So i have in mind of building a 408ci shortblock with a 12:1 compression and using pump gas so i could drive it on the weekends. A couple friends of mine told me the dome piston is a bad idea an so is a 12:1 with pump gas. I wanted to know what you guys thought of this set up and what advice you have to build a 12:1 with pump gas. If im not able to use 12:1 with pump gas i was thinking of just goin with a 13:1 n high octane weekend warrior

Wiseco +5cc dome pistons
.040" gasket
72cc heads

 

im running a pretty close set up to 12;1 .. mine is 11:8:1 compression using 91 octane my heads are 64cc-62cc i forgot with diamond dished pistons..First decide what u really want man..

 

12:1 is not a good idea for pump gas ( typicaly 91-93 octane), 13:1 is a PIA to run race gas in a street car and do you know race fuel cost? I would re-think it. What are you trying to accomplish?

 

What kind of power did you make with that set up.?

 

Thats what i was told that it wasnt a good idea but i read a couple threads were people were using pump gas on a 12:1. My goal was to build a streetable race car (not a DD) with good power so I figure the best thing was a 12:1 compression.

The idea of 13:1 was only if I was to build a stright race car and not be able to drive to the mall or cruise it on the weekend

 

You can get by with 12:1 on 93, Just depends on what kind of cam you run. Based on what you are saying I would say set your sights a little lower. You can make good power with lower compression... It all depends on the combination.

 

Haven't took it to the dyno yet cause I have a shitty 4l60e and I'm afraid of breakin it on the dyno..but give or take Nick at newtech said around 480ish rwhp n/a and around 700-750 on bottle

 

thank for the replies so far guys.

Now what do you guys think of dome pistons and the set up
i posted above.?

 

Yea well you dont make more power by hanging the intake valve open to relieve compression and if your backing timing down your not making more power either.

 

Listen to the guys who said it's not a good idea. Hi compression is not a bragging right. 11:1 on 91 octane is what we recommned and HKE has some of the fastest N/A cars you will find. 9.4 seconds on 91 octane with a 3300 lb car.

 

you could get away with it with a big enough cam and easy on the timing for street driving

i ran 11.8:1 on my 408

 

Lower the compression and supercharge it if you want the best of both worlds. Then you can run 87-89 during the week, and 91-93 at the track. There will be plenty of power for you with that set-up.

 

as said, don't risk having to run race gas just to get a little more compression. keep it at a safe compression and use other parts to make the power your looking for.

 

My old 408 was 12:1. I raced it on 104 (really 105 my track doesn't have 104 so I had to mix 110 and 100) (1/2 and 1/2) but anyway, I did drive it on the street with pump gas all the time BUT BUT BUT, you cannot go WOT on the pump gas if it's tuned on the race.
If you go 13:1, you'll have to drive it on the race, maybe a race/pump mix but still can't go WOT unless you have full race gas in it. That's how I did it anyways. Now I have 13:1and drive it on the full 110 octane or a 110/93 mix. I can't go WOT on the street anyway, unless I want to kill myself.

 

I did some research on 11:1 and ive seen some people making some good
power. But how much power difference would it be from 11:1 to 12:1.?

 

What were the specs and what kind of power are you making.?

I wish i had the money for a supercharger. For now im sticking to a 408
and nitrous

This is the type of set up i had in mind. I wasnt planning on racing it with pump gas cause im gonna be using nitrous, i just want to be able to cruise the car. What was the set up on your 408 and what kind of power did you make if you dont mind sharing or you can pm me.

 

Really you should run flat top pistons and run a smaller chamber in your heads to help your quench.

 

Listen to 99blancoss. He will keep you pointed in the right direction. Keep it at 11.0 to 11.5. Spend the money on some good heads and a good cam.

Bumping the compression from 11.0 to 12.0 is not going to net you much power worth the cost of having to buy/find racefuel. You can run 11-11.5 and make the power you need.

 

I run 11.38:1 CR on my 408 with 93 octane. I have TFS 235cc heads milled to 64cc and a custom cam(246/254). I put down 515rwhp with only a little bit of tuning and a shitty intake setup. Im hoping for 550 rwhp when its all said and done. Listen to 99blancoss he knows his ****

IMO there is no point in running that high of compression in a street car. Too expensive and too much of a pain to switch back and forth from pump to race gas.

 

https://ls1tech.com/forums/dynamomet...o-results.html