What size engine for my turbo ?
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From: New Zealand
What size engine for my turbo ? I am building a project car, road legal but will mainly be used for drag racing and events such as power cruise.
car will weigh around 1300 kgs and will be running a powerglide trans.
The turbo i'm going to use is an IHI RX8 ex CART car turbo, pretty trick bit of gear, Magnesium compressor housing, incinol wheels, titanium exhaust housing, triple ceramic bearing..., very compact as the compressor scroll is inboard of the backing plate, and only weighs around 7kgs.
Specs are hard to find, but measuring it, it has a billet compressor wheel, inducer = 77mm, exducer = 91mm.
turbine wheel inducer = 89mm, exducer = 79mm and has a 1.20 housing
rated to 1200 hp plus , from what I've been able to find the engines where 2.65 ltr v8 running up to 15,000 rpm and using methanol.
Bought the turbo off a mate that had it in a mild 5.7 ls1, made 620rwhp at 11psi but was quite laggy, but made huge gains for every extra psi added.
I have a new LY6 cast block , and my initial plan was to use a 4" callies crank I already have and build a 403 ci forged engine.
But now i'm thinking a std stroke 364 ci may be a better match for the turbo ?
would like to run around 20 psi boost and was hoping for 900 rwhp plus.
Thoughts ????
car will weigh around 1300 kgs and will be running a powerglide trans.
The turbo i'm going to use is an IHI RX8 ex CART car turbo, pretty trick bit of gear, Magnesium compressor housing, incinol wheels, titanium exhaust housing, triple ceramic bearing..., very compact as the compressor scroll is inboard of the backing plate, and only weighs around 7kgs.
Specs are hard to find, but measuring it, it has a billet compressor wheel, inducer = 77mm, exducer = 91mm.
turbine wheel inducer = 89mm, exducer = 79mm and has a 1.20 housing
rated to 1200 hp plus , from what I've been able to find the engines where 2.65 ltr v8 running up to 15,000 rpm and using methanol.
Bought the turbo off a mate that had it in a mild 5.7 ls1, made 620rwhp at 11psi but was quite laggy, but made huge gains for every extra psi added.
I have a new LY6 cast block , and my initial plan was to use a 4" callies crank I already have and build a 403 ci forged engine.
But now i'm thinking a std stroke 364 ci may be a better match for the turbo ?
would like to run around 20 psi boost and was hoping for 900 rwhp plus.
Thoughts ????
Thread Starter
TECH Enthusiast
Joined: Jan 2004
Posts: 608
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From: New Zealand
I believe there is a 2.0 AR housing I can get ahold of as well.
Your mate either had-
another issue or
the 1.2 was the problem
Or that 77mm compressor moves a lot of air and the turbine isn't big enough for a 347 due to the back press ratio going up on the bigger motor.
Bigger motor takes less boost to move the same amount of air.
But the turbine still needs the same inlet pressure to move that much air (simplifying) so exhaust reversion goes up and power drops.
You have a 77/79 combo.
A billet 76 mm with a bigger comp housing than your 77 will make 1200 hp on a 364 and about 30-32 psi right at the compressor outlet- but it's a 76/84 setup.
Not sure what turbine you have in your sig 76mm. Check the back pressure on your thumper setup and let it guide you.
The above 76/84 is a forced inductions S476-92 ETR HO special order not listed on their site. Does low 160's in the 1/4 at 3200lbs w/glide and 3.25's.
Search Stock48 screen name on this board.
another issue or
the 1.2 was the problem
Or that 77mm compressor moves a lot of air and the turbine isn't big enough for a 347 due to the back press ratio going up on the bigger motor.
Bigger motor takes less boost to move the same amount of air.
But the turbine still needs the same inlet pressure to move that much air (simplifying) so exhaust reversion goes up and power drops.
You have a 77/79 combo.
A billet 76 mm with a bigger comp housing than your 77 will make 1200 hp on a 364 and about 30-32 psi right at the compressor outlet- but it's a 76/84 setup.
