Went to the track to get some testing done. Car performed very well or at least I thought. It's a simple 5.3/SS2 cam/billet s480/4l80 setup. It has a 3.55 gear with 255/60 MT drag radials. I'm running e85 and controlling it with MS3.

The details of the run in question:
1.40 60'
[email protected] 660
[email protected] 1320

I'm launching at 3300 rpm with 12psi and 20*. Converter flashes or couples at 5488rpms. It picks up the driver's side front like a G Body for at least 60'. Leaves hard.

Boost fluctuates with each gear. Spikes at the gear change and proceed fall off as I go through each gear. Not by much. Maybe a 1-3psi. 3rd gear has the least amount of drop. Converter drop on the gear change is 1400 rpm (1/2) and 1500 rpm (2/3).

Stats at the end of the pass:
17.7psi @ 18.4*
AFR 11.1
6176 rpms
IAT 152.5* (not pulling timing)

This is my first time at this power level, ET and trap speed. I've had more than one person say that I should be trapping more. I tend to agree as the car feel lazy from 3rd to the end of the pass. Just looking for some feedback and possibilities as far as falling on it's face up top.

Thanks



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What do the plugs look like? I've never tuned e85,but isn't 11.1 lean at 17psi?

 

No. Tuning to gas scale is normal.

 

The plugs looked fine. Number 8 was showing just a slight bit of "pepper" telling me I might be at my limit for timing on that cylinder.

 

Converter locking up?

Converter Slippage?

With a 4l80e 3rd gear of 1.00:1 ratio, using 3.55 gears and 255/60s @ 6176rpms it should be right around 140mph.

 

It's a nonlockup converter. I've never experienced a loose converter, but could imagine it's like holding in the clutch a bit.

 

What plugs and gap?

 

Math worked out to 5% slip with numbers provided.

 

Thanks for doing the math. Glad to see it's acceptable.

The BR7s are box stock. I don't gap them, but inspect them to make they don't have Grand Canyons for gaps. I'm not sure if I'd feel the spark blowing out, but one would think if it feels like a miss. I've talked a few people about the nonlockup and the only guy that has one is running almost the exact same numbers.

I appreciate the input. Keep it coming.

 

What springs?

 

BTR 660s

 

Gap the plugs to 0.018" and report back. Gaps being too wide will not feel like a miss, it is more like a high rpm loss of power. You have the most load in high gear, so that is where it really shows itself.

 

I'll do it. Hopefully I'll be able to test on Friday.

 

I haven't been able to make the track lately. Found out my tires were showing cords. Not good. While waiting on new shoes, I checked the gaps of the BR7s in the engine and all of them had a gap of .025". I took them all down to .020" I'm supposed to get to the track this Friday or Saturday.

 

Well, the outing didn't go nearly as I hoped. Too many new parts and the car just didn't work. New, shorter downpipe gave me a lot less restriction resulting in 4-5psi more at the same dc on the controller. The new ARB helped it leave straight, but clearly upset the rest of the suspension. I have some plotting and suspension work to do now. To be continued.

 

I think the extra 4-5psi with the open DP is a great sign that you've fixed the 3rd gear power issue. I told't you the exhaust was too small!

 

Any updates on this problem? I ran to the same problem on my last track outing and can't seem to figure it out. Set up is SBF 302 stock bottom end, AFR 185 heads, F cam, 78/75 On3 Turbo, 4R70w MVB with brake, and a TCT converter spec for a 4V twin turbo car (not ideal, but using what is at hand). At first I thought it was the converter, but reviewing the datalogs I think it might be tuning wise. Either is not carrying over the power, losing spark, too lean (had wideband sensors go bad).... but sorry to hijack your thread, just looking around to see your results. Best of luck.

 

Start a thread and put up some info,I'm curious.

 

Yeah, it's doing the same thing. Got a personal best the last time out to an 1/8 mile track. Installed a 4 port Mac valve and I'm going to play with the boost control duty cycle a bit. Would be better served to turn on my closed loop boost control I'm sure. I'm not really sure where to start with it. #ad