Ok to start off...

Heres my engine...

383 vortec block
195 AFR heads
288xr cam (.520/.540 adv lift.... ~.555/.576 with 1.6 rockers)
236/242 @.050
scat rods and crank
SRP 14? cc dish...(pretty sure on this..know my final scr to be 9.4:1)
Holley commander 950 MPFI 1000cfm throttle body
30 lb injectors
Tremec TKO
9" 3.5 gears

ok guys, I need some serious help here. I am not sure what my problem is, but i know that i am a full second slower than i believed I would be at the track. My best time is a 13.19.

I know that my dcr is low on this motor, but dont understand how i could be cutting such good 60' times and fall down so much on the top end

my fastest 60' (on what i found out to be a busted posi) is 1.74,and my slowest was 1.86

I was also running on 28 in slicks from when i used to have a 4.56 gear. I know that this should have hurt my 60', but i should have seen a higher mph in the quarter if i understand things right. It is hard to believe that i am falling off that much.

I would like to believe that my gearing in combination with the tire height and gear splits is my problem, but dont believe that makes up a full second in the quarter. I did notice that at WOT for those of you with the holley system that my fuel levels are dipping down to .65 on the o2 sensor.

I think that i have a host of problems, and am not sure where to start. I dont want to believe that this motor cannot work with 9.4:1 static as holley only requires 9:1 to make this work.

So my questions...

1) How much would the fuel issue affect the time?
2) Gearing and Tire Height?
3) Compression issues?
4) How am I making such a good 60' with a one legged rearend?

My 60' suggests that if my motor kept pulling...that i could be low 12's easily. especially with only launching at 2500 on a busted rear.

Any thoughts would be greatly appreciated. I worked a long time to get this motor, and am going to be sad if i cant do something to make it run like i know it can.

Thanks in advance.

Chuck Fry

P.S. I can include the log of my last pass for the 950 system if someone would like to see it.

Whats the MPH in the 1/4????? That combo should be good for mid 12's easy with the 60 foots times you are getting. I would think it should trap between 108-112 or so. What is your rpm's crossing the lights???

I am only getting to 99-101 with the mph constant across all runs. This is what is dissapointing. I am fallng down on the 2-3 shift it seems like..I am roughly at 80 mph at mid track, and gaining 20 mph over the last eighth. I dont have the time slips with me right now, but remember where I was at within a tenth at most places (cause i stared at them for about 10 minutes crying)

going to a taller tire slowed me down around 3 tenths last summer

I would suggest a few things to help:

A good convertor - 3500stall
A shift kit to stiffen the shifts
A better rear gear (w/posi) - 3.70-3.90
You don't say what suspension aids that you have but some good trac bars and shocks goes a long ways to improving ET.

Lastly, check all the engine parameters to ensure that you are in the ballpark with total timing, fuel metering and spark.

With 1.70-1.80's short times you should be in the mid 12 sec range at 120mph or so.

Are you sure your getting full throttle?? Also like other stated..check total timing . Something sounds way off. As far as gearing goes the 3.5's with a 28" tire and a TKO is not to bad. With a 383 it should pull those tires like a joke. Also what about your fuel pressure???


Lastly..what exhaust are your running??

Cfry, With 99-101 trap your are making around 250 to 260 rwhp. My wifes 2001 Mustang GT would trap between 99-100. car weighed like 3600 or so.
Its rwhp was 255 I think. I think your are missing around 50-75 hp somewhere in that combo. Slap a Holley 750DP on there and see what happens...

Cfry, With 99-101 trap your are making around 250 to 260 rwhp. My wifes 2001 Mustang GT would trap between 99-100. car weighed like 3600 or so.
Its rwhp was 255 I think. I think your are missing around 50-75 hp somewhere in that combo. Slap a Holley 750DP on there and see what happens...

But that should equate to low 14's and he's running low 13's. I don't think he is missing any HP, there may be a tuning issue, his time slips look like someone taking their foot out of it at the end of the run...

I would not swap converters with 1.7 sec 60 time with a broken posi. Fix the posi and see what that does before you make any other changes. I'm not really up on the TKO's which do you have? I believe there are 2 gear sets available, one is a 3.27 1st and the other is a 2.87 I believe. It may just be as simple as too wide a ratio and where you are shifting 2-3 is causing you to drop out of your power curve...

Dudes! TKO = Manual trans which = No converter :)

Other advice seems pretty solid. Is your clutch holding up? How is your shifting? honestly :) I know I am not that good-my 69 427 4spd bogged pretty good coming out of the hole. It ran hard after that. 13.0s at 110. I didn't want to break anything so I kept my lauch RPM below 3k. I think with a better driver the car should have hung with my 68 Chevelle which runs 12.2s @109 consistently on a 1.78 60'.

Are you 100% your timing is correct/syched up if you are controlling timing with the EFI? Sounds like you are down on power across the board other than a decent 60'.

It sounds like my car with just the primaries of the Q-jet hooked up. 60' was okay, but the power was down across the board. Lost 1.3 seconds and 18 mph in the quarter.

