So I am almost done with my 'build' (for now lol) and I just put in my Rtek 1.8. I was wondering if someone can give me a estimate RWHP with my set up. I am running a S4 13B (TII) extended street port (P/S, OMP, A/C & emissions delete, etc), stock S4 turbo (15 PSI), 720cc injectors (primary and secondary), walbro 255 with adjustable FPR, front mount IC, and full racing beat exhaust. If someone can guess what kind of HP im looking at I would greatly appreciate it! Feel free to give some suggestions and constructive criticism on the car.

 

stock S4 turbo @ 15psi. Soon your RWHP is going to be about 120.
You'll be making a lot of hot air and a broken turbo.

 

I know the turbo wont last long if I keep beating it but I was planning doing a huge turbo set up soon anyway. Do you really think I would run into a problem with my air being too hot with the front mount? I heard of these problems with the stock mount but I though Id be in the clear if I changed the intercooler set up.

 

Don't push a stock turbo past about 12 psi. You get so far outside the efficiency range of the turbo that all you're doing is superheating the air. There's no more power to be gained, but you'll increase IATs and risk of detonation. A stock turbo won't even hold that kind of boost for more than ~1000 RPM anyway.

 

ok ill take you guys advice! but I need help with lowering the boost...Its not being controlled by a boost controller. The previous owner did some kind of mod to the wastegate or something and made it reach these boost levels. Would you guys be able to tell me what could have been to do the turbo so it can be reversed (thats if reversing it is possible)..? thanks for the quick replies!

 

No modding is really needed to make it boost high, just the free flowing exhaust and intake. If they guy says he "modded it" perhaps he disabled the wastegate completely and now you're cooking it. Unless you start correctly modifying/fixing things, the only boost control you have is your foot. For now you should pull it off and port the wastegate.

 

Oh geez, it sounds like the previous owner disabled the wastegate. Besides the problem with the stock turbo puking its guts out after boosting over 14psi on a regular basis, at 43.5 psi rail pressure your fuel injectors are only good for about 310-335 bhp at the flywheel (about 260-285 RWHP), which your ported engine will easily exceed with a runaway turbo.

If the previous owner actually ran the turbo at 15psi then you may want to just send it to BNR for a full rebuild and have them fix the wastegate.
http://gonzaloherrero.com/bnr/index....d=67&Itemid=89

 

All this fuss about not running a stock turbo that high..

I ran stock turbo at 14-15psi for 3+ years, later upgraded to a BNR stage4
i still got it on the shelf, there is absolutely nothing wrong with that turbo..

My first BNR turbo has been fried already..

 

I ran mines at 14 psi for a year now after rebuilding it.

The thing is, its 14 psi through 2500-5000rpm, after 5krpm it drops to 8psi all the way to 8krpm because the turbo is just too small.

I can see it going badly if it was holding 14psi all the way to redline. But its only 14psi through the midrange. At 14 psi is is pushing the effeciency of the turbo, even at midrange rpm. Rotary engine sucks in a lot of air for such a small turbo.

 

I ran a stock s5 turbo @ 7-9psi (ported wastegate pressure) for 2 years w/o issure, I then upgraded to a v-mount IC but didn't have time to weld on the BOV flange. Within a couple weeks the CHRA started leaking oil. I then swapped out that turbo for another stock S5 unit and ran that @ 15+ psi (ebc) for over a year.

So in my experience compressor surge is far more dangerous than running the stock turbo outside its efficiency range in terms of damage to the turbo itself. HOWEVER intake temps past 12psi are stupid high, and I'm sure contributed to the death of my motor (along w/ agressive stock timing maps and "fuel economy" tune)

 

It doesnt seem like he disabled the waste gate though...the boost seems controlled and solid and the wastegate is still intact. Its still has spring pressure and the vac hoses connected to it. Now im confused! lol! Do you think ill drop some peak boost with the front mount installed? I get it in the mail today. Right now im running the stock mount...

 

Idk where i was at before my FMIC(didnt have the aftermarket guage in yet), but with my racingbeat revII system, corksport intake parts, rx7store front mount, and FCD i run 12-14psi. no issues. then again i rarely romp on this car

 

Yeah that's were I'm at now...I kind of don't like the idea of that little turd of a turbo pushing that much boost but like i said I didn't think I would run into to much of a problem with a front mount. But I would really appreciate it if someone can help me with my boost problem though. I'd like to be able to control my boost. Lol

 

if boost cannot be controlled i suggest putting the stock turbo intake pipe back on. It seems it was designed restrictive to help maintain boost.

 

Or add an exhaust restrictor. It's essentially a plate that looks like a metal exhaust gasket that has a smaller hole in the middle. You buy 2 gaskets (one for each side) and bolt it between 2 flanges. Instant boost creep killer.

 

i'm guessing about 45RWHP after the rear rotor dies.

 

im thing im just going to ride it out for now and do a smaller turbo set up this up coming month...

It already has one of these...lol im guessing thats one of the reasons my boost stays solid.

Does anyone one know what could have been done to the turbo to make it boost this way? Id really like to fix this so I can save for my original build (GT45 on E85). Help is much appreciated!

 

+1, i creeped to 12+ with a 34mm ported wastegate... restrictor plate with 1inch whole. back to 5 psi, and now i have manually raised to boost back to a safe and steady 10 psi, now it hits 10 instantly and stays there until past tq peak. much faster, and much safer.

 

Check that the wastegate actuator has a pressure source hooked up to it. If it's disconnected, the gate will not open and boost will go unchecked until the turbo's size/efficiency limitations force it to drop off.

If the actuator is connected properly, you're just boost creeping due to the micro 13mm S4 wastegate.

 

yeah its all connected so I guess its boost creep...lol but as for the HP question. Me and a buddy of mine did a friendly run. Long story short, his 7 is pulling 338 to the rear wheel with a similar set up and I pulled him about 3/4 car length so im going to guess 350ish??? im pretty happy with it to say the least!

 

On a stock S4 turbo you are maybe at 350RWHP? Man... I'd love to drive on THAT planet
Supposedly some have pushed 280. And that is a stretch, possibly with auxiliary injection and they weren't saying anything.

Long story short, you are not anywhere close to your friends 338RWHP. Then again he could be in la-la land as well.

 

Where can I find a restrictor plate? It I thought I had one on there but I dont lol.

Im not saying your wrong but I saw his dyno sheet. The only difference between our cars is hes running a slightly bigger than stock turbo and bigger injectors but on 12PSI and his motor only has a small port job. Im running extended street port stock turbo on 15PSI and 720's. We did a 3rd gear pull at about 55 on the highway and I pulled on him. Its the same exact cars so they weigh about the same. Would you be able to explain how I pulled him if he is making more power with the same car? the 350ish number was based on that Im not trying to claim anything as I havent dynoed the car but I just want to get an accurate estimate and thats all I have to go by...lol

 

Where did he get his 339HP number from? Your car IS NOT putting out over 300HP so unless there's something wrong with his car, it's not putting out 338HP.

 

if you pulled on him with a stock turbo, something is wrong with your friend setup there.

If you had 720 injectors all around, no way you are making over 300hp, especially on a rtek 1.8 since you cant adjust timing and fuel.
With the information you posted its making atleast 220-240rwhp depending on the health of the engine.

If you had some 1/4 mile times, it makes it a little bit easier to calculate horsepower. it wont be accurate but it would give a ballpark figure. Or you can go to a dyno.

 

Around 265rwhp on a dynojet is the best you could hope for with your setup.