429firehawk

Dyno Tune at Speed inc. yesterday. dyno sheet attached

short list of the parts involved

2001 Firehawk

429 LS3 12:1 on 100 octane Unlead
4L80E with 4200 stall (stalls at 3800)
9" moser 3.89 gear

Trick Flow 235 heads

Cam: 624/624 lift
duration intake 251/ex. 259
LSA 111.0

SD tuned. 92m fast intake with 65lb. injectors
MW throttle body
Fast toys lid with straight tube

QTP headers and y pipe with gutted cats magnaflow cat back

Thought i would be closer to 550 -600hp range. power seems to die off at 6k. any ideas as to why?

your help is appreciated.

MikeG

iTrader: (33)

Stalled 4L80E will hurt power a good bit, the converter was locked for the pull, correct? What size primaries do those QTP's have?

Gabbiani

iTrader: (20)

I would rather see a 102 on it but....
The dips in tq worry me a bit. Have any logs of the pulls? You usually see a hill in there but almost looks like it is pulling timing or something. I'm sure speedinc would have caught that though.

Air fuel looks about right.

And the obligatory - go see how it runs. Dyno numbers, especially on a stalled auto, don't tell the whole story.

429firehawk

1 3/4" primarys on the QTP's. i did not get a log of the pulls i will ask for one. it drives and runs well. the car comes on hard as you would expect with the stall but is pretty violent when it does.

429firehawk

no dice on the data logs he said he has deleted them

jimbob

iTrader: (4)

CUT-OUT ? I know my 427 with a 4l80e tranny goes from (converter locked) of 584SAE down to 544SAE when my 4 inch Cut out is closed. I use a necked down 4 inch to 3 inch (smooth transition). That then goes thru a Dual/Dual. 40 Hp is a rather large loss.... I am using cats So the loss might even be higher with the catted Y-pipe out of the way. Just food for thought if your not using a cut-out....

429firehawk

im thinking of dropping the exhaust before the axle right after my y pipe merges. installing some sort of shorty muffler and a turn down. the exhaust drops to 3 inch before the magnaflow muffler as it goes over the axle. that would be nice if were my main problem. im afraid the neighbors wont like that setup but

jimbob

iTrader: (4)

**** the neighbors I bet your down 20--30 SAE with no cutout. When my combo was a 12 to 1 (with e85), I put down 543 SAE after tuning. Shaved heads to 13.7, installed 4 inch cutout vice 3 inch cutout, flowmaster y-pipe instead of ARH y-pipe. A little tweaking and 584 was my last dyno. I'm now expecting over 600 with higher flowing cats and vacuum pump. It's about making sure your combo is tweaked to an inch of it's life. There's lots more there for ya....

oops..... almost forgot, I also found some hp in a FAST LS7 manifold miss-match to my MAST LS7 heads, along with a much better port job by LS2 portworks (over another company who originally did it). I'm sure that miss-match (a tenth of an inch of the manifold was blocked by the bottom of the head...not good flow) and clean ported manifold could account for another 10-15 (in my case).

429firehawk

thanks jimbob i will dump the magnaflow and see how it does next trip to the dyno.

Speed inc. says their best guess is my valve springs are not strong enough or my cam is indexed wrong. valve springs are the ones that came with the heads and should be sufficient but you never know.

im gonna try all the other options first before i open up the engine i dont feel like taking the motor apart right now its just starting to get warm here. LOL

jimbob

iTrader: (4)

Yeah, I did note your rpm for peak power is pretty low with that size cam. And, yes valves that bounce on the seat can cause loss everywhere when not propery controlled...

Brian Tooley Racing

iTrader: (13)

My 427 with 235's and a 90mm TB and 3" piping was pulling down to 93 KPA manifold pressure.

My 454 with 245's and a Fast 102/NW102 and 4" piping went 99 KPA on the dyno and 101 KPA going down the road.

Ditch the 92 and get a 102 with a minimum of 4" inlet.

33 degrees of overlap is too much for a 102, let alone a 92, in my opinion your cam is wrong. I made 599 rwhp with less overlap than that.

You need 1 7/8" headers.

The TFS 235's don't match the Fast 102 worth a hoot, the heads need to be pulled and a Fast 102 port matched to them. Material has to come off the intake port on the heads to make them right.

The engine has flat top pistons? The torque is low, almost looks like the compression is low?

Do a leakdown and compression check on the engine.

Maybe ditch those injectors too, I used FMS 42 lb/hr injectors at 58psi and had 85% IDC.

I hope this helps.

429firehawk

Sounds like i need to take it apart and see whats going on. Definetly sounds like i have some intake an exhaust restrictions for this setup. Im gonna do a leak down and check the valve springs as well. Who is the best cam guru that could recommend a better cam for this setup once i change to a 102 and 1 7/8 headers? Thanks for all the help guys.

429firehawk

Found problem transmission was slipping in third under power. Thanks for the help guys i appreciate it.

MikeG

iTrader: (33)

New numbers?

429firehawk

no numbers yet. hopefully taking it to the transmission shop next week for a rebuild and then i will get it strapped back down again. hoping for 550 rwhp which shouldnt be too far out of the park being that it was slipping at 6k before.

now to find 3 grand laying around.