I run the combo in my sig with a precision .63 exhaust housing on the turbo. I'm looking to see where I can pickup some power without opening up the untouched longblock if possible. My car is set at 27psi with 23/21 timing on alcohol and runs very strong but of course who isn't looking for more power :tongue: Revving only to 5200ish with a stock longblock, is there any real world gain to be made with a .82 exhaust housing? 95 percent of people on this board run the .63 housing and searching yields next to nothing as far as actual comparisions between the different housings.
.63 vs .82
- Thread starter LOLGN
- Start date
Bison, if you'd seen it this is Kash's car that was a gnx replica in the making with 43k miles on it. I have comp 980's on it and it pulls strongly up top. The converter in the car is really a bit too loose, there is no traction in 1st gear and sometimes into 2nd as well. It was much easier to drive with the stock d5 in it. I have a transbrake in the car and can build as much boost as I'd like very quickly, and street driving it spools up nicely as well.
- Joined
- May 27, 2001
A transbrake doesnt mean anything if the engine cant get the turbo spooled up. I dont think a 2800 is enough for that much turbo with a .82 on it.
Transbrakes are a chicken/egg situation when it comes to boost. If the engine won't make enough RPMs to get the turbo to start making boost, the engine is just going to plateau while you have it on the brake.
Transbrakes are a chicken/egg situation when it comes to boost. If the engine won't make enough RPMs to get the turbo to start making boost, the engine is just going to plateau while you have it on the brake.
heres a snippet from a tech article i was reading not sure if this will help any
Imagine two 3.5L engines both using GT30R turbochargers. The only difference between the two engines is a different turbine housing A/R; otherwise the two engines are identical:
1. Engine #1 has turbine housing with an A/R of 0.63
2. Engine #2 has a turbine housing with an A/R of 1.06.
What can we infer about the intended use and the turbocharger matching for each engine?
Engine#1: This engine is using a smaller A/R turbine housing (0.63) thus biased more towards low-end torque and optimal boost response. Many would describe this as being more "fun" to drive on the street, as normal daily driving habits tend to favor transient response. However, at higher engine speeds, this smaller A/R housing will result in high backpressure, which can result in a loss of top end power. This type of engine performance is desirable for street applications where the low speed boost response and transient conditions are more important than top end power.
Engine #2: This engine is using a larger A/R turbine housing (1.06) and is biased towards peak horsepower, while sacrificing transient response and torque at very low engine speeds. The larger A/R turbine housing will continue to minimize backpressure at high rpm, to the benefit of engine peak power. On the other hand, this will also raise the engine speed at which the turbo can provide boost, increasing time to boost. The performance of Engine #2 is more desirable for racing applications than Engine #1 since Engine #2 will be operating at high engine speeds most of the time.
by the way this is the article turbo_tech102
Imagine two 3.5L engines both using GT30R turbochargers. The only difference between the two engines is a different turbine housing A/R; otherwise the two engines are identical:
1. Engine #1 has turbine housing with an A/R of 0.63
2. Engine #2 has a turbine housing with an A/R of 1.06.
What can we infer about the intended use and the turbocharger matching for each engine?
Engine#1: This engine is using a smaller A/R turbine housing (0.63) thus biased more towards low-end torque and optimal boost response. Many would describe this as being more "fun" to drive on the street, as normal daily driving habits tend to favor transient response. However, at higher engine speeds, this smaller A/R housing will result in high backpressure, which can result in a loss of top end power. This type of engine performance is desirable for street applications where the low speed boost response and transient conditions are more important than top end power.
Engine #2: This engine is using a larger A/R turbine housing (1.06) and is biased towards peak horsepower, while sacrificing transient response and torque at very low engine speeds. The larger A/R turbine housing will continue to minimize backpressure at high rpm, to the benefit of engine peak power. On the other hand, this will also raise the engine speed at which the turbo can provide boost, increasing time to boost. The performance of Engine #2 is more desirable for racing applications than Engine #1 since Engine #2 will be operating at high engine speeds most of the time.
by the way this is the article turbo_tech102
Im familiar with the car. Its the best example of a GNX replica out there imo. Ive been in it on a few occasions. You can see me in it on one of Febus's videos. If you have a PTC 10" 2800 it may be enough for the .82 but as Jay said it might hurt it a little down low.
