Zero R

iTrader: (1)

If you use the guru kits you will have sealing issues unless you go out of your way to insure you don't, hence all the big pics. I had one customer bring them in years ago after that I wouldn't use them anymore. Get the proper hardware and you wont need chamfered holes and stacked o-rings and washers. I would have a concern with centre line bore, on the 13B's not so much you can be sloppy some and believe me seeing some people doing it on drill presses proves it though those procedures insure cracked plates eventually. On the 20B's it is important however, my guess is from the simple info here goopy is trying to get around this issue by simply only studding part of the block rather than dealing with proper machining headaches. If done right it should work. I do have a slight concern on what he means by "making contact" however. I bet dollars to donuts Guru will sell you stud kits all day long for 20B's however I bet they wont build 20B's without other "necessary" items to insure certain concerns are resolved.

~S~

thewird

iTrader: (8)

My current target on this project is a GTX4202R with a 1.0 Tial housing (thanks to Sean) with most likely a large streetport (not set in stone yet).

I noticed Garrett is offering a GTX4502R now (probably not new but I just noticed it today). It's basically a GTX4202R with a 45R turbine. Anyone have any thoughts on this turbo for a track car?

thewird

thewird

iTrader: (8)

Figured I'd bump up this thread to avoid starting a new one and updating some concerns about the motor.

The motor has been running well with already 5 track days under its belt. The Goopy studding has not caused any issues and the motor does not leak as so many said it would. Motor sees pretty consistent water temps in the 230-240*F range with 8,000 RPM as a shift point and the occassional 8,500 RPM rev limiter too . I'm working on the cooling to improve that but its been running well. The only real issue I've been having is breaking transmissions. Already broke 2, 3rd gear every time. Currently having Liberty Gears build me a transmission to hopefully take the power.

Anyway, what are your thoughts on the drop-off in power on this dyno graph? My ports are huge so its a high revving motor but the power wall is bugging me. I think the Tial 1.0 A/R is causing the motor to fall on its face at 8,000 RPM. It seems like it should keep making more power. The wavy torque curve is from rich spots at the time of the pull that I later fixed. Or maybe its my bored out FD FEED throttle body is a restriction too? I think the fact that peak torque is below 6,000 RPM is also a sign of some restriction going on because that doesn't make sense for the porting hehe.

I'll probably get a Tial 1.15 A/R turbine housing once I know the transmission can take more power to test.



Oh, and here is a log of my Exhaust Manifold Pressure Sensor during that same dyno pull... (There may have been a very small exhaust leak starting to form at the time of the pull). This sensor actually works quite well. When I had the Apexi ATS silencer in the exhaust to try to limit the power some, manifold pressure was around 40 psi and then dropped to what you see in the picture now after I removed it.



thewird

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It won't be the t/body. A 20B can make well over 1000hp with a bored FD t/body.
I suspect it's the turbine housing. What boost are you running? If the turbine back pressure is more than a few psi above intake pressure there is a restriction. I run a BWS475 on a street port 13B and changed from a 1.10 housing to a 1.25 and found the turbo spooled just as quick and made more hp. There was only about 2 psi difference in back pressure between the 2 housings but obviously the engine wanted the extra flow of the larger housing. It's a TII engine and intake and hp hangs on until about 9000rpm. You're not losing boost at the top end are you?

PDF

What size exhaust do you have? Is the w/gate piped back into the exhaust?

Do you have 2mm or 3mm seals? (actually I think you wrote Als somewhere so they will be 2mm)

Running out of ignition power/coil saturation time at higher rpm?

Are you adding a reasonable amount of ignition timing after peak torque?

You could always up the boost after 7000rpm

thewird

iTrader: (8)

Full 4" all the way to the back, yes the wastegate is piped back into the exhaust.

2mm Goopy seals.

Don't think so. Running AEM coils with 4.5ms dwell.

Yes.

Currently the car is running on wastegate only. It makes about 16 PSI up to 6,000 RPM and then drops to 13.5 PSI by 7,500 RPM. This is with 12 pound spring in a Tial 60mm wastegate.

thewird

PDF

My money is on the turbine then. Besides, it's the easiest item to change. Try the 1.15 Tial.
If your turbine back pressure readings are accurate it means back pressure is roughly 10psi more than your 13.5psi boost pressure at 7500rpm. Mine was only 3psi higher then boost pressure when I decided to change the turbine housing.

Some sort of boost control would possibly help matters too, so that you can ramp boost at higher rpm, rather than lose it. Remember, the more boost your run, the higher the engines VE - much like increasing port timing in an NA engine.

The other point to consider is the GT4202 comp wheel is not hugely efficient at 13.5psi. It may be that a combination of low boost, large ports, and 3 rotors means that at 8000rpm wheel flow is too far to the right of the compressor map. Increasing boost moves the wheel closer to it's peak efficiency, and therefore more total flow.

thewird

iTrader: (8)

WOW, I never realized how close a compressor map calculation could be. You are absolutely right, I am peaking the compressor map @ 13 PSI (0.9 bar). The engine is sucking it dry

Compressor map is below as a reference...

At 7,800 RPM which is my peak power of 646 rwhp and boost is 13 PSI by that point and holds to pretty much redline (8,700 RPM). With 1.9 bar absolute (13 PSI/0.9 bar), according to the compressor map 84-85 lbs/min of air is the max the turbo can flow. This translates to roughly 840-850 piston rwhp. Convert to rotary HP by dividing by 1.3 and we get 646-653 rotary rwhp which is pretty damn close to my peak HP. I could have squeezed a few more ponies by leaning out the mixture up top, it was only around 11.0-11.1 AFR which is rich for the boost. Don't you love it when theory matches reality

If this is true, I wonder if changing the turbine housing would even help. Although my exhaust manifold pressures do suggest there is too much backpressure there. Probably change turbine housing anyway before hooking up the boost controller to test and know for sure.



thewird

afawaterpolo

iTrader: (7)

I was wondering if you ever got around to changing the turbine housing to the 1.15 and seeing if that helped at all? You have some really nice numbers there.

thewird

iTrader: (8)

Didn't get around to it since I didn't need more power but I'm gonna change it over the winter for sure.

thewird

carx7

iTrader: (31)

I didn't re-read the entire thread, but did you say what size W/G you are running?

Years ago (12?)I built a manifold/turbo setup that I found performed very well on my 13b and I will be applying similar theories to my 20b turbo/manifold.

The theory was to using a high flowing turbine wheel (GTQ at the time) and a small exhaust housing (.84 on my 13b with a 4" exhaust) to minimize spool time. Then, when restriction of the exhaust became and issue, I used twin 38mm W/Gs to bleed exhaust energy and reduce turbine manifold pressure. The result was 19psi by 3900RPM in 3rd gear and peak power of 470RWHP on pump fuel.