STS Turbo Troubles

[WOT]

The biggest problem is that the T76 compressor is way too small. At 4.5 psi boost at 5200 rpm, the compressor is way off the map to the right in 45-50% efficiency range. When you try to overflow a turbo this way, it runs at super high rpm and produces very little boost. It ends up creating a bunch of backpressure in the exhaust and kills horsepower.

This also makes it hard to tune because of the crazy exhaust backpressure and reversion into the intake manifold during the intake and exhaust overlap period due to the high exhaust back pressure with little intake pressure.

Plus, the turbine side is too small as well. To make it even work at all they used a big A/R ratio which just makes the turbine side lazy at low rpm and since the turbine is too small, it tends to have boost control problems. To deal with this, they spec'd out dual waste gates.

The STS system could be make to work with a properly sized turbo or with twins, but not with a single T76. Acutally, if you look at the map closely, twin T76's with a smaller A/R ratio would be just about perfect...

 

[JTS VENOM PERFORMANCE]

Ok, so I'm the guy ronnie is trying to find help for.

I've decided to give up on the STS...eat the loss and try to save the motor for now. Basically what i have is a $20k budget to start in March of 2010. So i'm trying to get as much input as possible to make sure i get HP for the $$ spent this time arround.

In the mean time, i would like to try and get a little more power out of what i'm working with without risking a blown motor. March is a long time from now and i would really like to be able to play with my truck before then.

The intercooler came with the kit. It looks like it belongs on a Civic. I may pull it out.

When did STS quit selling these kits for the SRT-10 Rams?? They still advertise them and I ordered mine in March of this year.....and no, they are no help. They directed me to 3 tuners that all ran away when i told them my needs. (Even Hennesy wouldn't touch it) KRC / Marty was the only one willing to try and help. My tune shop(Extreame) used an SCT and e-mail tunes from Marty. I gave up on them when they started putting in tunes and skipping the dyno, telling me to road test and let them know. Real F-ing smart.

I went to thier competitor. They got a hold of Marty and retuned to make it drivable with mediocre HP and good, but not great, torque.

I was really expecting a lot closer to the published numbers for a $6000 kit, $2000 of extra parts for fuel and tuning and $2500 for the install and tuning. Add in an additional $1000 for the second shop and that's $11,500 or the $14000 spent. (ballance was on lowering kit, clutch kit, gauges ect..)

489 hp vs 557 published
557 tq vs 599 published

If i could get a solid 525 hp & 575 tq safely, i would be happy until spring.

Please, anyone making big numbers.....throw build suggestions at me so i can get ideas.

Goal - everyday driver @ 800 hp that all but bullet proof.

Can it be done for less then $20k and how?????

last note....i know why STS doesn't supply fuel & tunes for the SRT-10......SEE ABOVE!......(or, it can't be done safely while being cost effective!)

daily driver ,,,,800 reliable hp 20k...............no

 

[FlyingLow]

and thats it...just trying to do it right this time. went in looking for a ROE sc got talked into a STS...an expensive mistake...not looking to spend a pile of cash wrong again

Who talked you into an STS? Too bad you were not over here on this forum and asked sooner.

If you put in forged internals then you can turn up the boost and get a better tune on the STS. The initial problem with the STS was the fuel system and the overboost issue. The fuel issues was solved by replacing the 4 extra injectors with 10 larger injectors and then using either an SCT or VEC. The overboost is better controlled but it is not as stable as a supercharger because it is load dependent. A boost controller will greatly help.

When the boost is +/- 1 to 2 psi on a stock engine then failures happen during a spike. You don't want to go over 5 psi on a stock engine (7-8 with meth or an intercooler).

I also think you are running very rich especially with an intercooler. You could lean up some but you are not going to see large number. At 5 psi with the STS on a stock engine I got 478 RWHP and 620 TRQ. Later on I got it tuned by Sean Roe and got even less. But that was on a different dyno and different state.

You have a lot of money invested and it is up to you if you want to keep the STS. I blew my #3 last year and went with forged pistons. At 14 psi I'm at 778 RWP and 818 TRQ. I keep it around 10 PSI which gets me 660 RWHP and 720 TRQ. No matter what you decide at least get forged pistons. I would be happy to answer any questions you have. Just post up or PM. Welcome

Smoke

 

[razorbackfan]

Who talked you into an STS? Too bad you were not over here on this forum and asked sooner.

If you put in forged internals then you can turn up the boost and get a better tune on the STS. The initial problem with the STS was the fuel system and the overboost issue. The fuel issues was solved by replacing the 4 extra injectors with 10 larger injectors and then using either an SCT or VEC. The overboost is better controlled but it is not as stable as a supercharger because it is load dependent. A boost controller will greatly help.

When the boost is +/- 1 to 2 psi on a stock engine then failures happen during a spike. You don't want to go over 5 psi on a stock engine (7-8 with meth or an intercooler).

I also think you are running very rich especially with an intercooler. You could lean up some but you are not going to see large number. At 5 psi with the STS on a stock engine I got 478 RWHP and 620 TRQ. Later on I got it tuned by Sean Roe and got even less. But that was on a different dyno and different state.

You have a lot of money invested and it is up to you if you want to keep the STS. I blew my #3 last year and went with forged pistons. At 14 psi I'm at 778 RWP and 818 TRQ. I keep it around 10 PSI which gets me 660 RWHP and 720 TRQ. No matter what you decide at least get forged pistons. I would be happy to answer any questions you have. Just post up or PM. Welcome

Smoke

This is really good feedback on this system. I'm surprised that STS hasn't contacted you to find out how you made the system safe for this application instead of just abandoning it.

 

[mauiSRT/10]

Smoke is the only guy whom has survived with a STS. Its a real shame you didnt come to this site and do a search on STS. You would have never bought it. We have known for years how bad that system is. I will never forget how BigAsp lost 2 engines!!

Prof has said it so many times.....plan your work then work your plan. Build that plan with research first.

Good luck

patrick

 

[mauisrt10]

oops!was thinking of recomming a sts 4 somebody,maybe not now.saw it on some tv shows w/ great fanfare but maybe hype?location under truck didnt seem like a good idea on a toyota 4x4 !oh well.

 

[mauisrt10]

lets not confuse me w/ mauisrt/10 please!his photos are cool!website is nce.chose my name and no said some had a similer log in name.will change my login if he has a problem.still have ur truck ?lets talk &see how 2 go faster!aloha.

 

[FlyingLow]

The STS is a great system for other vehicles, just not the Viper.