Visceral

iTrader: (1)

I submit:


sorry for the blur, but you'll notive that the power peaks at 440 and then starts laying down after 5900 rpm.

I feel pretty good that the engine would have 460-480 in it if the power kept going up to 6500 of so.

The heads could be the culprit. They were horribly ported by ARE and MTI completely redid them and got alot more flow out of them. That may not have translated to power somehow.

Also, the car has never been tuned in person. The computer is a mail-order 387 proggie from MTI for a 387 with 91 octane gas. Theres clearly more room for spark advance. I used a MAF translator to get the A:F to 13.5 or so. There is an LS6 intake on it of course. 1 3/4" grott headers and a mufflex 4".

Ive been working hard at gatting the preload right on the CompR lifters. Currently, theres about 1/2 a turn of preload. One turn is approc .049" at the bolt, which is arounf .070 at the pushrod. Half of that is approc .035. I had .030 shims, but they are too much and I get lash.

Im wondering what's next. Adjustable rockers? HPTuner? a good session of Autotap? a bigger cam?

I like the drivability of the car, and I dont want to give it up, but the 387s have made alot of power in the past. I'd like to find the issue with the power falling off before I go too far into buying different stuff just as a patch.

chris

CHRISPY

That cam is too small. That is the problem. Throw a real cam in there and watch the peaks climb. That cam is actually small for aggressive HCI cars.

Go with something with at least 236 intake duration (preferrably single pattern or trad. split)

I would even try a 240/240 on 110-112LSA

What are your drivability requirements?

JF WS6

I'm going to say that the preload on the Comp R's might be costing you some. I've seen several threads where once they got set up right the motor gained 20+RWHP on the dyno.

According to your figures, I believe you still have too much preload. I thought they were supposed to be somewhere around .015 or so. Also excuse my ignorance if I'm wrong, but if you don't have adjustable rockers aren't the rocker bolts just tq'ed to 22ft. lbs. and you get your correct preload with shims/pushrod length? I think it would be a lot easier to get the preload right with adjustable rockers.

Chris is right also, that is a very small cam for a 382. I had that cam in my car previously (stock shortblock) and it only put down 420RWHP with Stage II LS6 heads through a M6 12 bolt. I really haven't been impressed much by the reverse split cams. I'd put something like a 242/250 XER cam in there, I think you'd see a significant gain.

Scalpel

iTrader: (4)

That cam is more of a streetable, no-worry cam. Also, it's never been dyno tuned. Those two are the most likely causes of your power that you're looking to gain.

Visceral

iTrader: (1)

Well, its an easy one... To be able to drive in stop-n-go traffic for miles.

I dont drag race the car... I have a mustang for that. I love midrange torque, and consequently dont want a car that is "soft" under 3500.

Maybe I'll find that in a Trex or a G5X3... I dont know. But I guess Im surprised that the cam would cause that fall off all by itself. I still have a feeling that something isnt set up right...

chris

CHRISPY

I dont think their is a serious valvetrain issue I just think the cam is too small. Even a standard split 230/230 on a 114LSA would give you more power imo.

Consider tryig a 234/234 on 114LSA. That'll give decent torque and good stop and go manners. It'll also move your peak up around 6300rpm in your combo (peak could vary a couple hundred rpm depending on a few factors)

Mike K.

I know APE had to get customer pushrods and shim the rockers to get the comp r's to work correctly in my motor. They also fell flat at 6k rpm and I have a 244 248 114 cam.

Linear Velocity

iTrader: (1)

Hey Chris, my 388 had a 230/236 .595/.598 114 lsa cam in it and peaked at 6250 rpms. So I think you're right were you should be peaking with that cam. Here's what I would to to max your setup:

1. Bigger exhaust. i.e. some 1 7/8" headers and a single cutout in the I-pipe or dual cutouts after the headers. That right there is an easy 20 hp.

2. Get better/nicer heads, stay with your cam. I made 511rwhp with just a little bit bigger cam than you and a nice set of heads and more CR. You have the cubic inches to make HP, you don't need a huge cam for that. See if MTI will work with you and maybe do an exchange for their stage II heads, I'd also look into more CR/running higher octane for more power. An 11.5 CR and a 91/103 mix I think would be good for some hp.

3. Get that sucker dyno tuned in person by a competant tuner. I can't tell you how much tuning has an effect on power and driveability especially with bigger motors. Hope this helps.

Visceral

iTrader: (1)

Thanks guys...

I dont know what the compression ratio is... but its pretty high up there. The intake didnt initally fit until we filed down the copper dowels, and the pushrods that are in there that fit with no shims are... 7.250" (no kidding) I wouldnt be surprised if it was 11.5-12.5. It does even wind slow when starting like my old hi-comp motors did.

Im pretty much stuck with these heads. Im not making nearly the money I used to and we have a kid, so another set of heads, even for an extra $1000 isnt in the budget. I can get a different cam perhaps if nothign else is wrong... but I really do need to enjoy the car for a little while and get some use out of all the money in this thing.

Im not sure who in the are can really do much custom tuning. Im pretty sure I need to just spend some time with LS1Edit. Iwas told there was one good tuner locally, so maybe I'll look him up.

thanks all... I'll get ti runnign just right and tuned and then perhaps go with a Trex or G5X3 or something larger than what I have.

chris

Linear Velocity

iTrader: (1)

If you're compression it 11.5-12.5 and you're running 91 octane you're losing some serious power by not bumping the timing and running 103+ octane. I think untuned with 91 octane my car put down something like 460 rwhp. Again if you like driving it, don't go bigger on the cam; you'll spend $1000 right there for parts and labor on a cam and maybe pick 10rwhp and possibly more driving issues. If you're stuck with the heads, you best bet would be going to a tuner have him bump the timing up to 23*-25* and run straight 103 octane. You can use torco racing fuel additive instead of running 103 all the time, or have a race gas tune and a street tune. Good luck.

Ragtop 99

iTrader: (7)

Even a 236/232 114 would open up your power and not kill drivability. Probably do it on a 112 and be fine.

Colonel

If I were doing an X1 on a 387 I'd do it on a 118 LSA to help it carry the power out higher. Talk about stealthy!

Visceral

iTrader: (1)

I live in Portland Oregon! A plain-jane Z28 isnt stealthy here... Just having a clean pewter SS with nice 17x11s in the back is more than 99.999% of folks up here normally see. Im not even stealthy stock. Maybe in the South or especially in Texas...that could be "stealthy".

Stealthy around here means a 300hp Subaru Forester.

Good thing is that you dont have to spend big money to stand out from the crowd.

Visceral

iTrader: (1)

So you got 51hp from tuning and octane? Now thats a good idea...

I'll have to look for that Torco stuff. Theres 104 around too, but its pricey.

How do you have 2 tunes? A high octane and a low octane table and let the computer decide? Im not sure Id want to go through the knock to kick it down to the low octane table.

But you do speak to my fears about the cam. The car is very drivable now. I'd be hard pressed to change that... although a cam really is just $400 for me, since I would do all the work. I can usually knock a camswap out in 3.5-4 hours taking my time.

chris

Linear Velocity

iTrader: (1)

Yeah I did pick up a lot from tuning and more octane. AS far as having 2 different tunes, basically I had to different LS1 edit files that I would load up. One for race gas (basically had about 25* of timing) and then one for street 91 octane (17* was the most timing I could run without detonation). I would invest in tuning/race gas first, because even if you get a bigger cam you're still going to need it tuned to get the power you want out of it. Then if you're not happy with the numbers I'd go bigger on the cam, I'd stick with a 114 LSA no matter what though for driveability's sake.