I have some spare parts laying around and was thinking they might make a good engine

I am busy working on installing the lift kit in my truck and came across these parts... Anyone have time to tell me if the pistons and rods would sit above or below the stock deck of a 350? If I had time I would crunch the numbers but I need to get my truck back together....

The rods are HEAVY duty custom versions from South Side Machine, they are beefy and weigh more than my Herche rods. I got both the rods and pistons for pennies on the dollar both new and never used.

Specs on the rods:

Length 6.600
Piston pic diameter SBC 0.927
stock width of SBB, and stock diameter on the big end...








Piston specs:

WRIST PINS = SBC DIAMETER of 0.927
BORE= 3.845
COMP. HEIGHT= 1.335
DISH = 6 CC

 

Re: I have some spare parts laying around and was thinking they might make a good eng

With the stock deck height spec, those pistons with those rods would be .328" in the hole.


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Buick 350 compression height= 1.805 These 1.335 difference of .470
Buick Rod 6.358 These 6.6 difference of .242

.470 minus .242 in the hole .228 more or less. could be as deep as .278 in the hole if the block has not been decked.


David

 

Re: I have some spare parts laying around and was thinking they might make a good eng

I do have a set of ported heads here that are 48 CC, with a 40 thou gasket and 50 thou cut off the block it would be 7.3:1 compression... Ad 25 PSI of boost and it might get interesting! The only reason I was planning to limit the boost to 14 PSI was my 9:1 compression... This engine would let me really crank it up and still have good street manners.

I was reading about a SBC with 7.2:1 compression and 24 PSI of boost making 1600 HP, really cool for a pump gas mild cam engine with a smooth idle.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Either way you are way out of range. If you're using those pistons with a compression height of 1.335 and the Buick Compression height is 1.805 you have a difference of .470 You would theoretically need a rod .470 longer than stock or 6.358 plus .470 or 6.828 of course none of these numbers take into effect the actual height of the block you are using. We know they vary greatly and most stock pistons set at least .050-.080 in the hole from the factory

Static compression would be in the 7.2-7.9 range depending on actual block height

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Gas mileage will be in the basement.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

10.188-6.600=3.588-1.335=2.253-1.925(half the stroke)=.328" in the hole.

You would have around 6.85:1 compression with the 48 cc heads and a .040" head gasket that is 3.890" dia. and .328 in the hole.

If you milled the deck .060" under 10.188" the pistons would be .268" in the hole for a compression ratio of 7.44:1 with the above figures.



Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

I agree with the fact that an engine in the 7.5:1 compression range would be less than optimal for street driving but for an all out drag car with 25 PSI of boost the lower compression would keep it alive.

I have the 9:1 street engine with Diamond pistons, Herche forged rods, and all the good stuff however I also have a girdle here for a 350 block and would like to setup another engine build to handle some serious boost.

It has been proven that 7:1 with big boost FAR out performs 9:1 with lower boost.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Derek I'm having brain farts today. Not a good day for me to measure anything more expensive than a wood 2x4 o No:

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Hey at least you are measuring!

 

Re: I have some spare parts laying around and was thinking they might make a good eng

If you bush rod pin end for .912 you could use wiesco ford 3.8 supercharger pistons at 1.615 comp height.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

He could even hone(.015" would be .0075" per side and the wrist pin locks would still work) the wrist pin holes out to .927" sbc size on those pistons,of coarse that would require new wrist pins.


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Would have to be an n/a motor with 13 cc dish compression will be about high.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

The piston would sit in the hole a bunch which is fine being an open chamber engine. 6 CC dish on the piston...

 

Re: I have some spare parts laying around and was thinking they might make a good eng

So are you going to assemble these parts in a block with around 7.5:1?

An engine and torque converter swap for a weekend of racing shouldn't be all that bad.

Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Well yes I have a dozen 350s here and I will swap them out when needed... Although the car is setup to be good on the street it is not like I am daily driving this thing.

I have a 3200 stall converter that is rated for 1000 HP and 100% lockup via flick of a switch on the dash so any engine combo should work well with that.

It is not like I plan to change engines all the time but it would not be a hassle to try a fresh one each summer.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

I say assemble it and after its tuned in,crank the boost up to 35 psi when you take it to the track and show up those LS1 turbo guys!:Brow:


Derek

 

Re: I have some spare parts laying around and was thinking they might make a good eng

Damn, I'm late to the game!

Fellow number crunchers, I salute you. :TU:


Gary

---------- Post added at 07:37 PM ---------- Previous post was at 07:09 PM ----------

How high can the 'boosted compression ratio' safely be? This is an area that I'm not as familiar with. I would think it would be around where the DCR should be, though the results from this calculator shows much different.


Put the figures in the DCR calculator and came up with this:

Static compression ratio of 7.44:1.
Effective stroke is 2.95 inches.
Your dynamic compression ratio is 5.93:1 .
Your dynamic cranking pressure is 107.01 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 25 PSI is 16.02 :1.

Using a 66* IVC cam (similar to a TA 212). This will affect the numbers, but I just wanted to toss something in to get some results.

Says the 'effective boost compression ratio' is 16.02:1 with 25 PSI boost.


Gary

 

Re: I have some spare parts laying around and was thinking they might make a good eng

16 to 1. I'm guessing 108 race fuel and a dam good intercooler. I'm assuming 16 to 1 boosted static compression.

 

Re: I have some spare parts laying around and was thinking they might make a good eng

I think that if I did put this together I would use it to do a few max effort pulls, it should run well with high boost... I still have this massive intercooler: