spicebird98

iTrader: (10)

About 6 months ago I sold my bolt on 01 z28 which rana best of 12.42 @ 113 in 700' DA while I had it. The new owner made some modifications and wanted me to make some baseline runs for him.

New mods:
230/238 ~.600 111 BTR cam, Btr springs, PR's, etc
Circle D 3200 nitrous stall converter
Mickey drag radial et streets 275/50/15 on pro stars

Car made 370 rwhp ~ 6000 rpm haven't seen dyno sheet just what I was told.

So we ran is this weekend at 1000' DA and managed back to back 12.296 at 111 and 112 respectively. 60' went from 1.88 when was just boltons to 1.79
Now with current setup. From what it looks like ET and speed only show the addition of the converter with NO gain from the cam. The 8 hundredths gain in 60' work out to 16 hundreths on the big end in theory which puts us right at 12.30. Any idea what the issue is here??? Tune seems to be spot on by the back to back Passes. Tuner seems to think its the stock MAF holding it back or the exhaust setup( bbk mid lengths, Catted Y, hooker aero chamber)

I'm thinking it has more to do with the gearing (3.42's) and inefficiency of the converter Not being able to utilize the higher RPM range of the cam, but still think it should've picked up considerably more. Time slips attached. Any input guys?

scotty2000ss

iTrader: (2)

Gears will help lower the ET but won't the mph go down or at least stay the same? I agree the stock maf is leaving some on the table. What's KPA at WOT?

spicebird98

iTrader: (10)

No idea what kind of vacuum it's pulling. I was basically just there to run the car. I'll have to get more details from the tuner. I agree that the MAfF is leaving some on the table, but still wouldn't think it would show zero gain from what it was before. I would think a set of 390's would be good for 1-3 mph.

scotty2000ss

iTrader: (2)

What was the old set up? What did it dyno?

spicebird98

iTrader: (10)

Old setup was stock internal, stock stall, bbk headers, Catted y, hooker aero chamber, slp lid, super sucker ram air, 3.42's, toyo tq 255 on stock wheels. Never dynoed it, only had it street tuned. Only changes were those mentioned, but was consistant 112-113 at stock weight. Also maybe thinking the new converter is just that inefficient.

scotty2000ss

iTrader: (2)

That's too bad that it didn't gain anything with the cam swap. I know this isn't a good comparison but my car trapped low as **** till I added a 92/92 and CHRS 1313. I picked up a solid 5mph from it. Point being the added air flow really woke the car up. Picked up almost 30/20 on the dyno.

spicebird98

iTrader: (10)

I definitely agree, more air equals more power. Just a shame there's been such little gain. The car was fast for what it was before and is still deadly consistent

murphinator

iTrader: (2)

agree the convertor is the only thing saving it even though it is conservative and likely tight since its a nitrous convertor. The trap dropped with adding a cam - it lost power plain and simple traps show power. It also looks like he went to a taller tire than you had another factor in not letting it get into that cammed powerband as easily , I assume its being setup to run spray though with keeping the 342's ,taller tire , tight convertor so on spray is where you would expect it to shine - the na setup got worse other than the convertor helping 60 a bit.... I remember the posts when you were racing the car a few years ago you got it to do a lot with a little he is lucky to have your input.

typedRew

I'd bet the cam is in the wrong part of the power for the shift point, gears and the converter is too tight.

- Drew

spicebird98

iTrader: (10)

Shift points are both at 6200

typedRew

And where is the power? Has the car been dyno'd?

What's the shift extension? Is it dropping too far out of power between shifts?

I'd really just put money it being too tight for the NA setup. I'd up the converter speed before messing with gears.

- Drew

spicebird98

iTrader: (10)

Made 370 rwhp just after 6000 rpm. Fall back was around 1200 rpm's. Obviously it would be much better if it was in the 500-800 range. There's no doubt it's too tight for an NA setup, the combination was supposed to retain good drivability, which it does. Werent looking to set the world on fire with the 1/4 mile times, just think it should have picked up more from the previous setup, that's all that this thread is about.

guppymech

iTrader: (7)

You probably should set your shift points higher. Check out this info by quick95lt1.
https://ls1tech.com/forums/drag-raci...l#post16001189

bjamick

iTrader: (31)

Yep it's most likely the converter/shift rpms. I would think that cam prob peaks around 6400 rpm shift it around 6800 or so. Also no need for a fast 92 setup. My old ls6/pp tb trapped 117 on my nitrous tune 24* timing.

Mazzenger

iTrader: (5)

Some doesnt' seem right.
When I put a little 221/221 and SY3500 stall in my 98, it dropped .6 tenths and gained 3-4 mph in the traps.

I know all cars are different and set-ups are too, but I would think there would more of a gain for that set-up.

curtisrp

iTrader: (3)

I went from a 3.23 to a 3.90 gear. I only picked up .04 ET and .59 MPH. I don't understand what happen, LOL.

kinglt-1

iTrader: (26)

Shifting a 230/238 cam at 6200 rpm is the problem. Bare minimum should be 6500 and 6800 would be even better.

big hammer

Converter is too tight too.

Kingc8r

iTrader: (21)

I agree.

All good points.

Good info.

Yup gears don't do as much in autos. There are many people who have noticed a .10 or less once an aftermarket converter is involed in the equation.

That's what I'm thinking too.

Yea minimum is a 3600 and even that's too small. I know I got a 3600 and wished I got a 4000+ immediately.

thunderstruck507

iTrader: (18)

This is your primary problem. That cam will want to shift at no less than 6600rpms. If the converter is overly tight or the car is overtired/under geared shoot for 6700/6800rpm shifts. My roommate had it in a M6 and was trapping 112 due to under revving it and shifting around 6-6200.

I had a 230/238 113+2 in a ls1 auto trapping 113 in bad air and 116 in good air shifting at 6700rpm. This is in a car that weighs more and has less aero than a fbody (I did have 799 heads to help).

The converter is too tight. My SS3600 was obviously holding me back as evidenced by my 1.72 60ft dead hooking. It would have really liked a SS4000 converter.


The other thing is the exhaust. The exhaust duration will help cover it, but it still desperately needs longtube headers and at minimum catless 3" into single 3.5" or 4" I pipe.