redtan

iTrader: (5)

Went to the track the other day after finishing off a bunch of mods and tuning for them (ported 243s, small cam, FAST 102) and did not get the results as expected.

Prior to those 3 mods the best time slip was as follows:

1.9 sixty
8.4 1/8
87mph
12.9 1/4
111mph

Now with better tires and more power I only got:

1.9 sixty
7.9 1/8
90mph
12.4
113mph

Car is an LS2 weighing in at 3700lb, 4L60E with a 2800 stall and 3.46 gears. Run was clean with no wheelspin or bog off the line, log showed full timing with no knock, mid 12s AFR and shifts right around 65-6600.

1/8th mile results are good, dropped half a second and 3mph just there. But none of those gains carried over to the 2nd half as the gain there was still only half a second and only 2mph more. With just bolt-ons I picked up 24mph on the back half and with all of these mods only 23...

DA and weather were in fact better this time around also as I've rarely seen such cool weather at the track in the middle of the summer.

Any thoughts?

zracer323

iTrader: (12)

I would start with the basics: plugs, wires, fuel filter, maf, etc.
what fuel pump are you running? have you logged injector duty cycle? Also look at your 660-1000 and 1000-1320 splits. You may be running out of fuel on the top end.

murphinator

iTrader: (2)

needs bigger stall to match fact it is now cammed ???

redtan

iTrader: (5)

Plugs and wires have less than 5k miles and there is no MAF. Fuel filter is part of the stock fuel pump, which I was told is enough. Injector duty is below 70% as I have recently added some LS3 injectors to the mix. As I mentioned, AFRs were good (low-mid 12s depending on gear) throughout the run.

Cam is relatively small for a 364, it's a 223/227 112+2. I imagine a bigger stall would help, especially out of the hole and ET but wasn't aware that a bigger stall like 36-4000 would help with the top end.

Car runs good and is in good mechanical condition, just doesn't seem to be making the power uptop to pull better traps. I know the cam isn't big, but I still figured with that, ported heads and a FAST I would gain more than 2mph. Maybe the lower ETs doesn't allow for a big trap, like if I only pulled 12.9 I would trap higher?

Mystery Bird

iTrader: (7)

I'd say picking up 1/2 a second is a good gain. I agree you need a bigger stall now and it would allow you to get into and stay in the power band quicker. Also, the DA needs to be factored in, that can be a big factor. My car slows down a good three tenths in the summer heat compared to spring and fall.

zracer323

iTrader: (12)

Do you have your 1000' time and mph?

thunderstruck507

iTrader: (18)

Looks like the car doesn't like the small converter. 1.9 60ft is extremely lazy.

Who ported the heads? Have your dynoed the engine (to see the power curve)?

When I tune my afr the car will be pig rich in 3rd gear if I tune based on 1st or 2nd gear wideband readings. I try to mostly tune based off 3rd gear pulls and get that dialed in to 12.6-12.8. This makes the wideband read in the 13s during 1st and 2nd which I've been told is fairly normal and the car runs nearly a tenth and MPH faster.

With such a small stall you are losing shift extension, it would be nice if you had a dyno graph to see the power curve around peak. It would likely be faster if you can shift later so it falls to a better power point.

What was the DA?

Your car is one of the first on here that seems to behave like mine. I can trap 93-95mph in the 1/8th but only 112-114mph in the 1/4. The fbodies on here typically trap about like yours in the 1/8th but then get closer to 115 in the 1/4. The ones trapping as high as me in the 1/8th seem to run close to 118mph 1/4.

mkvamso

iTrader: (2)

It looks like it's in a gto
A lot closer to your car in weight and aero than an fbody

That being said 113 trap in a head cam fast gto is still pretty slow, do you have any logs of it at the track?

thunderstruck507

iTrader: (18)

I would be much less worried if it's in a GTO. I just assumed it was a ls2 swapped full weight fbody. GTO makes much more sense.

DA and the small stall alone are probably enough to account for it. 1.9 60ft is atrocious and a good sign the car is not getting anywhere close to it's power band. Also when you say that the car weighs 3700, is that with you in it or out of it?

Mine weighs close to 3700 with me and a full tank. If you weigh a couple hundred lbs on top of the cars 3700, there's some more of it.

You're in the ballpark, just a matter of sorting the combo. Not bad for a first outing at all IMO.

BOLO

iTrader: (40)

The stall is definitely too small as mentioned. I've seen similar mods in addition of a 4000 stall and 3.73 gearing running low to mid 11's @121-122 mph, full weight.

redtan

iTrader: (5)

I do, this is the best run of the day (12.4 @ 113) and I actually got to full throttle by like 11mph, something that I didn't think I'd do. It's a bit too large to upload tho so if you want to take a look at it I can PM it to you or something.

