) In order to reach 800 fwhp, the best overall combination turbo would probably be something like PT70GTQ with the .96 AR housing. However, you may consider using a PT76GTS .96, which is what I have. It'll spool a little slower, but will give you room to grow all the way up to 1100 or so hp. Plus the PT70GTQ may run into backpressure problems on 383 cid. You could always have Jose put together a PT70GTS and it would be the best of all worlds, but it would be a custom unit.
(4) I'm using a Tial 40 mm wastegate, but if I did it over I would use a JGS Precision 40 or even 50 mm.
(5) I'm using a stock ECM to make 900-1000 hp. Pulling 146 mph at 3750 lb. It's not optimal, but it works.
Mike
(2) I'm using FelPro LTx head gaskets and ARP bolts. Been up to 25 psi without blowing them. I have blown head gaskets, but it was an over-boost incident.
(3) In order to reach 800 fwhp, the best overall combination turbo would probably be something like PT70GTQ with the .96 AR housing. However, you may consider using a PT76GTS .96, which is what I have. It'll spool a little slower, but will give you room to grow all the way up to 1100 or so hp. Plus the PT70GTQ may run into backpressure problems on 383 cid. You could always have Jose put together a PT70GTS and it would be the best of all worlds, but it would be a custom unit.
(4) I'm using a Tial 40 mm wastegate, but if I did it over I would use a JGS Precision 40 or even 50 mm.
(5) I'm using a stock ECM to make 900-1000 hp. Pulling 146 mph at 3750 lb. It's not optimal, but it works.
Mike
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Joined: Jun 2005
Posts: 626
From: MN
one thing not addressed yet I believe is the fact you have 11:1 compression generally that is a bit high for forced induction street driveable car. I think the most common for a turbo application is like 8:1 to 9.5:1 other than having the compression bit everything else that everyone said sounds good
Thread Starter
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Joined: Sep 2001
Posts: 212
From: Red Oak Tx
I need help understanding the sizing of the turbos and there effects.I can understand the size of the turbo,but how does the ar portion effect the operation of the turbo? if you had 2 t76 turbos and one has a .81 ar and the other had a .96 ar,how would that effect the performance? there are lots of turbo options that im finding and I need to know how to sort through them other than the hp rating that they are capable of.
I see some of the turbos are listed as t trim and s trim,what does this refer too.
I see some of the turbos are listed as t trim and s trim,what does this refer too.
Thread Starter
Registered User
Joined: Sep 2001
Posts: 212
From: Red Oak Tx
one thing not addressed yet I believe is the fact you have 11:1 compression generally that is a bit high for forced induction street driveable car. I think the most common for a turbo application is like 8:1 to 9.5:1 other than having the compression bit everything else that everyone said sounds good
I had planned on lowering compression ratio already.That was in my first post.
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Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
Registered User
Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
In order of importance for making power:
1. Compressor size
2. Turbine size
3. A/R
So, a small AR T91 will make significantly more power than a large AR T67. The T91 has a much larger turbine wheel too.
1. Compressor size
2. Turbine size
3. A/R
So, a small AR T91 will make significantly more power than a large AR T67. The T91 has a much larger turbine wheel too.
Thread Starter
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Joined: Sep 2001
Posts: 212
From: Red Oak Tx
Do i need to keep the rpms down with a turbo or is the sky the limit? with a 3.73 gear I should be able to go 145 at 6500 rpms and 150mph at 6700rpms and I can lock my yank 1:1 with the tc clutch.
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Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
Thread Starter
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Joined: Sep 2001
Posts: 212
From: Red Oak Tx
Last edited by slammed98gmc; Mar 19, 2007 at 07:43 PM.
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Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
The turbine side is more difficult, as there is no uniform sizing system. I can name some common ones from smallest to largest:
Small
P-trim
GTP
Q-trim
GTQ
GTS
GTR
F-trim
G-trim
Huge
You will need a minimum of a GTQ for those cubes. A GTS would be better. The F-trim and G-trim only come in the large-frame turbo's like the T91 and up.
By the way, I just noticed that they sell a PT70GTS, PT72GTS, PT74GTS, and a PT76GTS. If you don't want to jump all the way to the 76, you could get one of the others. However, I highly recommend the 76GTS.