Pumpgas GSR w/ T67, 429wtp/303wtq

Joey Misanthropy · Post by **Joey Misanthropy** » Sat Dec 01, 2007 7:14 pm

I tuned this car to wastegate last week, finally got back to it this Thursday to tune higher boost. 11-12 psi wastegate pull:

I started having problems with ignition misfires at 16 psi/385 whp which were only partially corrected by tightening plug gap and later replacing the coil. Power was really down as I cranked the boost up despite the plugs looking clean. I'm not entirely happy with the ignition wiring on the car, and there might be some issues there. Here's 22 psi:

xenocron · Post by **xenocron** » Sat Dec 01, 2007 7:46 pm

Let me guess...stock head. What a powerband!

When you see the power per lb of boost ratio start to decrease as you up the boost on a turbo setup like this, when do you generally attribute it to? I find it incredibly frustrating...wish I would have taken more engineering classes when I went to college

Joey Misanthropy · Post by **Joey Misanthropy** » Sat Dec 01, 2007 8:35 pm

I believe it has valvetrain, but the ports/cams are stock. So are Goforth's, among others, so I don't see that as being the problem with what should have been an easy 425 whp tune. I've tuned a couple 90-91 LS head (wimpy plus probably automatic cams) engines that make piss for power... 250 by 14 psi, 290 by 19, etc. I've seen 297 @ 12 psi off unported LS with \"402T\" cams on Mustang dynos, so mileage varies. Different heads, but IMO illustrates the bottle neck you're talking about pretty well. Starting at the ~14 psi 370 whp level this car was nothing but trouble with constant misfires 6500 to redline. Even after swapping/gapping plugs, checking plug wire resistance, replacing the toasted and partially melted rotor button it would only do consistent 385-386 at 16 psi with one 393 at that pressure after letting the engine cool. Replacing the Blaster SS coil (no MSD box tho) got us to 429 @ 22 psi and despite the plugs looking clean I pulled the plug on taking it further. After 12 psi the RPM vs MAP vs AFR chart never laid a slick smooth AFR line down like I'm used to seeing. Meh.

sewell94 · Post by **sewell94** » Sun Dec 02, 2007 3:27 am

Weird, 10 lbs more only netted 60hp, thats odd for a 67, that thing should be starting to pick up crazy, but it made a ton on the Wg though. What manifold and hot side on the snail??? That thing should be a blast on the street

Joey Misanthropy · Post by **Joey Misanthropy** » Sun Dec 02, 2007 3:35 am

It's a Peakboost kit, complete down to the undercut ramhorn that'll have to be fixed within 6 months.

sewell94 · Post by **sewell94** » Mon Dec 03, 2007 4:36 am

I need to learn how to make my graphs all nice and pretty like yours, Mine look boring as hell,

BRMS · Post by **BRMS** » Mon Dec 03, 2007 11:56 am

Joey Misanthropy wrote:It's a Peakboost kit, complete down to the undercut ramhorn that'll have to be fixed within 6 months.

And Yes, its a blast to drive on the street!!^

sewell94 wrote:I need to learn how to make my graphs all nice and pretty like yours, Mine look boring as hell,

Thanks - I like how our dyno displays the graphs /w our logo and all (after i photochop it in)

I just wish the software was a little better....

Joey Misanthropy · Post by **Joey Misanthropy** » Tue Dec 04, 2007 11:57 pm

Brandon, tell Cole he owes me a ride in his car.

sewell94 wrote:I need to learn how to make my graphs all nice and pretty like yours, Mine look boring as hell,

I can turn the shading off if the colors - especially the pink 429 whp graph - make you feel inadequate as a man.

sewell94 · Post by **sewell94** » Wed Dec 05, 2007 2:28 am

Ya i feel like I like i'm running around naked and its 20 below outside, so ya i you make feel inadequate as a man