Not sure what turbine you have in your sig 76mm. Check the back pressure on your thumper setup and let it guide you.
The above 76/84 is a forced inductions S476-92 ETR HO special order not listed on their site. Does low 160's in the 1/4 at 3200lbs w/glide and 3.25's.
Search Stock48 screen name on this board.
Thread Starter
TECH Enthusiast
Joined: Jan 2004
Posts: 608
Likes: 0
From: New Zealand
Your mate either had-
another issue or
the 1.2 was the problem
Or that 77mm compressor moves a lot of air and the turbine isn't big enough for a 347 due to the back press ratio going up on the bigger motor.
Bigger motor takes less boost to move the same amount of air.
But the turbine still needs the same inlet pressure to move that much air (simplifying) so exhaust reversion goes up and power drops.
You have a 77/79 combo.
A billet 76 mm with a bigger comp housing than your 77 will make 1200 hp on a 364 and about 30-32 psi right at the compressor outlet- but it's a 76/84 setup.
Not sure what turbine you have in your sig 76mm. Check the back pressure on your thumper setup and let it guide you.
The above 76/84 is a forced inductions S476-92 ETR HO special order not listed on their site. Does low 160's in the 1/4 at 3200lbs w/glide and 3.25's.
Search Stock48 screen name on this board.
another issue or
the 1.2 was the problem
Or that 77mm compressor moves a lot of air and the turbine isn't big enough for a 347 due to the back press ratio going up on the bigger motor.
Bigger motor takes less boost to move the same amount of air.
But the turbine still needs the same inlet pressure to move that much air (simplifying) so exhaust reversion goes up and power drops.
You have a 77/79 combo.
A billet 76 mm with a bigger comp housing than your 77 will make 1200 hp on a 364 and about 30-32 psi right at the compressor outlet- but it's a 76/84 setup.
Not sure what turbine you have in your sig 76mm. Check the back pressure on your thumper setup and let it guide you.
The above 76/84 is a forced inductions S476-92 ETR HO special order not listed on their site. Does low 160's in the 1/4 at 3200lbs w/glide and 3.25's.
Search Stock48 screen name on this board.
Mates car was m6 , I don't think it will be so bad with a decent converter.
I'm thinking the turbine flows pretty good being designed for an ultra hi revving methanol powered engine.
A forged 364 May be a better combo, but I already have a 4" striker crank and was keen on a 403.
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New that turbo cost close to 20k
I'd usually side with Darren here but that's a really sweet piece, I'd make it work with what you have.
Didn't those cart cars only use like 9-10 psi?
Might need a lot of exhaust flow and a small amount of boost to try and replicate what the turbo was designed for
I'd usually side with Darren here but that's a really sweet piece, I'd make it work with what you have.
Didn't those cart cars only use like 9-10 psi?
Might need a lot of exhaust flow and a small amount of boost to try and replicate what the turbo was designed for
Thread Starter
TECH Enthusiast
Joined: Jan 2004
Posts: 608
Likes: 0
From: New Zealand
New that turbo cost close to 20k
I'd usually side with Darren here but that's a really sweet piece, I'd make it work with what you have.
Didn't those cart cars only use like 9-10 psi?
Might need a lot of exhaust flow and a small amount of boost to try and replicate what the turbo was designed for
I'd usually side with Darren here but that's a really sweet piece, I'd make it work with what you have.
Didn't those cart cars only use like 9-10 psi?
Might need a lot of exhaust flow and a small amount of boost to try and replicate what the turbo was designed for
I believe they ran up to 21.8 psi with push to pass .
It's a pretty special piece , and I want to make it work, so my options are,
Forged 5.3, 6.0, 6.7, I have a used 5.3 block and a new ly6 6.0 block and want to leave as much meat in the bores as possible .
I'd go with the new Ly6 block and bore it as little as possible. The turbo will be happier and you'll have better block integrity. Crank the boost up till it makes the power you’re after. Can’t imagine that turbo would be anywhere near it’s limit at 20lbs.
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