[455TA]

I have a 481988 Block on the stand, completely deburred, ready to go to the machine shop. It is a two bolt block. I am wanting to build a shortblock to handle a decent amount of boost and street/strip duty. Would it be worth upgrading to a standard 4 bolt billet cap in the center 3 mains, for use with a turbo up to 15 psi? Or should I just use the two bolt caps and run arp studs? Would the block need to be cemented to the water pump holes?
It will have a Scat forged 4 inch crank, scat rods, and ross dished pistons. Will swap my E heads over to it from my current NA 455 and run a BW s480 Turbo with a billet wheel, along with an intercooler. It is fuel injected as well.

I would love to build an aftermarket block but can't see myself spending the $9100 just for a shortblock when I can build this 400 for half the price.

[73 TRANSAM]

If u only have two bolts drilled in the block. I would do a splayed and ask ur machinist to put a 3/8" dowel on those center 3 mains. U don't want to put hardblok on ur block as u need to dissipate a lot of heat with a turbo motors. Good luck on ur build. Keep it under 1200 hp and u should be good!

[GTOGEORGE]

Originally Posted by 73 TRANSAM

If u only have two bolts drilled in the block. I would do a splayed and ask ur machinist to put a 3/8" dowel on those center 3 mains. U don't want to put hardblok on ur block as u need to dissipate a lot of heat with a turbo motors. Good luck on ur build. Keep it under 1200 hp and u should be good!

Under 900 hp!



GTO George

[73 TRANSAM]

With the right combo, you can make 1200 hp at 5800 rpm. I think with turbo and that rpm, it will live with no issues. But I am no expert just base on what I see on how easy turbo on parts. Just don't go lean as u will have other problems.

[GTOGEORGE]

Originally Posted by 73 TRANSAM

With the right combo, you can make 1200 hp at 5800 rpm. I think with turbo and that rpm, it will live with no issues. But I am no expert just base on what I see on how easy turbo on parts. Just don't go lean as u will have other problems.

Yea if you don’t drag race it a lot.


GTO George

[JSPONT]

I would go with the three center billet caps at least. I do not like the splayed for 1 reason but won't post that here due to all the trolls. PM me if you care to here my experience.
Cap walk will happen with the 2 bolt caps even with arp studs. My car is at 10 psi for the past 2 seasons, on the street it is hard to use more than 750- 800 on an un prepped road.

[455TA]

Originally Posted by JSPONT

I would go with the three center billet caps at least. I do not like the splayed for 1 reason but won't post that here due to all the trolls. PM me if you care to here my experience.
Cap walk will happen with the 2 bolt caps even with arp studs. My car is at 10 psi for the past 2 seasons, on the street it is hard to use more than 750- 800 on an un prepped road.

Pm Sent!

[455TA]

Originally Posted by 73 TRANSAM

With the right combo, you can make 1200 hp at 5800 rpm. I think with turbo and that rpm, it will live with no issues. But I am no expert just base on what I see on how easy turbo on parts. Just don't go lean as u will have other problems.

Project Double Down is a good example. 900 hp and ft lbs of torque at 5500 rpm, with stock two bolt caps! I think billet 4 bolt caps should handle it under 6200 rpm with the 4 inch stroke. Will run E 85 with 200 lb injectors.

[Boostedbird]

Originally Posted by 455TA

Project Double Down is a good example. 900 hp and ft lbs of torque at 5500 rpm, with stock two bolt caps! I think billet 4 bolt caps should handle it under 6200 rpm with the 4 inch stroke. Will run E 85 with 200 lb injectors.

What is Project Double Down? Have a link to it?

[455TA]

Originally Posted by Boostedbird

What is Project Double Down? Have a link to it?

Here is the link - https://www.hotrod.com/articles/hppp...-installation/

[Tom Vaught]

I was at the dyno testing for the Luhn Performance Supercharger Test at Steve Morris Shop. The Headers used were my headers. The carb was not my carb (the article incorrectly says I modified it for boost). The Carb came from an outfit on the east coast that sold Boosted Carbs on the Turbo Forums. The CSU carb would have done a better job on the air/ fuel ratio with their Power Valve Modifications.

The engine still made 862 HP and 890 torque at a low rpm 5300 rpm for HP and 4800 for best torque.

The engine did have some Cap/Block "fretting" visible on the teardown. (Cap Walk) with the two bolt mains and arp studs.
ARP studs are not by themselves going to do the job. Luhn learned after this engine that the caps needed more Dowel length and support.

So a good article with only a couple of mistakes.

When Brian H ran his CSU carb on Steve Morris Dyno (different article) even it needed a slight Power Valve Spring Modification at the higher boost levels Brian H. was running at.

Just wanted to make the article accurate for the readers.

Tom V.

[Boostedbird]

Originally Posted by 455TA

Here is the link - https://www.hotrod.com/articles/hppp...-installation/

Thanks, I know that build. They could make a lot more power with a bigger cam, a better intake, a CSU carb, and V7 supercharger. The engine seemed to me to be pretty soft on power naturally aspirated. Probably mostly caused by the carb. High Performance Pontiac had a test mule 455" with a similiar cam and ported iron heads that flowed around 250cfm. Their engine made 500hp and around 550lbft with 9:1 compression. Double Down would have made a lot more power utilizing the heads better and with more supercharger, probably just with a bigger supercharger like the V7 YSI.

[Boostedbird]

Originally Posted by Tom Vaught

I was at the dyno testing for the Luhn Performance Supercharger Test at Steve Morris Shop. The Headers used were my headers. The carb was not my carb (the article incorrectly says I modified it for boost). The Carb came from an outfit on the east coast that sold Boosted Carbs on the Turbo Forums. The CSU carb would have done a better job on the air/ fuel ratio with their Power Valve Modifications.

The engine still made 862 HP and 890 torque at a low rpm 5300 rpm for HP and 4800 for best torque.

The engine did have some Cap/Block "fretting" visible on the teardown. (Cap Walk) with the two bolt mains and arp studs.
ARP studs are not by themselves going to do the job. Luhn learned after this engine that the caps needed more Dowel length and support.

So a good article with only a couple of mistakes.

When Brian H ran his CSU carb on Steve Morris Dyno (different article) even it needed a slight Power Valve Spring Modification at the higher boost levels Brian H. was running at.

Just wanted to make the article accurate for the readers.

Tom V.

Would have definitely liked to see it with a CSU carb on it! They are great carbs.

[Tom Vaught]

KEVIN AT CSU BUILDS A VERY NICE CARB. He uses a special power valve that only he will sell to you. That is why he is not #1 on my list.

ROGER AT C&S SPECIALITIES, IN MY OPINION BUILDS THE BEST ONE CURRENTLY (but his carbs are of the aerosol booster design) and some people like the conventional annular booster like Kevin uses. Roger uses a conventional Holley Power Valve.

Tom V.

[charlie66]

Originally Posted by Tom Vaught

KEVIN AT CSU BUILDS A VERY NICE CARB. He uses a special power valve that only he will sell to you. That is why he is not #1 on my list.

ROGER AT C&S SPECIALITIES, IN MY OPINION BUILDS THE BEST ONE CURRENTLY (but his carbs are of the aerosol booster design) and some people like the conventional annular booster like Kevin uses. Roger uses a conventional Holley Power Valve.

Tom V.

Looks like you got your name on that carb in the spec's at the bottom of the article !
"blow-through operation by Tom Vaught"