Mike, pm'ing you my cell. Feel free to call me anytime if you want someone to bounce ideas off of....

 

"Yes Mike, the piping running from the turbo to the intercooler. Now as I'm looking at the picture, just trying to guesstimate, it looks to be either 2" or 2 1/4", because the T76 has a 3" outlet. This would definitely be too small for that turbo and that power level. If it's only 2", I would practically bet (if I had any money) that its' compressor surge we're seeing at 5900.

Also, put in the .063 restrictor. That's plenty of oil, and should stop the smoking. The .080 is way too big. FWIW, I always use a .058."

Like I care what you think and did :p just kidding. The inlet being too small and restricting makes sense and it is possible for the 5900 issue to be surge for sure. I will also see what size restrictors I have. I just want to be sure I get enough oil to the turbo. I almost think that oil smoke on decel is more engine mechanically related then oil at the turbo. I would think to large a restrictor would cause smoke at cruise and during higher RPM accel.

"Mike, pm'ing you my cell. Feel free to call me anytime if you want someone to bounce ideas off of...."

Be careful what you want for..... and thanks. talk to you soon.

Mike Norris

 

Hey Mike, haven't seen this mentioned and it's kinda basic but since things are being tossed out all over, what type of dyno is it?

I'm an indie guy and the shop that I tune from uses a DJ224 w/o LC and I can't get any decent spooling out of STS setups on it. They seem to do ok on the 248s though even w/o any load option. The few I have tuned have had to be on the street. Even then, the M6s don't want to make much boost in first, and don't spool like they 'should' in second either.

 

So I see you're still a funny guy. And in more ways than one.

Oil smoke on decel is from too large of a restrictor. I understand your line of thinking (I think), but for whatever reason, that's how it works. I had the same problem and just kept decreasing the restrictor size until it cleared up.

Don't quote me, but I believe Corky Bell says you you only need .048 for more than adequate oiling. (but you probably don't care what he thinks either )

 

Rob Raymer back on tech. WOW~!

 

Yeah, the restrictor's the prob for that. The guy in the red C6 ZO6 behind me today was all pissed off about it I'm thinking. He disappeared for a bit...(he was fading away anyhow).

Good times...I guess 550/550 isn't all bad.


Mike, also, the damn horn started honking randomly...never did that before...LOL

Honked right at an Oakland cop today without touching the wheel!

 

The most power my car has ever made on a dyno was 530 SAE on 17psi with a blown up turbine wheel (Spooled really slow). Never got to the track on the .96 a/r before the turbine wheel came apart. I think it had high 9's @ high 130's in it but I'll never know for sure. If you believe in dyno numbers, I went 10.5 @ 130mph with 470 uncorrected HP and 3850lbs. Mr Watt would be spinning in his grave if that is the case. Just proves that dynos really do give in accurate numbers. MPH at the track tells the real story.

Every spoolup/power issue I have had has been related to either a leak or excessive back pressure. Measure your drive pressure to get an idea on what is going on. I found the choke limit on the .81 a/r housing and R turbine wheel happened around the 130mph range for my car (3850lb race weight). I could trap 130mph with 14psi. Took another 4 psi to get the car into the 133-134 range. After swapping to the .96 a/r housing I gained 800-1000 rpms of power band (depending on boost level) and was shifting the car at 6800 vs 6000. Made a huge difference since it was against the converter over 6000rpms. Biggest complaint on my car was it spooled too fast on the street which made it hard to drive. Lowering street boost down to 12psi and setting up the controller to create some lag really helped with that. Full boost in 1st gear was never a problem even without traction.

On the transbrake or foot brake I can build 5 psi in about 1.5 seconds and 20psi in just under 3 seconds (using the transbrake for 20psi of course). Hardest part about building boost is getting that first 5psi, after that it snowballs.

My 10.1 pass is also into a 20mph head wind, probably could have gone 9's if I had skinnies vs stock SS wheels/tires, but that's life. A stock f-body is lucky to trap as high as 100mph at my location as well during most of the year to give you a reference point.

 

Frost, it was on a Dynojet 248. Now that I think of it I tuned an STS GTO quite some time ago and will have to compare those curves and see what they look like. Pretty sure it was a mostly stock engine and base STS.

I know I am funny but looks are not everything. Thanks for the restrictor and all other info and you are right in what I was thinking. We will see what it needs. The next couple days will be a zoo getting ready to head to Sebring for thursday and Friday and the Gainesvill for saturday and Sunday, but I will try to get a call to you soon.

Ronnie, 550/550 is nothing to laugh at and a great street power range to say the least. Dumbfounded by the horn for sure.

Zombie, thanks for posting and if you have the the dyno graph to post it would be great. I do not really care about the numbers but more the curve up to 5000 RPM and where peak boost was hit.