But that should equate to low 14's and he's running low 13's. I don't think he is missing any HP, there may be a tuning issue, his time slips look like someone taking their foot out of it at the end of the run...

I would not swap converters with 1.7 sec 60 time with a broken posi. Fix the posi and see what that does before you make any other changes. I'm not really up on the TKO's which do you have? I believe there are 2 gear sets available, one is a 3.27 1st and the other is a 2.87 I believe. It may just be as simple as too wide a ratio and where you are shifting 2-3 is causing you to drop out of your power curve...


If he is only trapping 99-101 he is down on power. The low 13 sec is due to the good 60 foot time. My wifes stang was on street tires and was cutting 2.1 60's.

What does "a busted rear" mean? Like there are broken parts thrashing aound in there? The rear end problems may be creating a TON of friction which is robbing power.

This is not a slam, but more an observation but I don't agree that your 60' times are good for your combo. We have very similar combos except I have a step bigger cam and a few more cubes but I 60' in the low 1.50's to high 1.40's. Brian does the same with a flat tappet and iron heads. I would expect your combo to be in the 1.50's, not 70's.

Your low MPH and slow e.t.s across the board tell me you are WAY down on power from where you should be. I know nothing about EFI but maybe you have a BIG problem there? That could sap power across the board.

In any event, start with the basics, not fine tuning. It's no minor problem that you have I am afraid.

When I said a busted rear, I was implying that I was only spinning one wheel on a burnout. I do believe that I have some traction issues, and was hoping to see 1.60 or better 60' times. I am in agreement with you there, but was merely saying that the 60' I was posting was way too fast for the time that I put up. I agree that power is a problem, and am going out to do some spark and fuel adjustments in about 20 minutes on a back country road....yes with someone else holding the laptop. But like I also said, if anyone wants to see a log of my last run that has the commander 950 software, and would like to helpout, i will send my fuel map and datalog in an email.

Thanks

chuck fry

Dudes! TKO = Manual trans which = No converter :) LOL Jeff... I was trying to hint by referencing not changing the converter and asking about the trans in the same breath... ;)

As I mentioned, did you sync your timing properly?

Do you have stable WOT fuel pressure?

What base map did you start with and did you modify the WOT fuel much from it?

MPH shows the HP you're making...

99/101mph got me 13.5's

102/103mph got me 13.2's

106/108mph got me 12.6's

109/110mph got me 12.3's

When I said a busted rear, I was implying that I was only spinning one wheel on a burnout. I do believe that I have some traction issues, and was hoping to see 1.60 or better 60' times. I am in agreement with you there, but was merely saying that the 60' I was posting was way too fast for the time that I put up. I agree that power is a problem, and am going out to do some spark and fuel adjustments in about 20 minutes on a back country road....yes with someone else holding the laptop. But like I also said, if anyone wants to see a log of my last run that has the commander 950 software, and would like to helpout, i will send my fuel map and datalog in an email.

Thanks

chuck fry


I bet your posi isn't broke yet. Might have the clutches/springs changed out if you can't do it yourself. The dragstrip water box is NOT friendly to the clutch type posi rears.

LOL Jeff... I was trying to hint by referencing not changing the converter and asking about the trans in the same breath... ;)


:clonk: on me :D

That thing is WAY down on power.

Ok guys I think things have taken a turn for the worse.....given that we have 2 cars with the holley system installed, I was able to troubleshoot a problem that i just noticed.

1) my msd started acting irradically ( major spark issues)

2) the commander 950 will not advance my spark curve on my computer controlled msd distributor.

So this brings my troubleshooting to a screeching halt....as i will have to call holley in the morning on getting a new box.... sux that i only have less than 400 miles on the car....and I know its the box itself as i plugged my ecu up to my fathers car, and it acted the same way.

Thanks for the input. I will continue to work with your ideas as soon as I get the computer issue resolved. This is just a major dissapointment because i had heard nothing but good things about the holley systems reliability, and have had 3 things now go completely wrong in my car.

1) on the second day of setting the fuel curve, the o2 sensor in my fathers car gave out....
2) the temp sensor in my car reads ~30 degrees hotter than what my car is acutally running (verified with a digital thermometer and a mechanical temp guage with both registering the same temp, and the mechanical being plumbed in 5 inches from the electric guage provided by holley)
3) the ecu crapped out in my car.

Overall it is not a good day for holley in my eyes, and I hope that they will be willing to work with me on the situation to get it fixed. I am not paying to get an ECU fixed that I only have 400 miles on. And yes both cars have aftermarket wiring harnesses and were wired side by side. I am not trying to bash them here....just need to vent a little before I call them in the morning...lol

Anyways I hope that everyone has had a better night than me, and again thank you for all the advise.

Chuck Fry

Look at the bright side...I think you have just found out what was wrong with the car. I figured it had to be something major to sap that much power. Once you get that sorted out you should have yourself a mid-11's car there