Considering switching from .91 hoising to 1.0?

[monster50iii]

I hit the dyno recently, and hit 655hp and 1171tq on a conservative tune. I'm happy for the most part where I stopped. My issue is I drop 100hp roughly from 2850rpms to 3700rpms. My fueling stays constant which makes me believe my turbine is choking the engine. My charger is a 64.5/.91/73 sxe. Do I have enough compressor to swap to the 1.0 hpusing and free up some top end power? Even a 500hp tune dips off pretty good above 3000rpms.

 

[Bdsankey]

What is your drive pressure in the RPM area you're noticing a power drop?

 

[monster50iii]

I dont have a gauge to monitor that.. that would definitely be good info to have.

 

[Bdsankey]

I would check that first before swapping housings. I would guess you're likely running into an airflow problem but it's better to be sure instead of throwing parts at something.

 

[D_Ferrante801]

What does EGT do during that area?

is boost tapering off during this time? Rail pressure holding steady? TQ values staying flat and following?

 

[monster50iii]

I have a tool coming so I can test for boost leaks. I've seen my max boost be at 42psi around 2800, and as rpms pick up watch it drop to nearly 32psi. I bought a tool that I can hopefully safely test my system to 40psi. I suspect my oring at the stupid plastic elbow on the cold side off the intercooler may be the culprit. We will see..

Rp held great, and it carried commanded pulse the entire pull. Egts get warm, right around 1600. At 3400 I'm commanding 2300us and only 21deg timing. I'm sure more timing would help some but I want this thing to live lol.

I'm already on the boost dealio. But I couldn't help but ponder about the exhaust housing.


Thanks for the replys!

 

[gmduramax]

Valve springs I don’t see why you would lose boost

 

[monster50iii]

I ordered a 1.0 housing.. I may also have it machine for a 66 wheel this fall/winter. I'll probably get to the dyno again after the housing swap to see what the gains are.

 

[monster50iii]

Swapped housings; I did one pull tonight and egts got to 1427*. Before I would see nearly 1600*. Next is dyno time at some point!

 

[rcr1978]

Bumping this up since the turbo's for sale now, just curious did you figure out if you thought it was the turbine side holding you back or the compressor side? How much driveabilty did you loose with the 1.0 housing, also what are you going to try next? I'm considering a 64.5 but with the smaller 76/68 turbine with a .83 T4 gated housing for my twin setup, probably really no relevance to what your doing but just interested.

 

[Bdsankey]

Bumping this up since the turbo's for sale now, just curious did you figure out if you thought it was the turbine side holding you back or the compressor side? How much driveabilty did you loose with the 1.0 housing, also what are you going to try next? I'm considering a 64.5 but with the smaller 76/68 turbine with a .83 T4 gated housing for my twin setup, probably really no relevance to what your doing but just interested.

My only concern with the .83 would be the loss of overall flow/where it chokes out and the added cost over say the standard 0.91 housing. I am going 364.5/68/0.91 and 480/96/1.15 on my LB7 after going back and forth with a few guys who have ran that setup or a very very similar setup as I also thought about going with the tight gated housing on either turbine wheel.

 

[monster50iii]

So I put the 1.0 housing on the 64.5, and besides losing 5-8psi of drive pressure nothing else really changed. Spool was a hair slower, but nothing major by any means. I now have an s369 on it. Im still ironing out timing and shift points, but it does alot better than I expected. I kept the .91 housing on the 69. It even tows pretty dang well also, not as good as the 64.5 of course, but it does ok.

An interesting note, the 69 makes about 3-5psi more boost than drive pressure at 15psi of boost.

 

[rcr1978]

My only concern with the .83 would be the loss of overall flow/where it chokes out and the added cost over say the standard 0.91 housing. I am going 364.5/68/0.91 and 480/96/1.15 on my LB7 after going back and forth with a few guys who have ran that setup or a very very similar setup as I also thought about going with the tight gated housing on either turbine wheel.

I'll reply in your towing twins thread so I don't mess this one up to bad.