By the way I do understand that if I was suing a load dyno that it would spool faster and it most likely does spool a little faster on the street. But when comparing this setup to a conventional front mount on my dyno it still takes almost twice as long to make boost.

Here is something I thought of today. Lets say you take the setup in geeteego's GTO in that is should be a pretty healthy NA engine at 425 RWHP and 425 RWT. You could have a nice 1 7/8" header into 3' pipes into a 3.5" Y to the turbo and also had a 3-3.5" piping for the pressure side. If that would allow the engine to make 100 or more RWT from 2000-4500 RPM then what it is making now, would it not be stronger down low even though there would be still a slow spooling issue. Then at just 8 PSI you could make 625-650-ish RWHP and at 10 PSI you could make 675-700-ish RWHP. A lot less boost pressure on the engine to make more power. I do know that there would still be a lag as far as boost is concerned, but the extra 100-150(?) RWT down low would make up for the lack of boost. I could also theoretically wrap the complete exhaust from collector to turbo. I say theoretically because I know it would take a lot of convincing for me to do that. But does what I am thinking make sense at all? Let me know if this logic plays out.

Thanks again all.

Mike Norris

 

Unfortunately that logic does not play out. The turbine housing would still be the major choke point in the exhaust system, completely negating any of the benefits of the expensive headers and larger pipe. The resulting backpressure will kill any chance the headers had at exhaust scavenging before you even see any real boost. After the boost starts, your intake/exhaust pressure ratio will only get worse since you now have much less heat and velocity, leaving only pressure to drive the turbo. This same logic is why log manifolds or stock manifolds work surprisingly well in front mount turbos.

 

Going bigger on the exhaust/headers before the turbo will only make the lag worse due to the amount of surface area it has, been there done that got the t-shirt. I went to 2.5" piping all the way from the manifolds to the turbo (20% less surface area vs 3"). I also wrapped it and still have another 5' of piping that needs to be wrapped. It made a HUGE difference and I had been using the stock exhaust. I don't know if Geeteego has his exhaust wrapped, but if not, it is the very next mod that needs to be done. I'd even consider double wrapping it. Another thing that I gained a lot of power from was going from a 3" after turbo exhaust to a 4" exhaust. My turbo used a 3.5" v-band was and choking very bad due to the way the exhaust was made and it was a max of 3' long of 3" ID piping. I now have a 3.5"-4" transition and it made a large difference as well. Easy way to check that for free is just pull the exhaust off and see if it makes a difference. If it's better, then a new setup is needed.

This is the old .81 housing that has zero top end. You can see me go against the transbrake and then spool it. I was sitting at about 6" vac until I got on the trans brake. 7-8psi on that launch. My converter is the absolute tightest 9.5" converter Vigilante makes. Stalls 3k N/a on the trans brake.

http://www.youtube.com/watch?v=Ixi0vMsAQS8

Just saw the car is an M6... going to an auto will make the car spool much much faster. I don't think i'd ever want a stick shift turbo car again after experience the awesomness of turbo + auto.

 

All:

Again, I am overwhelmed and extremely thankful for the responses. So it's leave the exhaust as it is from the manifold-turbo (including the 2" driver crossover into the I pipe) and investigate the 3"x16" after turbo piping? Also leave the pressure side as it sits?

The car definitely feels strong on the street, just not strong like it should be. Going auto is not in the cards...I just like rowing too much, and I'm rarely at the track anyways.

 

gametech, thanks for the buzzkill but the way folks are talking it seemed that would be the response.

Thanks again Zombie and as Ronnie mentioned, go to an auto at this point most likely is not an option for him. I can see an auto helping at the track to use a trans brake to build boost. We are talking a daily driver street car here.

Ronnie, after the preliminary testing (NA dyno, compression test, check valve springs, check pushrod preload, check cam timing) is done it seems a 4" exhaust after the turbo as well as 3" from the compressor housing to the intercooler is what we need to look at now. It just kills me to run that much boost to make 650-750 RWHP. Heck, I have had Procharger cars making 10-12 PSI make that kind of power with better low end.

Talk to you soon and thanks again to everyone.

Mike Norris

 

I don't feel going to a 3" pipe from turbo to IC is going to help out much. I'm running 2.5" and able to make decent power. If you guys are only looking for 650-700 rwhp I would strongly suggest swapping the .96 a/r for a .81 a/r housing. It will make a very big difference in how it spools and should not be much of a choke issue.

It's very odd that you guys are getting that drop at high rpms. You say the drop only happens at higher boost, that leads me to believe that you are hitting higher boost at that point and the BOV starts leaking. I've had several BOV issues myself in the past that created all sorts of odd lag and boost problems. I think it would be worth while to look closer at it, even eliminate it from the system all together to check how it performs. If the gasket sealing it to the pipe is good (tials use an o-ring i've seen go bad many times) hook up an air compressor with 20psi to hold the gate shut and re-dyno.

