1989GTATransAm

iTrader: (3)

OK, just got back from the Los Angeles Invasion. I got a best of 11.572 @ 115.73. It took me until the last run to get the hang of my latest setup. Here is the time slip.

JulieGTA

(Oops! I'll delete my post and put it here.)

Allen did great! A lot of people did.
I did OK, still in the 13's but maybe a new best. I need to look up my old times...

13.125 at 104 mph

(previous best was 13.29 at 102 in 2009)

Dyno Don

iTrader: (7)

I also got a new best.....

12.45 @ 110.71

Z28FAST1

1st pass, lost clutch pedal pressure after the burnout, missed 2nd and 3rd = 13.xx@105

2nd pass, clutch sticking to the floor/granny shift = 12.3@115.4.

Found out my master cylinder took a dump its leaking fluid and not holding pressure Should go 117-118mph once I fix it.

PS, congrats to 89GTA for the solid 11second pass. Time to shoot for 10's.

Yahtzee

Best 60ft 1.91
Best E.T 12.79
Best MPH 115

None of which were on the same run lol.

Also got to weigh the car on Sunday.
Came in at a whopping 3270lbs.

skinny z

Nice! You have to be happy with that.

1989GTATransAm

iTrader: (3)

"Nice! You have to be happy with that"

Yes, that was my goal for this meet. With a few tweaks and better air in the Winter up at Formosa race track in Bakersfield I am hoping to close in on a 10.99. A good portion of that will mostly depend on how well my new long tube runner intake does. If I can get a driver that weighs 100 pounds less than me that would help. I figure my race weight is around 3675 pounds.
I weigh 260#.

Yahtzee, you have a lot more left in that car. A 1.6X 60' would help a lot.

skinny z

Excellent 60' for a heavy vehicle (at least I think so anyway).
That was with the ETB's I assume?
I have my first trip to the track in nearly 2 seasons coming up on Saturday. Supposed to be a miserable race day with high temps and high humidity.
Still, I'd like to better my previous best (12.77 @ 105) with this chassis that has more gear, a fresh short block and a few other goodies. Hopefully lighter too.
Congrats again and good luck tracking down 10's. (I'm quietly hoping for an 11 second time slip too however I think that low/mid 12's is more realistic.)

1989GTATransAm

iTrader: (3)

"That was with the ETB's I assume?"

I am having a brain fade. What are ETB's? Quality air really makes a difference. Having hot air and humidity are not going to help things for you.
In do time you will get your 11 second time slip. Every time I think I am done with the car another idea pops up.

skinny z

I wasn't sure if that would catch on. Saying Exhaust Termination Boxes makes it sound so clumsy for such an excellent piece of equipment.
I'm sure that and all of the other upgrades contributed to the 11 second time slip.

VincentZ28

iTrader: (2)

My car went 12.48@112. Still hitting a wall. Don't know what it is.

skinny z

Is it a top end charge? I ask because I'm sort of going through the same thing. WOT AFR's at the top of 1st and 2nd are excellent at 12.5:1.
Same on the chassis dyno.
Once I climb to 5k in 3rd, they drop off until I hit the kill switch before 6k.

1989GTATransAm

iTrader: (3)

Yes, the ETB's are on the car and working quite well.

Dyno Don

iTrader: (7)

I'm having the same problem, when Allen reaches 5200 his tq. is 400 and dropping but his hp is at 400 and going up.

Mine is 400 tq. @ 5200 and starting to fall, hp is 400 and starting to fall also.

I will be looking into maybe a intake turbulence as my runners are different than his.

AFR is ok all the way to 6k.

I had a best of :
1.79 60 ft.
12.45 @ 110.71

Dyno Don

iTrader: (7)

Here is our DATA:

skinny z

Intake tuning is as vital as exhaust tuning (as you know) and there could very well be pressure wave problems causing a disruption in your intake flow as compared to Allen's.
Another thing to consider is the overall effectiveness of the termination boxes that Allen has added to his combination. (I think it's Allen anyway)
Peak torque occurs at maximum cylinder pressure so that is to say also at peak Volumetric Efficiency. The point of the termination box is to increase the VE via pulse tuning. Perhaps the difference lies in that modification too. Since you both run Dyno Don headers (IIRC), if there's any difference in the exhaust it would be in the boxes. Unless of course you run a cork for muffler like I do.
Just thinking out loud. For what it's worth.

