Your Opinions...Is a 38mm WG Too Small for 350-400whp?

[240hoke]

I think runnign a seperate pipe is a little extreme although it would be pretty cool. THe wg pipe is only dumping exhaust when at full boost obviously so the exhaust smell isnt that bad, I havent noticed it to much. The noise is what gets ya, Ive enjoyed having mine open for a while but Im about so plumb it back in

[BLOZ UP]

I used a 38mm TiAL on my 390hp/440tq VG30ET without any problems.

[jgkurz]

Ok, here's an interesting one. The below graphs are from my 3.0L L28ET with a under-sized internally wastegated T4/T3. I had the internal wastegate hole drilled out to around 1 3/16". I then fabricated a stainless steel lawn mower valve as a larger flapper door. Lastly, I changed out the actuator to an adjustable billet unit from Forge Motorsport.

 

http://www.forgemotorsport.com/content.asp?inc=product&cat=0001&product=FMAC048

 

My electronic boost controller is a Biltz dual solenoid model with the boost sensitivity set at only 10%.

 

My problem has not been boost creep but boost bleed. I have run as high as 25psi at the onset of boost and it bleeds down to about 17 psi at the higher RPM's. My guess is that my pre-turbine pressure grows as the engine climbs in RPM thus pushing the wastegate door open instead of going through the turbine. Boost stability is relatively flat at 13PSI or lower.

 

To solve this I really need a new turbo, turbo header and a properly sized external wastegate.

 

 

 

310 RWHP with a max of 12.5 PSI

 

373RWHP with a max of 21.4PSI

[JustinOlson]

I'd say its not the lack of the wastegate being too small, or big but the turbo is just out of capacity. Maybe try running with an open downpipe and logging some boost. I bet that would flatten out the boost curve if the turbo has anything left in it.

 

Regards,

Justin

[jgkurz]

I'd say its not the lack of the wastegate being too small, or big but the turbo is just out of capacity. Maybe try running with an open downpipe and logging some boost. I bet that would flatten out the boost curve if the turbo has anything left in it.

 

Justin, You may be on to something My turbo was built by the now "out of business" Innovative Turbo. Below are the specs that I'm aware of. My recent dyno run's showed that between 4600RPM and 5600RPM my HP was almost completely flat at 370RWHP. It's like it got to 4600 and just stopped building power. I'd like to go to a GT35R but that will take some major re-work of my downpipe, exhaust manifold and intercooler tubing. My guess is that the compressor side in my current turbo is too small. If I could determine that I for sure don't have turbine back pressure I would probably have my compressor side changed to a simple 60-1 instead of the crap I have now. That way I could make an improvement without any major fabrication. My original goal, like Yasin, was 400RWHP of which I'm a little short. If I could make more than 17psi at the higher RPM's I might make it. I would guess that my head and exhaust system could also be improved. I think I need to have BRAAP do a head for me...... Getting to the next stage in power is going to be VERY expensive.

 

Compressor housing:

T04E .50 A/R with 3" inlet (Kind of small but allows no spacer to clear exhaust manifold)

 

Compressor wheel:

Custom Innovative wheel that supposedly supports 60lb/min

 

CHRA:

360 degree bearing, water cooled with big shaft

 

Turbine housing:

OEM Nissan .63 A/R with machined 2.5" outlet

 

Turbine wheel:

T3 stage V 10 blade

 

 

 

Yasin, Sorry for the hijack. I hope this is helpful info.

[JustinOlson]

Its hard to tell, but I would focus on the turbo side of things before dropping money on the head right now. If your turbo is maxed out, your only going to make the same power at less boost with a new head. I would try and get away from the Nissan turbine housing and internal gate if you are looking at making more power. I'm taking welding classes right now and will have a very nice tig setup soon. This winter sometime I'd love to help you redo your turbo system on your car. 3" downpipe, Nice exhaust manifold with external wastegate and bigger turbo. I bet 500whp would happen if we hit the restrictions in your setup.

 

btw, here are some welds I layed down about a week ago:

 

Regards,

Justin