Well I got a call from the tuner (Mike from Rapid Motorsports) today. He was complete with the dyno pulls.

Here are the details or the car/motor:

200-4R transmission with a SS3800E converter
408 iron block
Solid roller cam 248/254 .644/.660 112+2 (Spec'd by Patrick G)
Dart Pro 1 Heads ported by TEA(Flow about 365 at .600)
Comp 1.7 adjustable rockers
Comp 944 springs (these are BIG boys and should never float)
LS6 intake with a 90mm throat (I know this is robbing a few ponies vs a FAST but shouldnt be more than 20ish tops)
1 3/4" Hinson headers to a 3" Y pipe no cats (I Have 1 7/8" ready to go on the car but again doesnt account for that much of a loss)
42 lb injectors
(I am using a 90 degree bent intake, that is temporary until the Samberg setup arrives)
SCR 11.6:1 DCR 8.9:1
AF ratio was solid at 128ish and the timing was at 27 degrees

One last thing about the motor, I mistaken had the drivers side coil pack flipped over (Nasty N8 valve covers and I flipped it, Mike found it but the car had been run a couple times at idle to load it on and off trailers). Hopefully the cylinder walls arent washed out but I wouldnt think that would cost me all the power either.

Well the dyno results are less than encouraging and I am curious if anyone has seen anything like this before.

Final numbers were:

RWHP: 345
RWTQ: 318

As you can see the dyno graph goes nuts. No one I have talked to has seen any such thing.

Any ideas?

Mike said the car pulled strong and felt a lot stronger than the numbers indicate. He said it wasnt breaking up at all or showing any strange signs. Only thing that happend was right as it fell off the AF went a little rich.

In the picture, because I didnt get the rpm designations in the pics, the far right dashed line (not the scale all the way to the right) is 6000 RPM. Next one to the left is 5750 then 5500 then 5250 then 5000 and the far left is 4750.

I am at a total loss. This motor should be a 550rwhp motor in a M6 car and in the auto should still be in the 500 range, at LEAST 475. I am 100-150rwhp low. Tracks dont open up around here until next weekend. If I could run her at the track I could see what the MPH (Should be in the 128-135 range as my car weighs less than 3000 lbs) was and it would tell me if everything is ok and the dyno is reading wierd because of the trans/converter etc.

My thinking of the possible issues are:
1. Motor/trans is fine, dyno is making it read strange.
2. Rear wheels were slipping on the dyno. I have fairly low profile tires (35) on the car so maybe.
3. Valvetrain issue. Springs? Geometry (the geometry was verified by the machine shop that assembled it)
4. Trans is shot. Causing a lot of drag.


I am at my wits end. This motor has been a headache since I bought it (I originally bought it as a race motor but it never ran right for various reasons). I am about 2 seconds away from pulling it and dropping in a stock bullet. I havent enjoyed the car for the last 2+ years because of stupid motor issues.

Any thoughts or idea?

Any input is welcome.

 

Is this Ryan with the silver 7? If so give me a shout! looks like serious valvetrain problems just to start. theres no such thing as springs that should float, if the combination of parts is not happy its not happy.

it wouldnt be tire spin with an auto, it would spin on the converter flash at lower mph. its already hooked and would take double the torque to spin them at 100+ mph than it would flashing a converter at 50

 

First dont get frustrated. Do some simple testing ,start with a compression test of all 8,next do a leakdown test.Something is holding it back,stick with it untill you find the problem.Check back with dyno to see if they are having problems.

 

Wow that is down serious power. What did Mike suggest or recommend? Also why the solid roller for such a mild setup?

 

Coupla things from the v8rx7board:

 

I'm with this guy. ^^^

 

I don't have much to offer, but the graph is pretty telling though it lacks alot of info. Looks like it is pulling good then all of the sudden falls on it's face bad. This wouldn't be because of a restrictive intake or headers. They may cost you a little power but would not have the effect indicated on the graph. I would think this is most likely not a mechanical issue with the motor, as it appears to happen at a fairly low rpm (rules out valve float), and a dip that severe that was caused by an internal engine problem would most likely have detonated the motor or seriously damaged it. But it could be a mechanical issue behind the motor - converter or trans. If this isn't the case I would still be suspicious of fueling or spark. While #1 may have a steady 27 degrees, what about the other cylinders? Is it missing at all in the upper rpm range? The other potential is the dyno itself is the culprit, although you should know this as soon as you try another. If all else checks out, the next thing I would do is pull some timing. Target about 22 degrees for a pull and see what you get. Perhaps it's detonating severely, which can cause this, and if you don't have knock sensors and didn't hear it you wouldn't know. My DCR is a little less than yours and I cannot run this much timing at WOT.

 

what rocker arm set-up are you using?

 

Whats your valve lash set at?

 

We're going to take care of Mike We're pulling the motor in a few weeks and will refresh it and go with the proven Dominator 2 lobes with a set of TFS heads. I have to tell you guys, this car is really beautiful. Noisy and cold though...haha.

 

Why not take it to the track? Thats what counts...right?

 

why bother, with 350 hp it will go high 11s

 

Can't throw the definitive smack down with only 350.

 

Yep working with Mike to finally after 3 years, of chasing my *** with this motor, fix it.

It ia all the best parts in the car but something isnt working with something.

The car does get some serious attention though