high compression on turbo
11-30-2007, 09:07 PM
#1
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high compression on turbo I am going to be running in a heads up class that is limited to a 70mm and they are running in the low 9s and high 8s
Why is this a bad idea when limited to small turbo
What do they mean about when they say that the exhaust will start backing up
Why is this a bad idea when limited to small turbo
What do they mean about when they say that the exhaust will start backing up
11-30-2007, 09:55 PM
#2
High compression will always make more power than low compression, regardless of the type of induction. It's been dyno-proven. People just lower compression to combat detonation on pump gas. If you can run race gas, then by all means, build it 11/1 or higher.
For the turbo, the trick will be keeping the backpressure down. At first glance, I thought about the T70GTS from Precision. It will support 900 hp and has a relatively large turbine, for a 70mm. However, with the new BWA stuff coming out, I see where they make a ST70 that's available with a 1.25 AR exhaust housing. It's rated for 1000 hp, so it looks like a better choice than the 70GTS.
Being stuck with a 70 mm turbo, you should consider running smaller cid. Something under 300 cid would probably work best with the 70 because you can run a higher pressure ratio and the compressor would be more efficient.
1000 hp at 3500 lb would put you close to 155 mph, which would be good for 8's.
Mike
For the turbo, the trick will be keeping the backpressure down. At first glance, I thought about the T70GTS from Precision. It will support 900 hp and has a relatively large turbine, for a 70mm. However, with the new BWA stuff coming out, I see where they make a ST70 that's available with a 1.25 AR exhaust housing. It's rated for 1000 hp, so it looks like a better choice than the 70GTS.
Being stuck with a 70 mm turbo, you should consider running smaller cid. Something under 300 cid would probably work best with the 70 because you can run a higher pressure ratio and the compressor would be more efficient.
1000 hp at 3500 lb would put you close to 155 mph, which would be good for 8's.
Mike
12-01-2007, 06:46 PM
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70 Mm Inlet
No Limit On The Exhaust Side
Who Makes The St70
On The Subject Of The Exhaust Backin Up What Does This Mean And How Do You Fix It
How Big Of A Exhaust Housing Is To Big
We Are Limited To 360 Inchs At 3450 Lbs Heavy
No Limit On The Exhaust Side
Who Makes The St70
On The Subject Of The Exhaust Backin Up What Does This Mean And How Do You Fix It
How Big Of A Exhaust Housing Is To Big
We Are Limited To 360 Inchs At 3450 Lbs Heavy
12-01-2007, 08:00 PM
#6
BWA: http://www.forcedinductions.com/productsborgwarner.htm
Where did you get your terminology? Exhaust pressure is what makes the turbine spin. High exhaust pressure = bad, for obvious reasons. When installing a small turbo (i.e. 70 mm) on a large displacement engine (>~330 cid), exhaust pressure will be high.
With a 70 mm turbo on an LSx, I don't think you can go too big on the turbine side.
Mike
With a 70 mm turbo on an LSx, I don't think you can go too big on the turbine side.
Mike
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12-02-2007, 10:17 AM
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Hmm you can call Precision Turbo and ask for Joe, Alex or Brian, and see what they could whip up for you. I've seen this class run, I had no idea the turbos were that small. Looks like fun.
12-02-2007, 11:11 AM
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the class just cut the size of the the turbo from a 72mm to a 70mm because the turbo cars have won the last two championships and every race but one
I have always been a nitrous guy and have been helping tim hendrick (97green firebird)in this class since 03 when the class was called cheap street
we won the championship in 04
05 called street race and new rules
I have always been a nitrous guy and have been helping tim hendrick (97green firebird)in this class since 03 when the class was called cheap street
we won the championship in 04
05 called street race and new rules
Last edited by LS1LT1CAM; 12-02-2007 at 01:35 PM.
