24# of boost, stock compression and strait C16

[mulot30th]

Boost calculator spreadsheet tells me octane number should be okay?

same thing with 11.6# of boost, 9-1 compression pistons and 87 octane fuel supposedly do it?



can this be real?

 

[powderlites]

24 psi boost

Not in the real world, but thats my opinion.
Always make more power with proper low compression motor and right cam and Ign timming

 

[mulot30th]

At this point for my RX1 blower here is what happened:

Bone stock motor with stock compression, only cam timing done to it and running half C16 half pump fuel

12.7# of boost
dynoed right at 242hp


Then with 9-1 JE pistons, same cam timing, but this time pump fuel and a little c16.

11.6# of boost
dynoed right at 220hp


so doing the lower compression enabled me to run pump fuel BUT reduced the hp on dyno...

But I think a few hp were left on table because I ran too much octane. maybe 225hp...

 

[Boyko]

With 24# of boost your going heat up the intake charge real good depending on your turbo. Another problem is if you have the wrong turbine housing with a tight A/R you are going to see some big back pressure in your exhaust, you got to get the heat out of the cylinders or your next fuel charge is going to light to quick. I can not remember hearing anyone that ran that kind of compression with that much boost for reliability, you could probably do it with alcohol

 

[mulot30th]

C16 is 117 octane!

The turbo is a 2860RS which has a 0.60 A/R turbine housing.

 

[Boyko]

So are you talking about putting you stock pistons back in or do you have another sled? At 24# you are asking a lot out of that turbo, I don't think you will see a huge gain from 18 to 24#, but I have never tried it on a RX-1.

 

[mulot30th]

So are you talking about putting you stock pistons back in or do you have another sled? At 24# you are asking a lot out of that turbo, I don't think you will see a huge gain from 18 to 24#, but I have never tried it on a RX-1.

My turbo sled has always had stock engine.

gt2860rs is supposedly good for like 28psi.... according to boondocker...

 

[TWIN TURBO]

Boyko is right on in my opinion. A 28rs is only good for about 18 to 20 lbs efficiently. It may make higher numbers on the gauge but not much more HP for all the reasons above.

 

[efiguy]

It's true that a gt2860rs has been run up to 28psi, but you really need a bigger turbo to make boost efficiently if you're going to be running in that range. I don't know anyone who has run 24lbs reliably for very long with stock compression using race gas, but if you're careful you can make 15-18lbs work reliably with incredible response using stock compression and race gas, which seems to satisfy most people.

 

[HAMMER]

Would that be 18lbs at or near sea-level or at 10,000ft ??? You have 5 pounds less atmospheric pressure to work with at 10,000ft, and you would have to dramatically increase impeller speed to reach that same sea-level 18lbs, which would drive the compressor efficiency way down.

 

[efiguy]

You have about 4.6lbs less atmoshperic pressure at 10K' vs 0', you also have less exhuast backpressure, but the lesser air-density is a much bigger factor, making the turbo work harder at elevation. The GT28RS seems to still be efficient at 20lbs at elevation. We ride 8-10K ft. I personally wouldn't run much more than 16-17lbs with stock compression, customers have run as much as 20lbs, and I've seen what happens to pistons and rods when you have prolonged detonation so be careful.

 

[mulot30th]

I do run knock sensor that is placed almost right in my face.

I ride in the 2000-3000 ft range of elevation. At least, for now 18 psi seems reliable, I kept drag racing her without cooling between passes in april and except for the throttle bodies popping off problem, never had a hiccup.

 

[Remmy]

You are asking for problems running that much boost on a stock motor. If you aren't concerned with an expensive rebuild, more power to you. Otherwise do some preventative motor work.

CR

 

[mulot30th]

Even if I forge the motor, I will keep it high compression and run c16 into it for the better throttle response.

 

[Remmy]

I'm running JE 10:1s with the stock head gasket, which so far I'm pretty happy with, a little snappier than a head shim but more boost friendly at the same time.