Thread: 454/502 hybrid custom build...

Tweet

hey guys,
i just recently picked up a 1997 Vortec 7400 series 454 shortblock that had 502 HO heads on it from the 502HO crate engine and to top it off a Arizona Speed and Marine Chevy TPI fuel injection setup thats basically the RAM JET.

Several questions...

I want to change the cam and the pistons in the shortblock considering its for a truck to bump up the power...

im looking into comp cams XR288HR and a set of forged pistons to bump up the compression...
the stock heads on that engine are 99cc chambers and make 9.1 CR...these 502 heads are 118cc chambers so what piston can i use to get around a 9.5-10.1CR???

Any helpful hints, ideas, .02, anything that can help....

Thanks guys...
JUSTIN

If I were building for a truck engine, I wouldn't want to increase the compression ratio over 9:1 because then you will have to use a longer cam which in turn will move the available power higher up in the rpm range, just opposite what you would expect from a truck motor.

Make up your own mind what you want to do, but if it were mine, I'd use the Keith Black #KB203 which will have thick rings (5/64ths") and make 9.0:1 with 118 cc heads. Then I'd call my favorite cam grinder and tell him what I wanted to do with the motor and go by his recommendation. Alternately, I'd use this cam which would give me a dynamic compression ratio of 8.00:1
http://www.cranecams.com/?show=brows...tType=camshaft

Here's the KB info.....
http://webpages.charter.net/beckracing/page36.htm#SECT3

hey guys...

sorry i didnt speculate on what im putting this motor in...
its going into my 68 camaro and im looking to get around 500FWHP or so out of it...

the shortblock is the vortec series truck engine and I was going to change out the pistons and cam so i can get the performance of a pass. car shortblock but with the strength of the truck engine...

so, in that case...i wanted to bump the CR to around 9-10.1 and use that cam i originally specified...

will that cam be too much for the fuel injection setup?? ive seen that cam in a ram jet 502 that made almost 600 HP so i thought that it would work well...

O.K., then here's what I would do to run the XR288HR cam.....
Bore the block to 0.060" over. Use Keith Black #KB207 hypereutectic pistons and zero deck them. These pistons have a 0.250" pop-up that occupies 25.5 cc's of volume. Use Fel-Pro #1037 head gaskets. This combo will yield a static compression ratio of 10.3:1 and a dynamic compression ratio of 7.926:1 with a piston to head clearance of 0.039". You should easily be able to run low-grade pump fuel.

yes thats is ok but i would do a srp piston and stay at .030. on the bore if you can the new blocks are i think are a bit thin the 1037 heads gasket is the one i would and have used

Thanks Pat. The only problem is that he's dialed in on that one particular cam and to use it properly, he needs the static compression ratio and to get there, he needs the overbore. I'm sure you are absolutely right on the thin walls and he just may have to settle for a little bit of a mis-match at 0.030" over and a little less c.r. Thanks again for your input. I value your knowledge.

[QUOTE=techinspector1]Thanks Pat. The only problem is that he's dialed in on that one particular cam and to use it properly, he needs the static compression ratio and to get there, he needs the overbore. I'm sure you are absolutely right on the thin walls and he just may have to settle for a little bit of a mis-match at 0.030" over and a little less c.r. Thanks again for your input. I value your knowledge.[/QUOTE ok i did not run the number on them he would have to cut the heads .that can open a new can of worms. but spr makes the piston for the edy heads never look in to it and can not tell you what the cr of them is he may want to look in to it ar JE piston web

i just looked at the SRP website and there is a piston number 212142 that will give 10.2 with a 0.030" overbore, so he could just use that one and call it good

yes that is the way to go

hey guys,
thanks for the quick answers...i am liking that cam b/c it seems to have made good power wit the RAM JET 502 and thats sort of what im building...
the fuel is no big deal to me, as with 10.1 or so i will run 93 anyway,
but i didnt want to dissamble the engine if i didnt have to...i was hoping to get a standard piston and just swap out the pistons...trying to take the easy way out since the shortblock only has 1,000 miles on it...