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  #31 (permalink)  
Old 05-07-2010, 08:04 AM
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Quote:
Originally Posted by ap72
I assume you mean the compressor?

The compressor is too small to make more than 425 in a 10psi intercooled setup as I outlined. If you want less than 425 then they are fine. Cleaning up the housings, the waste gate, intercooling, and getting a properly matched cam will make a difference. Keep in mind though you will be done making power by 5,000 RPM, after that you'll be heating things up too much and looking to break something.

Not a bad idea for a daily driver though as it will have spool from idle on up, full boost really early.



There was an article about a Pontiac 455 with a single turbo that was way undersized a little while ago- made about 750 ftlb at 3,000 RPM. Only made about 550hp, but the torque was huge. Great for a daily driver, bad for a race car.
Well yes the compressor plays into it but I was talking about the turbine "Hot" side. The flange is only T25 but i guess all i can really do is try it and see what happens.

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  #32 (permalink)  
Old 05-07-2010, 08:06 AM
How fast is fast enough?
 
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Quote:
Originally Posted by zildjian4life218
Well yes the compressor plays into it but I was talking about the turbine "Hot" side. The flange is only T25 but i guess all i can really do is try it and see what happens.

it is small. faster spool, earlier cut off. port the entrance out the best you can with some cartridge rolls (not bigger, just smoother like a cylinder head), and the waste gate, never go over 5000 RPM and you'll be fine.
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  #33 (permalink)  
Old 05-07-2010, 08:09 AM
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Quote:
Originally Posted by ap72
it is small. faster spool, earlier cut off. port the entrance out the best you can with some cartridge rolls (not bigger, just smoother like a cylinder head), and the waste gate, never go over 5000 RPM and you'll be fine.
Im prolly gonna run a tpi intake too so this might be a good combo. From what I have read those intake start packing up around 5000rpm but make good torque down low. Throw in a mild RV cam with some overlap and voila.
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  #34 (permalink)  
Old 05-07-2010, 08:27 AM
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Quote:
Originally Posted by zildjian4life218
Im prolly gonna run a tpi intake too so this might be a good combo. From what I have read those intake start packing up around 5000rpm but make good torque down low. Throw in a mild RV cam with some overlap and voila.

NO RV CAM. you'll want a single pattern, RV cams typically have a 10 split. It'd make a hell of a combo with a TPI intake, or a converted LT1 intake. you'll need bigger injectors though. not grossly bigger but about another 10 pounds/hr.

an ideal cam would be something like a summit 1069 cam.

You need to put this thing together and tell me about the amazing passing power on the interstate.
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  #35 (permalink)  
Old 05-07-2010, 08:32 AM
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Quote:
Originally Posted by ap72
NO RV CAM. you'll want a single pattern, RV cams typically have a 10 split. It'd make a hell of a combo with a TPI intake, or a converted LT1 intake. you'll need bigger injectors though. not grossly bigger but about another 10 pounds/hr.

an ideal cam would be something like a summit 1069 cam.

You need to put this thing together and tell me about the amazing passing power on the interstate.
I never knew that about the RV cams. Lol wow that is a low rpm cam. Perfect for this setup though.

So this is what I have right now. A 76-79 305 Truck block with stock 12.5cc dished pistons. Stock rods and crank also. I will go through and do bearings and rings.
I also have the TPI intake. Its off of a 86 305 camaro so its the pre '87 style cylinder heads. I believe they are 22lb/hr injectors.
I don't have a set of heads that will yield a small enough compression. I have 2 sets of 60cc heads, a set of vortecs that will not work, and a set of 882s.
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  #36 (permalink)  
Old 05-07-2010, 09:01 AM
How fast is fast enough?
 
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Quote:
Originally Posted by zildjian4life218
I never knew that about the RV cams. Lol wow that is a low rpm cam. Perfect for this setup though.

