Pontiac - Boost Turbo, supercharged, Nitrous, EFI & other Power Adders discussed here.

          
Reply
 
Thread Tools Display Modes
  #41  
Old 04-25-2021, 06:04 PM
AIR RAM AIR RAM is offline
Senior Chief
 
Join Date: Sep 2002
Location: Homestead FL
Posts: 412
Default

Quote:
Originally Posted by charlie66 View Post
Is this motor a .030 over 455?

If you go to wallace. I put in 455 .030 over. 4.181 bore 4.25 stroke . 72cc chamber. 40 dish . .041 crush 4.300 gasket bore and .020 deck height. Its comes up 8.57 to 1 .
I do spend a lot of time on the Wallace Racing Calculator page, such a great resource.

Its 4.19 (+.040) / 4.5 stroke / 72cc chambers / 40cc dish / gasket = .061 thick 4.25 bore. the pistons will be around .005 in the hole.

So we should be real close to 9:1.

SPEED SAFE, NICK

__________________
"The grass is not greener on the other side, its just fertilized with different $h!t"
  #42  
Old 04-25-2021, 10:21 PM
charlie66's Avatar
charlie66 charlie66 is offline
Ultimate Warrior
 
Join Date: Dec 2004
Posts: 3,261
Default

Wow i forgot you have that 4.5 stroke .. So you're 505 at 8.92 to 1 .

I run 9 to 1 with a 3.75 stroke. Before that it was 10.2 to 1 .It worked ok at 20 psi or lower with out tuning issues . My cranking pressure was 190 psi. Now its 170 psi . But when i went above 20 especially over 28 psi i had gasket issues with the 10.2 to 1 . Later i did find out that the ethanol was only at 60% (e85 fuel) so that probably had alot to do with it but either way you look at it your tuning window gets much smaller when the base ratio is higher. The up side of it is you make more power per pound of boost. If you're not planing on going over 15psi i think it would work 9.2 to 1 with a .041 crush .

I thought you said you were using a .041 crush. Id use the .041 even though the ratio would be 9.2 to 1. Because the quench will still be in the so called safe zone. With a .060 you will be out of it being you;re .020 under deck .

I hope you dont mind me giving my opinion being you didnt ask me. I just wanted to share my personal experience with you ..

__________________
My Half AN Injun.....
  #43  
Old 04-26-2021, 09:22 AM
AIR RAM AIR RAM is offline
Senior Chief
 
Join Date: Sep 2002
Location: Homestead FL
Posts: 412
Default

Quote:
Originally Posted by charlie66 View Post
Wow i forgot you have that 4.5 stroke .. So you're 505 at 8.92 to 1 .

I run 9 to 1 with a 3.75 stroke. Before that it was 10.2 to 1 .It worked ok at 20 psi or lower with out tuning issues . My cranking pressure was 190 psi. Now its 170 psi . But when i went above 20 especially over 28 psi i had gasket issues with the 10.2 to 1 . Later i did find out that the ethanol was only at 60% (e85 fuel) so that probably had alot to do with it but either way you look at it your tuning window gets much smaller when the base ratio is higher. The up side of it is you make more power per pound of boost. If you're not planing on going over 15psi i think it would work 9.2 to 1 with a .041 crush .

I thought you said you were using a .041 crush. Id use the .041 even though the ratio would be 9.2 to 1. Because the quench will still be in the so called safe zone. With a .060 you will be out of it being you;re .020 under deck .

I hope you dont mind me giving my opinion being you didnt ask me. I just wanted to share my personal experience with you ..

All opinions are welcomed... This is what Forums are all about. The parts are already purchased and owned... so anyone with an opinion that changes the build will not be taken with any seriousness. However opinions to help move forward with the parts on hand are always welcomed.

I'm fairly sure the 4.5 stroke and 4.19 bore put me just over 496ci... I always wanted to go 500ci or more (symbolic reasons only) however the 496 was set only because the initial build was going to be with my 455 block and it was already @ .040 bore... So I purchased the rotating assembly for that and then got cold feet with running the 455 iron to power levels most sane people recommend against and decided to purchase an MR1 block. 496ci is close enough to 500 though.

I do have a set of .041 cometic gaskets however Hurb at Luhn Perf highly recommended that I run their boost specific 5-layer Cometic gaskets (made specifically for Luhn). He said the regular Cometic Gaskets do not go well with boost and their gaskets are specifically designed for boost and will handle the boost better. When I received them they measured a hair over .061... That kind of threw a stick in the spoke.

The pistons will be between .005 and .01 in the hole after the block is decked. With the Luhn/Cometic Gaskets It puts it in the 9:1cr ball park. My goal is to run between 15-20lbs but I dont think Ill go over 20lbs... if I ever do I may do a rebuild and and adjust the build for more boost.

This is all good dialog.

SPEED SAFE, NICK

__________________
"The grass is not greener on the other side, its just fertilized with different $h!t"
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 06:20 PM.

 

About Us

The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.

 




Copyright © 2017