I've got my waste gate block and the max that I've hit at WO is 27

 

Heck, mine's a 180hp pump with no work done to the stock fuel plate or even afc housing moved, just turned starwheel and the wastegate adjusted... can hit 32 psi...

 

Eric is pretty much right on. The 1 psi/10hp rule of thumb is only even remotely accurate within a narrow range that's very close to stock.

I've heard of 500hp being made with only 41psi.

I've also heard of 60psi FAILING to make 500hp.


There are MANY variables that will change the boost/hp equation.

Something else to remember-- the less boost it takes to make a certain HP, the more efficient the setup is.

Things like aftermarket cams, ported heads, larger turbine housings, etc can actually LOWER boost, but INCREASE hp.

Justin

 

Ok oK.. Man my behind is sore from that kickin...

That was a number that was thrown at me a long time ago. I agree from what i have seen it doesn't hold much water, but in this case where he has a stock unit with stock components and just the wastegate unhooked this should be close enough for his liking..

I too open the wastegate at 35 psi at around 1800 Rpm and I have the plate back from stock to save my clutch.

If you are making 60 psi boost, you don't have a stock charger either...

J-ow..errrr J-eh..

 

Why didnt Cummins just allow it to make 30+ pounds then? just a margin of safety for the I/C etc? So if I understand this, even if one was to increase fueling it would be a waste basically due to the waste gate opening at 19 or so and all you would do is make smoke. Also My 95 sounds different than my 93. I hear both spooling up but the 95 at one point makes a lower pitched groan or whine for a short time. Ive had cars with spent turbo bearings and it dosent sound like that, at least I dont think its a factor.

 

Well sorta. If you don't feed the wastegate actuator a boost signal it won't open till you can overcome the spring pressure. I am not sure of that value, but its high. When you get performance accessories you get the boost control elbow, which in basic terms limits the wastegate signal to open the gate at a preset pressure. You are right about smoke if you add fuel without more boost..

 

I don't think that the redline is 35. About 4 mechanics told me that the redline psi was 28. So when my wastegate blew out on my '94, I ordered a performance one for $86 and adjusted the wastegate to 26 psi. It didn't help but it will if I ever get a plate or get mine moved. Rather than the elbow, I would recommend a hooked up waste gate that is cranked to 26 psi.