dhirocz

I strapped it down and got some numbers out of it...all pretty much the same from the 3 runs we did. No dips or anything in the graphs showing a problem...
Max RWHP: 383.4
Max RWTQ: 382.1

The car started blowing some brown smoke out the tailpipes over 5k RPM and at release, blew white smoke. Nothing in the graph shows this.
Air fuel ratio starts off over 15 at 2k rpms (maybe my part throttle stumble between 2000-2500)?, sharply goes down to 12.5 at 2500 and flatlines out at 12 to 12.2 through the entire RPM range. It does kind of fluctuate a little where the cam drops off at 6300. The redline on the chart is at 13:1. Most every part in the drivetrain is new. This is through an M6.

Anything sound wrong here? The motor is a 382ci LT1 (3.8"stroke/4.00"bore)with LE heads (270/195), 233/239/112 cam, 10.3:1 cr, LT's, borla (open), 52mm TB, and 30# SVO's. Tuning my madz28.

Sounds good though. Anything stand out to you guys? I was expecting around 400/420 at least. The smoke bothers me a little bit since it was kind of excessive on acceleration...

JKDZ28

Hmmm...I think your down some HP, with a 6speed and everything.

1racerdude

Not bashing but ya asked.

Compression to low
Heads to small
Cam to small(may be OK with more head flow)

All to small to make 400/425RWHP.
A good dyno tune might net ya a few more poney's.
Ya might call Ion and see what he says.

Kryckter

Just go through everything and check....
AFR is a little off - tad rich, Gain a few...
52mm TB....needs a 58
Camshaft....May have done a different one there, Could be missing some HP...

But still, Sounds real good with TQ just as high as HP....
Get the small stuff tuned in and it will perform....

Joseph

madwolf

The air fuel ratio isn't bad at all on your run, but there is 5-15 RWHP to be gained from a little more tuning.

You might want to try a run with the cutout open and one with it closed. My 233/239 makes more power with the cutout closed. It also made more power with a 48mm versus a 52mm TB, but that was on a 350, so you can try going both extremes. (48mm first, then 58)

Email me the graph when you get a chance.

dhirocz

I built the motor with the intention of putting a super or turbocharger on it which is why the compression is so low...I wouldn't put it on where it is now, but it would be mostly a cam swap and head gasket change to get me where I wanted to be. I didn't think I was going to be loosing that much HP.

I've had cars without cats before, but with the engine idling, I can barely get anything out of my trunk, it runs so rich it burns the eyes.

I'm mostly concerned right now about smoothing out the driveability and getting as much MPG out of it until I get everything together for my turbo swap. I'm kind of curious to see if the heads will support the power levels I'm wanting to achieve with the turbo.

Still no clue on the brown smoke.

brain

Wait, so you went with 10.3:1 for a turbo or supercharger? That is too high if it was an intentional buildup. A cam swap and a head gasket change to get where you want? The cam swap won't do anything for the CR, but the headgasket might put you at what, 9.8 or 10.0 at the best? Good luck with boost on that setup.

jkipp84

That's still a good bit of power and should make for a fun ride!

FastZinTennessee

You're compression ratio is in between what you'd want for N/A and for boost. Unfortunately it looks like your compression won't really lend itself to either one

Those numbers aren't bad, I'm sure it's a blast to drive. What's the lift on your cam?

dhirocz

I wasn't planning on more than 6 psi intercooled...that's why the compression is where it is. The head gasket change can make it lower if necessary, it's pretty thin as it is.

I think my heads are starving to supply enough air for HP on the stroker, as max HP comes in at 5700, even though power doesn't fall off until 6250.

Only thing I'm really disapointed at is why I am not making more torque...Maybe the wrong cam? I'll have to look further into my combo I guess and make a few calls. If I'm going to change the cam I may change to one that's boost friendly as well.

med_reject

post a graph. there could be other problems, like springs, rockers, ignition. It could even be the way that dyno is calibrated, you'd know by what other cars are putting down.

JBird33

Maybe I misunderstand you or something, but wouldn't you want a thicker gasket for lower compression?

ABA383

What was done to your heads when Lloyd did them? Also you don't need a big cam to make big power. Bigger cams don't necessarily make bigger power. My 383 has LPE/E.B. Porting ported heads w/ 2.00/1.56s and a somewhat small Joe Overton cam (226/234 .56X/.56X lift) with 11.2:1 comp and it made 400rwhp 430rwtq (N/A) on a partial dyno pull with a rich 12:1 a/f ratio just before the driveshaft broke in half...and it was in an A4 car with 3600 stall. Theres more in the tune, too.

I know you want to run with a blower, too, so we are not comparing apples to apples, but I do agree that if you are going to add a blower you should drop to a lower comp ratio. You'll make more power with a lower ratio and higher boost, than you will with high comp and lower boost. If the cam you've chosen was spec'd by a reputable person/shop and is blower friendly then I guess you'll be fine once you add the power adder...Good luck...

--Alan

JBird33

I think all that the blower-friendly cam is going to buy you is less bleeding-off of your boost due to valve overlap. It is going to do nothing for you as far as how much boost you can run given a certain compression ratio.

dhirocz

I might put the 233/239/112 up for sale and get a 230/236/114 that's a little more friendly to my setup. I think the charts show that the heads are done making power around 5750. I'll get what I can, tune it, and go from there. To do any more compression work, I'd have to shave quite a bit off my heads since the pistons are dished and I'm kinda reluctant to do that.