The DA was in the mid 300s so I don't think that was bad, and yes it's 37xx without me and half a tank of gas.

Seems most of you are going with the small stall as being the issue, which I was told it was ok for the small cam. I was always under the impression that a bigger stall would help mostly with the 60 foot and first 1/8th and then fall off on the big end due to less efficiency. Which is why I went with a smaller tighter stall cuz I didn't care so much about the ET and stuff just wanted some nice top end.

thunderstruck507

iTrader: (18)

If someone told you that stall was "ok" for the cam, they must have been addressing the fact it is large enough to prevent pushing through the brakes and things of drivability nature as that is the only justification for staying so low on rpm rating.

A higher stall converter will make it harder to stick on crap tires and in town MPG will suffer some. But the 60ft will gain much more and from there it depends on the converter's efficiency and how the shift extension puts the car into it's power band as to how it will MPH. For instance, Yank has several lines of converters and there might be a 3600 stall speed version of each...the difference being how "tight" it feels and how efficient it is on the top end.

There is simply more to converters than stall rating. I don't understand all of it by any means. But a 1.9 60ft is holding you back big time. Whether or not a converter would help your trap speed depends on the converter efficiency and also what it does to your shift extension points.

This example comes to mind: https://ls1tech.com/forums/automatic...00-ss4000.html

jblankenship

iTrader: (5)

Yes, a larger stall will keep you in a higher rpm band. I say 4400 stall. I like PTC. Bet you
will run 11s then.

murphinator

iTrader: (2)

A quality high stall will give you momentum that continues long after the 60 foot as mentioned the shift extension will be better - it will not drop as far in rpm upon shift putting it higher into the useable powerband in each gear.

If you are concerned with losing efficiency up top then spend the extra for a billet multi disk convertor you can lock up at wot and you will be MORE efficient up top.

Theres a post in the trans section from this spring where a member was able to pick up over 50 whp and 75wtq with no other changes but locking his convertor at wot , granted it was a boosted build but theres many other posts with a couple mph picked up locked vs unlocked same setup/convertor heres the thread :

https://ls1tech.com/forums/automatic...converter.html

Kingc8r

iTrader: (21)

I agree you need a bigger stall. Even my SS3600 seemed lacking. I bet your shift extension isn't that great and it's not keeping you in your powerband since all the other potential issues have been addressed and ruled out. That smal of a stall is a waste unless you want stock mpgs in city.....

mkvamso

iTrader: (2)

Still seems a little off regardless of the small converter.
My car has a 2800 and I ran a 12.1 @ 114 my first pass last weekend with the same 60 foot and a much higher da.
My car is supercharged, but it was hot as hell after the heat exchanger pump came unplugged. I know it's kind of an apples to oranges comparison but a car with similar weight, 60 foot, and mph, in better air, still running slower?

murphinator

iTrader: (2)

supercharged make a ton of torque at low rpm's , having come from SC 3800V6 fwd cars I figured out pretty quickly when I got my first LS1 car (m6 car with most bolt ons) it needed to be spinning some rpm's if I wanted to boil the tires at a 30 roll , first time I tried to do my typical rolling burnout leaving my buddies shop was a bogging embarrassing event lol- my bolt on 3800 cars would go up in an instant ball of smoke in the same situation (11.95@111 4th gen , 12.1 @117 4 door gtp)

mkvamso

iTrader: (2)

Thats front wheel drive, it won't have the same 60 foot and that should explain the mph difference.
At the same trap speed with the same 60 foot in the same car, the et should be pretty much the same minus the difference in Da. My car makes more power, and definitely more torque, but from a to b we got there at the same mph and left at the same rate, just doesn't quite add up

Forcefed86

iTrader: (4)

Are you sure your not floating valves? Its odd to see a 3mph gain in the 1/8th (which I think is pretty good) then have the car fall flat out the back.

Have you calculated your slippage with your current converter?

Changing the launch stall to a higher slip isn't going to give you more trap speed in the 1/4. But if your current unit is slipping or just not coupling well up top switching over to a unit designed to couple hard lower RPM will make a huge improvement. I went from 15% slippage to 4.8% up top. BIG difference.

ejbta2

Get a 3600 stall, better stall better time. I run a yank ss4000 1.62 60'. get your 60 down to get your time down. A ss3600 would get you about 1.7 60'. I would pick something in mid 3000's. My son runs a ss3600 on a stock car. He loves it. But no matter what brand just buy a good converter.