New best for thw Silver GN

[forcefed3.8's]

Went out to Dragway 42 last night trying to get the silver slug in the 10's. Right off the trailer, it wet 11.06@123.61 with a 1.61 60' launching with 5psi.
I had fixed an exhaust leak, and activated the launch assist in my extender chip. I figured it would come out harder than that. It seems like the launch assist makes it leave softer, but is easier to build boost wothout the car creeping. I tried 2 runs with no launch assist, the first was with 10 psi, and it spun badly, the second was with 5 psi, and it spun when boost came in afew feet out.
I am trying to figure out where my mph went. Last year, the car ran 125 on 22psi. I was running 25 last night. My O2's were around .760 the whole way down, and the car ran good. Last year, I had leaking steal shim headgaskets that made the car cut out at the top of 1st and 2nd. Last year, I went 11.10@125 with a 1.56 60'. It had a quicker 60', more trap speed, but a slower ET because of the popping. I am running stock headgaskets now, with pushrods that are giving .050 preload. Is the preload costing me HP?

 

[Chris McDade]

I don't think the preload is your problem. How tight is your convertor? How are you tunning the car? Do you have a wideband 02?

 

[forcefed3.8's]

I am running a 3200 stall precision. I am just using a scanmaster. Next on the list is a wideband. Going through the traps I am seeing about 5800 rpms according to the Scanmaster. This is with the converter unlocked and 28" tires.

 

[GNVYUS 1]

It looks like if your converter was 100% you should have trapped around 5100 rpm so you might need to look into tightening it up.

 

[Chris McDade]

Well, if he's running a 28" tall tire and going through the traps @ 5800rpm that sound about right to me. If, it's in drive not overdrive. You don't want to be going through the traps @ 5100rpm, becuase your out of you power band.

Your 60ft's are killing you. You should be low 1.5's or high 1.4's. You have the mph to run 10's if you 60ft where there. I would say get a wide band and turn up the boost. Your heads/intake could be restricting air flow and not allowing you to run higher mph. Im not 100% sure.

Hope this helps.

 

[forcefed3.8's]

I tried to get it to 60', but the track wasn't prepped well, it was street car night. I am just baffled on the MPH, it went 125 last year at the same track, with 3 less lbs of boost, and a popping problem. The only difference this year is new headgaskets, and pushrods. I added a single shot exhaust, but upcapped it at the track, maybe I will try removing the dump. The car was running hot. I think sitting on the line with the launch assist heated it up, and the car never got the chance to cool down. It would go down to 180, then would be back up to 200 after the burnout. I have never had cooling issues before. I have the fan set to come on at 165 now, and gave it some more timing in 1st and 2nd, so hopefully it will pick up next time out. I know it will go 10's with traction, I was just worrying about the mph loss. When I ran it last year, it was cooler out too, but I figured more boost would make up for it. I am happy with the way the car is running, that was only the 3rd time out with it, the whole car only has 200 miles and 13 passes on it since I redid it. I am just happy the popping problem is gone, and I fixed the slow spool exhaust leak it had at Norwalk. I just want to go 10's. After it goes 10's, it is getting turned down to 18psi until BG and Norwalk.

 

[Chris McDade]

Im assuming your running strait race gas. What's your timming?

You running slick? What's your suppension like?

 

[forcefed3.8's]

I am running 275/60 MT ET street radials with about 19psi in them, 1 3/8 ATR bar, poly bushings, pass air bag, and UMI tubular lowers. The car went 1.56 launching on 7psi last year with the leaking headgaskets. I think it was just track prep. I have an extender chip, and 1st and 2nd gear timing can be adjusted up to 4° advanced, and since I saw 0 knock I figured I would try some more timing next time out. It is a 104 octane chip, so I figure it isn't too agressive. I am going to try to get in on a track rental, so I have all day to mess with it. I only had 2 hours the other night after I got there after work.

 

[GNVYUS 1]

My point is that your torque converter is slipping about 13%, that's not great and most people say 6% at most and some with the 5 disc are getting %100.

Check it out for yourself.

:: Torque Converter Slippage Calculator

 

[forcefed3.8's]

I am not putting much faith in those numbers. I had the scanmaster on rpm's to see where it shifted, and as an after thought, I glanced at it right before I let off, which is always after the traps. I might have been going 128 when I let off, I don't know. I am gaining 26.5mph in the last 1/8, which is about right.

 

[Chris McDade]

What is your total timming 24 or 26 degree's? It's very important to know.

In my opinion, if your happy with low 11's then leave the car the way it is. If you really want a 10 sec car then get a pair of slicks and quit messing around with those other tires. You have to have your suppension just right to run any type of radial tire and that cost allot of money.

On my car I had a 3400 stall convetor with a 66mm turbo and I had to leave with about 15-18lbs boost to get the car to go 1.4's 60fts.

What turbo are you running? Where is the sweet spot on the turbo? It could be at hight boost range.

 

[forcefed3.8's]

It is a TE63E. I am running 25° in low gears and 23° in high gear.

 

[Chris McDade]

With strait C16 I would run 26 degrees of total timing. You need to get a wide band 02. IMO it's the best way to tune one of these cars. It might not be the parts on the car thats keeping it from it's fullist potional, it could be the tune. Get the tune right first and then go from there.