yea basically. I have a POS beater car for the winter. But it's definately more than just a weekend car...and far from a trailer queen. I haven't even taken it down the track yet. I have plans to this summer tho, just so i can get some idea of what it can run.

 

11-1, higher octane, undriveable..............sounds like a shop that does very LITTLE with FI performance. There are a LOT of people on this board that run 11-1 comp with pump gas, that WHY we dick with the computer controlled FI, for the benifits. Id want head flow numbers, mid and low lift numbers espically. Anyone can port LT1 heads, but not everyone can port them properly. Give us head flow numbers and we can go from there. Also, i dont know if this would make a differance, but how much power will an engine gain after the rings seat and the motor "breaks in", as much as a motor can break in with a roller cam. No flaming, just adding my .02. Hope this helps Prorac1

 

Prorac1: That's what i figured about the 11:1 compression ratio (being able to run on pump gas without a problem...93 octane here in NJ, which is what I use anyways) Same with the engine breaking in...I don't imagine it gaining much if anything at all. As for the flow numbers, I posted them before...but they said 255-260 is what a set of their heads usually flow. They don't have a flow bench there...so i guess it's a guestimate from other ones that they have done.

 

Damn man, that don't sound right at all. My bud as a 94 LT1 motor in his 88 iroc and he did the LT4 conversion on using all the stock parts except for of course the LT4 heads, intake, he ported the MAF, PCM for less tune, 1.6 rockers, and lt4 hot cam. He is making 360 rwhp and thats on the stock bottom end. Something is definatlye up with a 383 making only 345rwhp.

 

Regarding some of the statements from your shop:

1. 11:1 requires higher octane, etc.

BS. I run 11.8:1 on a stock bottom end, with only 91 octane California MTBE fuel. Don't really even worry about the static compression ratio. It's purely theoretical. The thing that matters is the dynamic compression ratio, which takes valve opening and closing into account. A larger cam closes later in the compression cycle, which effectively lowers the compression. Second, the LT1 has reverse cooling, which allows you to run higher compression on the same fuel without detonation.

2. these cars are only peak HP.

BS. Take a look at the dyno graphs of the 400 rwhp cars. The torque curve is hardly a curve at all it’s so flat. I am not quite to the 400 rwhp mark, but I am close. My car made over 300 ft-lbs of torque at the rear wheels from 2000 rpm all the way to the 6400 RPM redline. That is streetable power in the extreme. The car drives almost like stock, although it does have some rough edges because of the cam. It's minor things that are easy to avoid by changing the way you drive a bit, like keeping the RPMs above 2000 as much as possible.

3. These 400 hp cars are not streetable.

BS. At Thanksgiving, I drove to Los Angeles airport to pick up my brother. I sat in stop and go traffic for an hour. Then, we drove over 600 miles that weekend both highway and stop and go. Finally, we spent another half an hour in traffic to get back into the airport. What more do you want? Fuel mileage? Over the highway I get 24-25 mpg.

If I had to guess, the heads they ported aren't that great. Especially if they don't have a flow bench. How else would they figure out if the porting work is effective? You can gain some by cleaning things up, but a full port job involves a lot more than that.

Heads are the biggest factor in making power. Especially on a 383, you need excellent heads to make big power.

The cam is also small, although if you have to pass smog, it's probably a good choice. If you don't have to worry about smog, then a bigger cam will net you some gains. Remember that a 383 needs more cam than a comparable 350, all things being equal. (or the same cam will seem "tamer" in a 383)

I hope this helps.

BRAD

 

They didn't even flow the heads afterwards?

"THey usually flow xxx" ???

That would make me nervous right there.

 

Cam specs: 540/220/230 112

Didn't you say you had the cc306? Those specs are definitely not the 306!

I don't know what cam that is. It looks like the 07-305-8 220/230 .510 lift but ground on a 112 instead of 114? Is it possible that they screwed up the cam timing and advanced the cam too far? You should be seeing numbers like 375-380 hp if it is the 306.

 

I originally thought that it was a cc306...but to be sure and to get more specific info for you guys to look at I called them. Those are the specs that he gave me. So..if I ask them to increase my compression ratio, will i see more gains? Also what would be involved in doing something like that? My main problem is that I don't know that much technical stuff...definately not enough to build the stroker on my own...i've got a lot of the concepts down...but not enough to tell the shop where they went wrong...etc. It's kind of a difficult situation because the guys are real nice and all...but it doesn't mean they won't try to pull a fast one or anything on someone who doesn't have as much mechanical knowledge as they do. I paid plenty of money for this build and I just want to try and get the gains I was hoping for & should have gotten with this setup. Again thanx for your input & advice...i just want to know what I'm talking about before I tell them to "fix" things.

 

To increase compression you have to use higher compression pistons.

 

They said that the compression ratio was originally higher than stock...but when they were porting the heads...they did something with the valves or something that lowered it back down to stock. But i guess you can't just reverse what they did. So basically my options for improvement are:

1. Retune the car...maybe I can pull out some a significant amount of HP & TQ there
2. Have the heads pulled and redone w/ a flow bench
3. Maybe change the cam...but that could compromise the car's ability to pass emissions as llafro stated

I realize that the cam is holding me back a bit, as many of you said, but I think it's a good cam for a milder 383...i'm willing to sacrifice that much for a bit of a smoother idle. But I still expected to be on the upper end of the 300's with my setup. Do you think it would be possible to pull something like that off with the current compression ratio, cam, and heads...simply with another computer tune?? Possibly get it up to the 370-380rwhp range? Or will something HAVE to be changed (cam & reporting heads...etc)??

 

I run 12.8 to 1 compression in my 383 and it runs great on pump gas..I have taken MANY 2+ hr trips and the car has never let me down..

Cody

 

Can you 383 guys with similar setups post up some your dyno graphs and a list of mods you had done? Thanx, info like that would really help prove my point to the shop.

 

IMO, while your compression ratio is lower than it could be, I don't believe that is the source of your problems. As stated above, your heads and tuning are likely holding you back, even with that cam. With something that small you probably won't see 400rwhp, but you should be able to see reasonably close.

 

The fact that they unshrouded your intake valve and opened up the combustion chamber a bit dropping compression ratios is right in line with what needs to be done to increase the intake flow when installing bigger valves. Your shop sounds to me like they know what they are doing. I think they may have erred on the cam selection. I would bet that if you really had the CC306 (and I would choose the 230/244 @ 114 one - it gives great power in a 383, and the added duration works wonders when you have a full exhaust on or plan to use nitrous sometime down the road) your car would be right there.

 

I'd say it was the cam. IMHO its way too small for a 383. Its not much bigger than a HotCam.

-Tony