 

Zombie, thanks for the input.

To give you a perspective, I like to run my car the way Les (Loboost) out your way runs. He has the gray GTO with the APS twins at some insane rwhp#. He's usually out playing with sportbikes and turbo Vipers.

Meaning: lots of 3rd, 4th, 5th gear pulls and very little in the way of dig racing. That's why I wanted the .96AR.

As said, that car is making more power on the street, for sure, under a load. I also worry that the excessive oiling is contributing to the problem by placing undue pressure on the seals or creeping past them, possibly causing a high-psi stumble.

So, I'll just take it easy until we can get further into it.

Again, thanks Mike and everyone else for the help. It's been a very long, very rough, and very expensive journey for this little GTO. This should be required reading for all the folks who try and build a FI car with the lowest common denominator being dollars spent. It never ends up cheap.

 

Sorry guys but I actually had a bunch to do yesterday and never got to a PC.

"I don't feel going to a 3" pipe from turbo to IC is going to help out much. I'm running 2.5" and able to make decent power. If you guys are only looking for 650-700 rwhp I would strongly suggest swapping the .96 a/r for a .81 a/r housing. It will make a very big difference in how it spools and should not be much of a choke issue.

It's very odd that you guys are getting that drop at high rpms. You say the drop only happens at higher boost, that leads me to believe that you are hitting higher boost at that point and the BOV starts leaking. I've had several BOV issues myself in the past that created all sorts of odd lag and boost problems. I think it would be worth while to look closer at it, even eliminate it from the system all together to check how it performs. If the gasket sealing it to the pipe is good (tials use an o-ring i've seen go bad many times) hook up an air compressor with 20psi to hold the gate shut and re-dyno."

Makes sense I think. On the miss and BOV, the boost does not drop and the A/F stays consistant. I would expect to boost to drop suddenly and the A/F to go pretty rich. PE and VE tables are nice in smooth. Just feels like a misfire.

I did come across an older dyno graph that I had mentioned I recalled from an STS GTO and you "header haters" may be surprised I will give more details once I can post the praph and mods done to the car. Just confuses things more.

Thanks again.

Mike Norris

 

Here is the dyno sheet I was talking about. 2004 GTO M6, TR 224 114, Stg 3 5.3 Heads, Stainless Works longtubes, 2.5" OR pipes, Base STS non-intercooled. before the STS she put down 385 RWHP and 376 RWT.

I do not remember the specifics as it was more then 3 years ago. I want to say it was the base turbo and the SW piping was adapted to fit to the turbo as easily as possible. Maybe making 6-7 PSI. I had very little timing due to the IAT's and the fuel system was giving out on top.

Graph looks to have full boost by 3500-ish or so and nice torque curve as compared to the lagginess of Ronnie's setup. What I am getting at is that a header package seems to work here against what everyone says. Is it becasue it is a smaller turbo and no intercooler? Would it run out of steam at 550 RWHP? Things to think about.

Mike Norris

 

This is a little different thinking, but something to consider.

Are you able to get any pressure data from the exhaust? Between the motor, and the turbo. You can get into an issue that I see commonly on diesel motors, where you increase the "boost" but the exhaust backpressure increases more than the boost, so you get a net 0 gain, or a loss in power, even through your pumping more air/boost into the motor.

I would not be suprised if your seeing 22-30 psi of back pressure in the exhaust, and that will kill power numbers compared to what that car will make NA with good exhaust.

Also running the car on a loaded dyno (mustang or superflow) with road simulation might help spool as well, I have seen several times, that boost on diesel applications are not what they are on the street on 248 dynos. You might be running into the same issue with the STS kit.

I hope this helps.

Ryan

 

Ryan, you are pretty much stating what is happening in that the STS setup with stock manifolds and its small piping does nothing to make there any benefit to a higher HP engine. By higher HP I mean better heads, better intake, bigger cam and so on. It seems like pretty much a stock cube engine with a smaller blower cam (216/224 116??), stock heads, stock intake manifold but with forged pistons, forged rods and either a stock or forged crank would be best.

Looking at the older dyno from another car I posted I can picture that with about 10-12 PSI, an efficient intercooler and meth would be able to do 550 RWHP and 550 RWT if the smaller turbo will push that much. Maybe 600-600 but probably not.

Thanks again.

Mike Norris

 

was that Ians car?

 

I also have an 04 GTO with T-76 but IM playing with a stock bottom end. When I first switched to the 76 it also had the .96 AR housing and wouldn't spool till 4500. Once I switched to .81 housing I discoverd the boost or the 7 lbs I run. IT makes a huge difference going from a .96 to a .81.

Mike P