I just got a .82 for my 6152. Down low the car is incredible, consistant 60 foots in the mid 1.5's the last few times to the track with the .63 housing. The car has no nuts up top though. I figured the housing is an easy enough mod that I can swap it on and she how it does. I have the Trans out now and I was thinking of having Dusty tighten my 2800 to a 2400, but I figure I would try this first. Heck i can always change it back real easy. Besides it might be fun to go out and roll race some of these kids since thats all they seem to know how to do anyways!
Buttonfly that's kind of how my car feels, it leaves very very strongly on the rare occasion that it hooks in first gear and comparatively feels weak up top. I think it's worth experimenting with the larger housing to soften the hit down low a bit and improve the performance once under way. There's just very little out there in terms of back to back testing or any kind of hard data.
Well for starters you need to go to the track and get some hardcore data. Get a 60ft, get a 1/8 et & mph, get a 1/4 et and mph, see what rpm you are at 0 boost, what rpm drop between shifts, what rpm you are crossing the line at. Then you can see exactly what your car is doing. Like I said I have some other irons in the fire with the car, but I try to take the time to go out, get the info then I can tell if what I am doing is helping or hurting.
1st the trans I feel maybe the biggest part of my problem. I believe it was slipping at the end of the year. The last time out to the track no matter how hard I stepped on it. Car couldn't get any faster, but slowed a few hundreths. I do think the converter is still a tad loose, but I will be adding a comp 212/212 cam and the .85 housing and I hope I will couple better on the big end with the combination of the 3. I will do all of these before I condeem the converter to a tighter restall. Who knows once I run it with all of those changes I still may tighten it up. 2400 may still be the golden ticket for a deep 11's with this setup, but only time will tell! Hey the housing is an easy mod to do that will definantly help the big end, but at what cost out of the hole?? Im looking forward to finding out this spring. :biggrin:
I meant to add you have a bb turbo anyways, you should still spool fine reguardless of the housing. That is a difference maker right there. Mine's just a journal bearing :frown:
You Z06 must not be stock, for your GN in its current config should walk all over it.
11.30s should be reasonable for you with a high 1.6 60' right now.
I used to have a Limit Eng TA61, it had the .82 exhaust housing, which was a special order at the time. That little combo went 11.40@119 on 27lbs. If the cam/converter is matched then the larger housing I bet picks it up 2-3MPH.
11.30s should be reasonable for you with a high 1.6 60' right now.
I used to have a Limit Eng TA61, it had the .82 exhaust housing, which was a special order at the time. That little combo went 11.40@119 on 27lbs. If the cam/converter is matched then the larger housing I bet picks it up 2-3MPH.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
You have plenty of converter for the .82 housing. It's worth a shot.
For best results with a stock camshaft I don't like to go over 2400 stall with a 10". The flash stall of anything higher is just too close to the 5200 rpm shift point for it to couple effectively. If the valvesprings are in good shape, the conveter is what makes it feel as if it's nosing over up top. It's still pulling hard but the load of 3rd gear at a low shift point loosens the converter up.
The 2400 stall has proven to work well with the 61 and 62bb turbo's. The problem is everyone is so used to seeing converters called a 3000-3200 when in reality a lot of them were only 2200-2400. A stock D5 is roughly 1600-1800 so to put in in perspective a 2800 is 1000rpm looser than a D5 and that's huge.
With a 61mm turbo, stock cam and transbrake I wouldn't hesitate to run a 2400 stall. It's still 600-800 rpm looser than stock so it will spool a 61mm.
JDSfastGN
Well-Known Member
- Joined
- Jun 16, 2001
Buttonnfly, I gotta say that its probably mostly a trans issue and not the turbo preventing the car from hauling up top. My dad and I both have a car with 6152s, one has been 124 and the other 126 and neither is a light weight car. They both have .63s. I would be curious how a .85 picks up. My car spools almost too fast
Buttonnfly, I gotta say that its probably mostly a trans issue and not the turbo preventing the car from hauling up top. My dad and I both have a car with 6152s, one has been 124 and the other 126 and neither is a light weight car. They both have .63s. I would be curious how a .85 picks up. My car spools almost too fast
I 100% COMPLETELY AGREE!! That is why the tranny in on the bench now! We had a few here in town going 10.90's-11.20's so it more than enough turbo to get me there. I am interested in hearing more about your combo's. pm me. Thanx J
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