So this is what I have right now. A 76-79 305 Truck block with stock 12.5cc dished pistons. Stock rods and crank also. I will go through and do bearings and rings.
I also have the TPI intake. Its off of a 86 305 camaro so its the pre '87 style cylinder heads. I believe they are 22lb/hr injectors.
I don't have a set of heads that will yield a small enough compression. I have 2 sets of 60cc heads, a set of vortecs that will not work, and a set of 882s.
how low of compression are you wanting?

Go with 30 or 35 pound injectors.
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  #37 (permalink)  
Old 05-07-2010, 09:02 AM
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Quote:
Originally Posted by ap72
how low of compression are you wanting?

Go with 30 or 35 pound injectors.
I was shooting for 7.5-8.0:1
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  #38 (permalink)  
Old 05-07-2010, 09:20 AM
How fast is fast enough?
 
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Originally Posted by zildjian4life218
I was shooting for 7.5-8.0:1

you need a 70cc chamber... port the runners the best you can on the 882s and run them. They're not a great head but you have to keep in mind your required flow isn't huge.
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  #39 (permalink)  
Old 05-07-2010, 09:31 AM
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alright cool. Should I mill the heads some to get them down to the 70cc? Also I thought the 1.94 x 1.5 valves are too big and will hit the bores of the 305?
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  #40 (permalink)  
Old 05-07-2010, 09:37 AM
How fast is fast enough?
 
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Originally Posted by zildjian4life218
alright cool. Should I mill the heads some to get them down to the 70cc? Also I thought the 1.94 x 1.5 valves are too big and will hit the bores of the 305?

they aren't too big, but they are close. 194 is as large as you can go. DOn't mill the heads- they're already thin, and you'll just have to run more boost to compensate, crank it up to 13-15psi. Now you're looking at 475hp... dang... Just be sure to clean up the exhaust and intercool it like I have mentioned several times, its VERY important to keeping heat down and making this thing live.
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  #41 (permalink)  
Old 05-07-2010, 09:41 AM
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Quote:
Originally Posted by ap72
they aren't too big, but they are close. 194 is as large as you can go. DOn't mill the heads- they're already thin, and you'll just have to run more boost to compensate, crank it up to 13-15psi. Now you're looking at 475hp... dang... Just be sure to clean up the exhaust and intercool it like I have mentioned several times, its VERY important to keeping heat down and making this thing live.
Lol ill be at 7.25:1 with the following

76cc heads
12.5cc pistons
3.736" Stock Bore
Gasket - .030" x 4.200"
Deck Clearance - .025"
Stroke - 3.48"

Will that be alright or is that too low?
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  #42 (permalink)  
Old 05-07-2010, 09:50 AM
How fast is fast enough?
 
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Quote:
Originally Posted by zildjian4life218
Lol ill be at 7.25:1 with the following

76cc heads
12.5cc pistons
3.736" Stock Bore
Gasket - .030" x 4.200"
Deck Clearance - .025"
Stroke - 3.48"

Will that be alright or is that too low?
I'd run a thinner gasket. a felpro 1094. .015" thick. Also have your heads surfaced, it'll drop about a cc or two.
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  #43 (permalink)  
Old 05-07-2010, 12:30 PM
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Quote:
Originally Posted by ap72
I'd run a thinner gasket. a felpro 1094. .015" thick. Also have your heads surfaced, it'll drop about a cc or two.
Alright cool that will sit me at about 7.5:1 This should be a fun little torque monster. I had 2.41 gears in my cutlass. I wonder how this would have done with those gears.
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  #44 (permalink)  
Old 05-07-2010, 12:32 PM
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anything more than about a 3.55 gear is too much for this type of engine.
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  #45 (permalink)  
Old 05-07-2010, 12:39 PM
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Quote:
Originally Posted by ap72
anything more than about a 3.55 gear is too much for this type of engine.
I like the long pull of a real high(numerically low) gear. I had 2.41s in my car and they were fun. Went from 1st to 2nd at 85mph turning 6500rpm. Maybe ill put a 3.08 behind this setup
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