Back From The Track

SCaddict

Registered User
Last time I went to the track I raced at this weekend I ran a 14.7 @94mph. I added the NPR FMIC, 75mm TB, Drag radials, Alky kit and a big raised top and this time I ran a whopping 14.8 @94mph. I thought adding performance parts made the car faster, do I have it backwards? I got 2.1 60' times last time I was there and the same this time. The guys I race with are about the same MPH and are running high 13's and low 14's in SC's with WAY less mods, but then again they are both 5 speeds. My sisters boyfriend ran a 14.3 @102 in a almost stock FWD DSM and eats me at the track but can't catch me on the street. Any ideas on why my car hates the track so much and why I keep adding parts but get slower? :confused:
 
Ok, what was the outside temp on these runs? Hotter than last time?

What about the engine temps, did you run it hot off the street or let it cool with ice bags on the intake? Also do you have a shift kit of any kind or is your trans a slushy shifting pos?

I think it has to do with the launch. You car can't get its heavy weight rolling fast. A higher stall convertor would help greatly. Also are you 100% sure you have no vacuum leaks? What about the condition of your plugs? Are you blowing out the spark? Just some thoughts.

When you ported the heads are you sure you didn't hurt them more than help them? Its hard to do if you don't know what your doing and making the ports bigger all the way through might not actually help with the velocity of the air flowing through them. From what I've seen it helps to have material welded in to the floors and then reshape the exit path.

I ran 14.6 in an SC w/ only flowmaster cat back, 5% pulley, and a K&N cone filter on the stock maf w/ rubber intake hose on cheap 225/60's.

What elevation are you at? Your car might need a tune to lean it out a tad, do you run rich?
 
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1. Get a tune. You cant just throw performance parts on a car and expect them to do their thing. Tune it so everything works together and you get the most out of your combo.

2. 94mph trap speed does not go along with high 13's - low 14's. A 94mph trap speed is consistent with mid 14's, trapping anywhere from 98-100 will give high 13- low 14 sec e.t. with a good 60ft.

3. How much air pressure are you running in your drag radials? Are you doing a good burnout with them before your run?
 
A good tune is critical!! My car started at 16+ 1/4 mile and a few little changes got me down to 13.5. Granted the mods where there but tune and tinkering are a must.
 
Scott Long said:
Ok, what was the outside temp on these runs? Hotter than last time?

What about the engine temps, did you run it hot off the street or let it cool with ice bags on the intake? Also do you have a shift kit of any kind or is your trans a slushy shifting pos?

I think it has to do with the launch. You car can't get its heavy weight rolling fast. A higher stall convertor would help greatly. Also are you 100% sure you have no vacuum leaks? What about the condition of your plugs? Are you blowing out the spark? Just some thoughts.

When you ported the heads are you sure you didn't hurt them more than help them? Its hard to do if you don't know what your doing and making the ports bigger all the way through might not actually help with the velocity of the air flowing through them. From what I've seen it helps to have material welded in to the floors and then reshape the exit path.

I ran 14.6 in an SC w/ only flowmaster cat back, 5% pulley, and a K&N cone filter on the stock maf w/ rubber intake hose on cheap 225/60's.

What elevation are you at? Your car might need a tune to lean it out a tad, do you run rich?

I should have said that the air was good and cool. I do not have a shift kit and the tranny is tight but the AOD shifts slow. Plugs are new and I am only seeing about 12.5psi so I don't I am blowing the spark out. I don't think I have any vacuum leaks either. I took the heads to a good guy that builds a lot of motors and knows what he is doing. I did bring him a list of do's and don'ts that I got from SC guys. I don't think I am running rich, but I am going to dyno the car to figure it out. The elevation was about 2500 feet.
 
super red91 said:
1. Get a tune. You cant just throw performance parts on a car and expect them to do their thing. Tune it so everything works together and you get the most out of your combo.

2. 94mph trap speed does not go along with high 13's - low 14's. A 94mph trap speed is consistent with mid 14's, trapping anywhere from 98-100 will give high 13- low 14 sec e.t. with a good 60ft.

3. How much air pressure are you running in your drag radials? Are you doing a good burnout with them before your run?
I know a guy with an almost stock XR7 (SC) at the same track that runs 13.9 @96mph and another SC, again at the same track that run 14.4's @95mph. I am running 15-16 pounds in the DR's. I do a good burnout and get them heated up good.
 
You've got 15% OD
and you've got 30 LPH injectors

Your running lean and the car is pulling timing out to prevent detonation. Don't take my word for it thoe :) Just look at your times.
 
Marty, let's get your car on the dyno and see what she does. We'll study the graphs (as many as we can get from Matthew) and go from there. Maybe we'll pull your computer out of it's stock hiding place and check to see about a chip. Call me when you see this.
 
If you have 15% OD and 30lb injectors you are running out of injector, probably by about 4500rpm. The dyno should verify this. An AOD runs out of injector at about 240rwhp. Also, what are your shift point rpms?

With the alcohol injection and no tune, I would personally pull the knock sensor but that's just me.
 
David Neibert said:
I think it's the blower.

David
David,

We switched blowers and that did not change a thing. So we went back to the original blower and changed the bypass and that never did anything either. I am seeing a little more boost with the snow kit though.
 
XR7 Dave said:
If you have 15% OD and 30lb injectors you are running out of injector, probably by about 4500rpm. The dyno should verify this. An AOD runs out of injector at about 240rwhp. Also, what are your shift point rpms?

With the alcohol injection and no tune, I would personally pull the knock sensor but that's just me.
David,

I will try and get it dyno'd as soon as I can. I shift the car at about 5400 rpms.
 
Freak

super red91 said:
2. 94mph trap speed does not go along with high 13's - low 14's. A 94mph trap speed is consistent with mid 14's, trapping anywhere from 98-100 will give high 13- low 14 sec e.t. with a good 60ft.

Guess I am running some sort of super freak, as I have indeed run a 13.987 @ 96.36. Or maybe I am a better driver than I give myself credit for.

Dave
 
Big Cat Davo said:
Guess I am running some sort of super freak, as I have indeed run a 13.987 @ 96.36. Or maybe I am a better driver than I give myself credit for.

Dave
Dave,

We all know that you have a big "S" on your chest. :) I will get this sorted out and run 13's.
 
I'd do one of a couple things if I were you.
o First off, is dropping the 5% jackshaft pulley off until you can get larger injectors (if money is an issue)
o Second option would be to just get larger injectors.
o Third (not really an option if you want to keep your SC in running condition) is the tune. I think that's been beat enough though.

Just for your info, I've got a lot of similar mods as you. I'm running around 8% OD on a gen II blower with my stock 30lb injectors. My combination yeilds roughly 255 rwhp before I run out of fuel at 5200 rpm. If you don't have the cash for injectors and a tune, I'd put the stock jack shaft back on and get the dyno tune. The snow kit will help cool, but if you don't have the fuel source to keep up with the volume of air, you're going to run lean.

Even by dropping off the 5% jackshaft, you're going to have more useable rpm which will make your SC faster. Unless you get larger injectors, then you're good to go with that tune...
 
SCaddict said:
Dave,

We all know that you have a big "S" on your chest. :) I will get this sorted out and run 13's.

Not directed at you Marty, just letting the folks know what others at the track you were running at were running and with what mods, I know my time at the top of the Alberta SC pile is a limited one.

Dave
 
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