Burnout91

12.84 / 106 / 1.88 60' / .012 RT (all new bests), but had a nasty driveline / axle vibration on that pass so I only made the 1 run. Gotta find the vibration prob, and work on the launch with the SS4000, which I believe is a bit loose. I just stalled to about 2500, and shifted ~6000. Might be a little more in it, somewhere...

Congrats to all; seems even with problems most cars were running decent numbers.

Bill

VincentZ28

iTrader: (2)

Fix the vibration. Next time leave at 1200rpm and shift at 6400. That should put you in the low 12's high 11's at 110-113

Yahtzee

Was nice talking to you this weekend, I was parked next to you in the black LS1 IROC. Your car is super clean man!!!

Burnout91

Yes, nice talking to you, also. Shawn / Sean, right? My mind was pre-occuppied with my vibration problem...we should have slapped my DR's on your car for a pass, but I was not sure if the 15" wheels would clear your rear disc brakes.

Bill

Dyno Don

iTrader: (7)

Here is Allen's DATA before the ETB's in '08.
His was doing the same then, hp going up at 5200 not down.

In my opinion, the jury is still out on those, as we have yet to install the pipes made to replace those and then dyno it.

Yahtzee

It's Sean.

****, I wasn't sure if you were serious. I would have loved to make a pass or two with some good tires! Stock rear discs. It's all good, I had fun. BTW have you checked out your pinion angle?

JulieGTA

Hi Yahtzee! You beat me in my last race, fair and square, with the faster car. (Not on video) But I missed 2nd gear!
Nice to meet you, seemed like you guys were LSX serious racers!

mattzoom

heres some third gen pics and yahtzees runs

http://www.streetfire.net/video/camm...ng_2260764.htm

TPI TERR

iTrader: (9)

On Saturday I noticed thatyou werent on the nittos anymore. And I know regular tires didn't help out at all.

skinny z

I appreciate your skepticism. I'd like to see a before and after too.
The effectiveness of the ETB's is limited by the amount of valve overlap. With the wider LCA's of an EFI cam and the restrictions on duration because of your strict emmision requirements, the benefit of the modification will be less pronounced. I would think that there would still be a measurable difference with the testing you've mentioned however I would think that an aggresive cam, with duration approaching 290 advertised and LCA's in the 108 range would really see an advantage. I haven't checked the SoCal sigs in a while but IIRC don't you typically have LCA's in the 112+ range?
Still, I think it's a worthwhile effort and one that exploits the limitations that you guys are forced to deal with everyday.
It's great reading for sure.

Yahtzee

Yea I missed 4th that run too
Yea Nitto's were worn out. But the PS2's actually got me a 1.9 60ft.

1989GTATransAm

iTrader: (3)

Skinny Z you make some good points about the effectiveness of the ETBs. I run a 113 LSA. To help things out I also have a 1.72 rod ratio and this allows for a longer dwell time for the piston at TDC. With the longer dwell time there is less volume for the exhaust gas to pull on so it can do a better job of exhausting the burnt gases and start the pull on the intake charge.

The wider LSA also means the intake lobe is open slightly longer after BDC. With any luck my new long tube runner intake utilizing the second harmonic wave will be able to continue filling the cylinder after BDC until the intake valve closes. Hopefully this will greatly increase my VE. At least that is the plan.

One more thing is that the AFR heads have good low lift flow characteristics. This helps things along during the overlap period and after BDC as the valves are opening and closing.

slow91camaro

A bit late but 12.69 @ 106.95 on pump gas with 11:1 compression. MPH was down a bit from last two trips(109-112) with better air so I think it could have gone a bit faster with good fuel.