I'm at a cross roads right now and not sure which way to handle this. Maybe I am all wrong,.. hopefully someone can set me straight.

I have a nice C9OE 69 windsor block. (Thanks Raymond). My plan is to set it up to be boost friendly. I want to do a carb'd TT build. The 69 blocks are a 9.48 deck block and will be nearly zero deck with pistons. I'm dropping the whole nitrous idea and will be selling my cheater kit. I fell this block will live a lot longer at 800 hp using turbos then with nitrous. Plus,.. its there anytime I want it.

My problem is getting the compression low enough to be boost friendly.

A 427w will use a 4.171 stroke. My block will have a 4.060 bore. I'm going to be using AFR 225 heads. The largest combustion chamber they have is either 68cc or 72cc with mainly 68cc on the market right now. The biggest dish I can find is -22cc dish piston.

Doing the math,.. I dont see how to get less then 10:1 CR using a very thick head gasket,.. which I dont think would be a good idea for boost. I dont understand how to use over lap on the cam to lower compression. I'm going to build this motor myself,.. this is just something I must do. But I'm trying to gather as much information as I can and this one problem has me stumped.

A 408 uses a 4.0 stroke,.. still not enough to get the compression down to where I want.

The only option I see would be to build a 393 using a 3.85 stroke. That would get the CR down to 8.6:1. I am aiming for 8.4 - 8.5:1 CR. That is what I want,.. I dont want to run boost on 9:1 CR or higher. I want to run as much boost as I can on 93 Octane.

Can anyone give me some insight on how to build a 427w using 68cc AFR 225 heads and build the motor to get 8.4 - 8.5 CR? Should I give up on the 427 and just go with a 393?

Thanks,
Hurst

 

Incorrect.
69 and 70 are 9.48. 71 on up are 9.5. Intakes are the same for all 351's. I've already had 2 other 351's,.. a 70 and a 78. Used the same Performer intake on both.

Cleveland blocks are 9.2


Hurst

 

Still doesnt help me understand or figure out how to reduce the compression,..


Hurst

 

Did you click on the box for compression specs.
Click on the engine kits, I linked pistons, sorry
http://www.probeindustries.com/category_s/301310.htm

 

Cometic makes head gaskets all the way up to .125 thick.

 

The first link you put up just shows Ford pistons for sale.

The second link is for stroker rotating assembly's.

Am I missing something?


Hurst

 

Is that compressed thickness?

Technically with a -22 cc piston a .11 thick head gasket would put me at 8.5:1 CR with a 68cc head. In your experience how would a gasket that thick last under boost? I was always under the opinion that a .025 would be max for a boost application.

Hurst

 

First thing first..... If you want to make say 750-800 rwhp with a turbo/turbos, there is no reason to build a motor that big..... You could easily make enough power to break the 69 block with a 357, this will solve any compression issues..... Also I would seriously consider 1 decent size turbo rather then 2 smaller ones, you can make big powa with one in the 80mm range..... Just look at Wendy's car, it has an 80mm/363 combo that currantly makes 750 on relatively low boost and there still tuning.....

 

I dont have John and Wendy's budget,..

So my turbo's will be 2 turbo's sourced from any Buick 3.8's I can find in the junk yards. I dont know of anything else with a single turbo that would be large enough that might end up in a salvage yard for my application. If I found something I wold certainly try to make it work with a single.

I'm hoping to be able to do the entire turbo set up (Not including the carb) for between $1000 - $1500. The most expensive parts will be the manifolds and intercooler. The piping and welding I will do myself.

Also I want to try to keep the motor on pump gas for the most part,.. so 10 - 12 PSI will be pretty much the main stay. I may try to reach 15 PSI on race gas and see where that takes the motor if the turbo's are capable of pushing that much boost. Thats my plan anyway. Always subject to change if I find out something wont work.

I havent purchased anything yet. I'm still trying to figure the build out first. I want to have a feasible build with a realistic goal. Hell,.. I know next to nothing about turbo's. Just started reading up on them about a week ago when I decided I wanted to try it. Talking with Shinyside a couple weeks ago got me thinking about it. I got to thinking about the costs involved with filling a nitrous bottle twice for a single day of racing,.. I decided that doing a cheap junkyard turbo setup would be a cheaper way to go. This entire build is going to take me well over a year to complete with my income. So I have time to read,.. take in opinions,.. and learn as much as I can before deciding on a final course of action to take.

I am definitely open to suggestions. I dont know Jack about Turbo's. I just figured that 2 x 3.8L = 7.6L and that would be my best bet to making it work. If I could do it with smaller turbo's like say 2 turbos from the 2.2 Chrysler cars I would try that,.. but 4.4L doesnt seem like it would be enough. Or am I completely off track with this kind of logic?

The more I'm reading the more I'm thinking the 392/393 will be the better way to go.

Hurst

 

"I" have never ran them first hand. However i spoke to Chad a year or so ago about this same thing. They were running them on their big hp/turbo car and he said they never had an issue.

just trying to pass along an option.....

oh and yes that's compressed