The shop that is building my forged 383 LT1 told me he thought that a 10:1 compression ratio would be good. I am planning on running a 250 shot of nitrous in the future if this makes any difference. Does 10:1 sound a little conservative to any of you or does that sound about right? Thanks, Matt

 

Cam? Fuel? Don't even think about a 250hp nitrous shot on pump gas!

Rich

 

Well I used to run a 150 shot on my stock LT1 and never had any problems. We went with the GM 346 cam, to give you an idea if your unfamiliar with it, it is a little more radical then CompuCams 305 but not as radical as the 306. Will also be running a 3,000 stall with the cam. So you don't think even premium (93) will work with a 250 shot?

 

Made a mistake I said it was a GM 346 and actually it is a GM 846. Didn't want to confuse anyone.

 

I agree with rich, 250 shot will kill that motor, literally. A lower compression would be better maybe. Higher compressions do not give that much horsepower anyways, about .1 compression is worth around 1 horsepower. So you're losing 10 hp max going from 10 to 9.

 

To give ya an idea the fastest Pro Mod on hose in the country runs 15+-1 so compression ain't going to hurt it if ya don't rattle it,assuming your bottom end is up to it. Ya may have to go to another fuel and another pump for NO2 enrichment. Say, methanol which is perfect. Just get the right jet's.

Ya definitely want to start backed way off and sneak up on it.

The FIRST time ya rattle it with that much hose,schools out,see ya,by by engine.

 

I would say he's about 1-1.5:1 points low on compression.

If you are going to run N2O run it with some race gas.

Bret

 

 

So with the forged internals I have, not counting the crank which is a Scat crank will a 250 shot work? I put the forged internals in so I would be able to run a bigger shot. I can sure get race gas if that will be best though. Thanks for all the info.....Matt

 

I also concur with Bret. I think you should raise the compression as well. I really don't see the point of lowering the compression to lower than stock when running a larger cam, kinda seems like working backwards to me.

Jet that thing down for the street, and back up for the track. Also If you don't plan on doing that, I would look into a dedicated fuel system for the spray..that way you can run 93 in your tank, and some 110 in the dedicated fuel system.

 

A 250 shot on pump gas is very brave, or very foolish depending on your point of view. The CR is too low for the cam.

Rich

 

Does this builder understand stock your motor was 10.4 and that it's close cousin the LT4 was 10.8 bone friggin stock. Hell the iron head b-body LT1s were 10.0 and run perfectly on 87 octane. Sounds to me like your builder is behind a decade or two.

 

yeah if its not to late take your motor elsewhere

 

I am getting a solidroller 383 built with 11.0-11.5 compression and was planning on running a 250-300 shot.I figured it would be ok to run 93 octane when n/a and put like 30 bucks of 110 in when spraying

 

I'm don't deal with nitrous much but i was under the impression that when on the spray you could retard the timing and still run pump gas to a point. If it was me i would want to run a mix of 93/110 just to be on the safe side. Its cheap insurance.