TD Ben's Twin GTP Engine nascar making many 8 second passes

twinv6gtp

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Lowered the boost to save the transmissions.
Enjoyed many 8.6 passes @ 162 mph. Pretty consistent.
Upped the boost on the last pass and ran 8.5 but backed off at 900 feet. Data says it should have been 8.3x or 8.4 low.
All in all pretty happy with the car. Track was too slippery to add any more boost. That's why I backed off on the last pass, I was spinning all four all the way down the track. The first 300 feet hooked hard but then it was all over.
Almost clipped the beams at the end lol.

http://www.youtube.com/watch?v=XzwTJi6rTl0
 

Turbocharged400sbc

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whats your toe set at?

the way that steering is acting its like your at a toe out condition. dial in another degree of toe up front. took three 1/2 turns on the TR before it started to want to go straight under power. nearly 3* of toe but it went straight, id also say that it likely helped minimize the scrub on the inner half of the slick. now that we have the zzp lca's im sure we wont need as much but im figuring on it being a possibility I gotta hit it up a single turn for the track.

you ever hookup the rear pcm to the trans sensors so you can datalog the 80e slip/gear ratio calcs?

on a street car id change it back but since its a track car...you could set it and forget
 

Turbocharged400sbc

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the main reason I really believe you have a toe out issue is with those adaptors and rims you now must have a crapload of positive scrub radius. to help twist em even more towards a toe in condition.

this was one of the things to fix with the 442's suspension but well worth the effort
 

Bru

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Are you battling a mechanical grip problem, or is the track prep just garbage?
 

twinv6gtp

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Its strange and not quite right. But under power when traction is perfect it does go straight. When letting off it goes straight too.
But it very easy to destabilize with minute steering input. Also if i go out of traction groove car will the direction i went off. It always tends to sway side to side in the rear. Not much but you can feel it.
 

twinv6gtp

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Tire wear is worse at inner part of the slick indicating a lot of scrub.
 

RICH17

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Seriously. This thing needs to do Hot Rod Drag Week
 

twinv6gtp

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Are you battling a mechanical grip problem, or is the track prep just garbage?
Both. At a good trac id have zero traction issue imo. But i could improve my traction to hook better.

The pro mods here can never hook well. They take off and dont run at full power.
And they have massive slicks.
 

Turbocharged400sbc

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Inner scrub....Yea dude...seriously dial in more toe. The TR tracked like a dream when I cranked the tie rods 1 1/2 turns out each side with the oem LCA's.

Might help clear up that rear wiggle too if that end is toe'n out as well. the Outback you'd probably do better to put the tie rod end parallel and at the same length as the lower control arm to minimize the OEM bump steer
 

twinv6gtp

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This thing is just so awesome!!!! Congrats on those numbers. 7's not far off.
It ran an 8.2 once so far (No timeslip they timed only 1/8 mile) but at much higher power level and was not a full run. Ran 5.31 @ 138 mph in the 1/8 mile.
With better launch technique and that high MPH it can do 7s no problem.
But to run 7s I'll need to be at very high boost and our track in great conditions.
 

twinv6gtp

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Inner scrub....Yea dude...seriously dial in more toe. The TR tracked like a dream when I cranked the tie rods 1 1/2 turns out each side with the oem LCA's.

Might help clear up that rear wiggle too if that end is toe'n out as well. the Outback you'd probably do better to put the tie rod end parallel and at the same length as the lower control arm to minimize the OEM bump steer
I'm dialed in for 0.3 toe in in front and back.
But under power I bet the tires toe out...

Too much too in can do funky stuff too. Not as bad as toe out.
I might try a little more toe in like you said...

For the tie rod I did make it more parallel than stock. Tried many locations.
RIght now it's best it's been. But it's still not quite right and has some bump steer. I need to put all of this info in a suspension engineering software and precisely calculate the right location.
 

Turbocharged400sbc

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Ah...then you'll feel the headaches I had with the 442's first suspension iteration with struts.
The TR had visible toe in and didn't try to squirm under braking at the top end. ...and that should result in a max toe in situation.
Where is it scrubbing around on those slicks? (Swirl center from a stationary lock to lock turn)
 

twinv6gtp

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Ah...then you'll feel the headaches I had with the 442's first suspension iteration with struts.
The TR had visible toe in and didn't try to squirm under braking at the top end. ...and that should result in a max toe in situation.
Where is it scrubbing around on those slicks? (Swirl center from a stationary lock to lock turn)
I'll take a pic
 

twinv6gtp

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uploadfromtaptalk1443457289963.jpguploadfromtaptalk1443457298390.jpg

Three have inside scrub. 1 has both inside and outside. This weekend i paid no attention to tire pressure as i was focused at fixing the maf and boost leak issues i had.
 

Turbocharged400sbc

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and for scrub radius I was referring to the point at which the tire pivots around when you turn it lock to lock on the ground and then roll the car forward and measure the center of the pivot
my guess is that you have at least one inch more positive scrub radius than a stock tire and rim
 

twinv6gtp

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My stock MAF were really limiting my Max HP tuning. Since I had to dump so much fuel it killed my spool up.

Upgrade to the LS2 MAF and a 4" tube. Testing so far shows it reads a little more airflow. 20 psi at high rpm it's maxed out signal wise (Hz).
May still need a translator...

Before with the stocker it maxed out right at around 15-17 psi without a MAF translator.

Put a pressure gauge on both trans with low and high warning lights. Rear 4t80e (stock) runs 210-220psi in drive around 270-280 in reverse.
Front 4t65e-HD with Dave's valve body around 340-380psi !!

http://www.youtube.com/watch?v=CVYyUJOWMGg
 

twinv6gtp

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[email protected] today and let iff for a sec at 200 feet (tire shake)

@ 24 psi

Then almost lost my flexplate on rear engine... rattle. Red lock tite arp bolts loosened...

Fixed that in the trailer with my mechanic. Seperated 4t80e with engine...

But two bolts broke in crank... will try with two bolts less...

Going for 29 psi tomorrow.
 

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