madvette74

is there a compression limit you must have in order to use one of these? does anyone have one?

dewcustom

simply put the more comp you have the less boost you can run and as you have 10.5:1 that is very high to still run any boost 8:1 is what is normaly recomended for those chargers with 9 or 9.5 being the higher end before i rebuilt mine this last time i was running 13:1 but it was not good for driving around town so i shaved the tops of the pistons down and brought it back to 9:1 and plan on supercharging it but have not done so yet

hope this helps

norvalwilhelm

dewcustom are you saying you had 13 to 1 compression then you shaved the piston domes down to 9 to 1 compression?

dewcustom

that is what i am saying but i did not do it my self i had it done and then had the pistons rebalanced i dont know if this is somthing you may consider or what type of pistns you have but mine were very high dollor so i did not just want t replace them but if they had been cheaper i probably would have just put new ones in

norvalwilhelm

Wish I had known I could just mill the top off my 11 1/4 big block pistons when I needed a little less compression. I looked at that option but decided that once the domes were cut I would not have any metal left. I did section a piston and found the raised domes were also raise on the underside so if I cut the humb off I would be right through the head and looking at the crank.
I spent the $900 and bought blower pistons to be on the safe side.



[Modified by norvalwilhelm, 2:54 PM 9/14/2003]

WA 2 FST

I agree with dewcustom. I can speak directly to the Vortech blowers, as I have run several on several different vehicles ('90 Mustang 5.0, Saleen S351, '94 Lightning truck). They are very efficient, and will give you very good service life.

I had a little S-trim unit on my 302 stroker (331") that put out over 600rwhp and I was only turning 6000-6200rpm. Obviously, it had a good set of heads, intake, cam, exhaust, but it was the 14psi from the blower that made it tick. CR was 8.8:1 and I ran 93 pump gas if I wanted to.

I seriously considered putting one on my BB Stingray, but the problem is packaging. I think it would honestly be as easy to fab up a turbo system under the hood of a C3 since the blower sits out in front of the intake like a typical accessory and not on top of the intake, like Norval's positive displacement beast of a blower. :)

dewcustom

:iagree: with the turbo i think that might be easier than trying to fit a sc and all the acc. like the alt a/c ps and water pump

shawn_cake

I wouldn't want to pay Norval's gasoline bills!

:eek: YIKES! :eek:

fireball

Dewcustom - I am told the same procedure was done to my engine, but the previous owner has no idea of the current compression. Is 9:1 your estimate, or is there an easy way for me to determine my current compression give this piston mod?

MikeC

Yeah, you'd have to remove a lot of piston to drop it down that much... are you sure you haven't copromised the integrity of the piston? IF not that was a mighty heavy piston to begin with!

dewcustom

the way that i found my comp is mathmatical and i am not sure if there is a way to do it with out takeing off a head

as for the integrity of the piston, this was a reputable engine builder that many difrent people from all over the area said was the best sbc guy around and i was not crazy about it when he suggested it but he said he did it all the time w/o problems and that was two rebuilds ago. saw nthing funny when it was apart and it run very smooth infact if you were to put in some realy good ear plugs and go look at it runing you would think it was shut of and that is with it at any rpm. he did a heak of a job balaceing everything

WashingtonRacer

Milling the face of a piston "can be a very very bad idea, Expecially if your thinking about going Forced Induction. now it can be just fine in mild performance use, or lower cylinder pressures.

You will want right around 1/4 inch of crown thickness, Any less and if you lean out at all, expect to find a hole in the pistons. I think for the 500 or so bucks it costs for a good set of dished forged pistons, it's worth the money over risking popping the engine apart.

Twin_Turbo

I agree, I would like to know what brand and type of pistons you are running that aloowed so much material to be shaved and still remain integrity especially in a forced application.

I have 22 cc dished JE's


[Modified by Twin_Turbo, 3:12 PM 9/15/2003]