jimbjr

Well after a LONG road (over a year) I finally have my car back.
History - I was running a stock motor with a 100 shot, got bored, started running a 150 shot, got bored, did heads/cam and a 100 shot. After I picked up the car from getting the heads/cam installed I spun a bearing on the way home. I brought it right back to the shop, a crappy day was made a little brighter when I was taken for a ride in a LPE 427 TT, insane

I get the 383 done and have a DFI 7 installed (had a lot of tuning problems with the stock chip/heads/cam) I didn't want anything standing in the way.

I get the motor put in, the first dyno after the tune was horrible, something like 360-380 rwhp. This was on stock injectors and throttle body, LT headers, RT cats, xpipe, muffler elims.

I finally got a 58mm and 42lb injectors and sent the car to the Vette Doctors to tune the DFI. Pull the cats and the x pipe off and put on a borla exhaust. She put down 425 rwhp and ~385 rwtq, both numbers corrected. The uncorrected hp was 440. And it runs smooth as hell.

Once we put some miles on it, the 200 shot will be added, so I don't get bored.

the numbers are a little off from what I expected but after I put on some miles (and smiles) this season, I will send her in for a new tune and dyno this winter.

kmook

Nice, but what promted the exhuast change?

jimbjr

The exhaust was a little obnoxious with just the cats, the borla was put on to quiet it down, I didn't want the cats and the exhaust on the car.

Race-Prep

Well Jim,
Nice to see you keep the faith, we are very happy to see the results and there is probably a little more in there after putting some miles on it and another tune like you said. Have fun and when you get the juice on there, be sure to let those TT's have it!!


Bryan Wolter
Race-Prep Performance Engineering Inc.

Josh-'04 GTO

Why does your cam have so much more exhaust duration? Plan on a blower? Split seems a little much for an NA application...

jimbjr

Hopefully the Race Prep crew will answer that.

Jim

got_hp?

my guess would be for the nitrous.....like a blower, it likes the larger exhaust duration.

the cam is pretty darn small for a 383, im sure with a larger cam he would be well over 450rw.

4drLT4

The motor was designed with nitrous in mind.

Highlander

How much larger???? that is a cc306 cam with high lift and xe lobes. It should rev up really nice...

Shouldn't 330cfm heads yield easily 480-500rwhp?

AdioSS

Interesting...


I'm wondering what the compression ratio is?

got_hp?

230/245 isnt even THAT large for a 350ci engine............the extra cubes of the 383 can take A LOT more cam............the cam hes got in there now is basically like having the hotcam in a stock bottom end........it can take a much bigger cam and make a lot more power.

SStrokerAce

That cam is really not that small for that setup. I've seen LT1 383's put down more rwhp with less cam. That cam is about right for a street car. True you could put more cam too it, but that might not make more HP since the heads could be small for the size. If you were going to a much larger cam it would make more sense to go with a SR rather than a HR setup.

Bret

Highlander

This setup has been discussed before... I wonder how much those heads really flow... shouldn't 330cfm put down massive HP?

as maxracesoftware once put it

620x.87=540~550lift.

If those heads flowed 330@700 then at 550 they would flow 300s? to put an example??

300 x .257 x 8 x 0.85 = 524rwhp????? A nice rounding down 500rwhp capable?

LS6 are doing it with a 346 a 228 cam and 305cfm heads more or less...

jimbjr

This winter I might pull the heads and flow them. Just so the curiousity stops.

If the heads are flowing the numbers, couldn't the LT4 manifold be the restriction?

Jim

ChevyIron

Jim how much was the DFI setup cost?I am Having tuning glitches Glad to see the vette is putting up strong #s.