Went to the track last night and only managed to trap a little over 114 in the 1/4 mile. For my mods and dyno figures, I should be considerably higher than that. My ET's were pretty bad but thats not necessarily my concern at this point. I need better grip and a little more practice at launching.

Car put down 380rwhp/370rwtq NA and 465rwhp/505rwtq on the 100 wet. My A/F was really rich at 10.1:1 when on the juice. A/F NA is in the lower 13's but tough to see on my graph. I have the correct jets in for the kit so I'm just trying to see where my mph is.

Interesting fact, when I use this calculator ( http://www.s-series.org/htm/calc/hpcalc.htm ), for my vehicle weight, the rwhp works out within 1rwhp of my dyno. I still think it should trap higher though. I assume my car weighs about 4000 lbs with me in it.

60' ET - 2.259 --- I know this needs a lot of work.
1/4 ET - 13.13
1/4 MPH - 114.3

Any ideas

 

How much do you weigh? Unless you're 300+, your weight estimate is probably on the high side. My t-top car weighs 3400 with a full tank of gas (without me in it).

Those calculators are worthless, BTW.

Now, on to the stuff that actually matters: Street tires? What size? Are you granny shifting? I improved almost 2mph just working on my shifting.

 

I weigh 250. Bulky guy with not much fat lol. I know my 1-2 shift could be quicker but I'm pretty damn fast from 2-3 and 3-4. I was running on 285/35/18's rear. I know those are not optimal at all but even if I was spinning I should have a crappy ET but high MPH correct?

-Brian

 

If you are 10.1 AF you do not have the correct fuel jetting...you may have the reccomended starting jet in the kit but you are still way to rich....you can run a smaller fuel jet to lean the car out to 11.5 - 11.8 AF...the car should pick up a little power.

Now another issue is since you are already so rich, as you are making a pass you are losing bottle pressure and going even richer

 

That was my thinking but I'm hesitant just throwing in a smaller jet without a wideband on the car. When the car was dyno'd, the A/F fell to the 10.1:1 ratio and stayed there for the entire pull. I don't doubt the pressure drop considering the bottle already had a few runs in it. You may or may not want to comment on this but should I think about putting the 75hp fuel jet it to lean it out?

-Brian

 

In general, the spinning -> better MPH idea is a myth. It can happen, but most of the time it doesn't.

I'd guess your car's weight at 3800 with a full tank of gas and you in it. If you really want to know, though, put it on the scales the next time you're at the track.

Are you granny shifting (foot off the gas and clutch all the way in, shift, clutch out and back on the gas)? If so, powershifting (keeping the accelerator to the floor, depressing the clutch pedal only enough to release the shifter) will make a HUGE difference in your MPH. I went from trapping 106.5-107.5 to 108.5-108.9 just by powershifting.

The 1-2 shift is the most important one, and also the easiest to powershift. Work on that!

What brand/model are your tires?

 

Thanks for clearing up that myth. I will work on the 1-2 shift and I am doing a midway lift on the throttle during the shifts. Powershifting wouldn't be too bad of an idea since I was shifting at 6k rpms with a rev limit of 6500. Running NA I shift at around 6300rpms but on the juice, the power peaks at 5210rpm (sounds low). I'll post my graph below.

I am running BFG KDW2's.



-Brian

 

Photobucket is blocked where I work, so I'll have to wait to see your graph.

KDW2s are a decent street tire. If you want more straight-line traction, but you don't want to go to a true drag radial, consider the Nitto 555 for your next tire.

I have a stock (6200rpm) limiter, and for the 1-2 shift, I can begin the shift when the tach indicates 5800 rpm and complete it before it hits the limiter. With my 245/50R16 Eagle F1 GS-D3s, the tires slip a lot while it pulls the RPMs down.

An aftermarket shifter (Pro 5.0 is good and not too expensive) will make powershifting much easier to do.

If you don't already have a window switch, get one before you try powershifting on the bottle.

 

I have a hurst short throw already in there as well as a window switch set to engage the juice at 3k and kill it as 6k. Came in handy when I spun so quick in first that I hit the limiter at 6500. Luckily I wasn't spraying.

-Brian

 

I have a Hurst short-throw as well (the one that came from the factory), with a custom stick (1" shorter). I've also eliminated the rubber isolators from the stock shifter setup.

It's worlds better than the standard shifter, and it holds up decently well to the occasional powershift, but after the last day I spent at the strip working on my powershifting, I'm planning on upgrading to a Pro 5.0. I don't know how to describe the issues, but let's just say that I missed a lot of shifts that day.

 

Do not put the 75 hp fuel jet in it. Read the number that is on the jet you are using and go one maybe 2 jets smaller until you find the one you need. The kits are sold with jets that work out to be a safe starting point. Sometimes they work out the be right on other times not.

As far as your trap speed goes the whole et will effect it. Leave the line hard faster et better mph. But at times some cars leave the line poorly and trap good because they make good power. But at your hp level you should be trapping aroung 121-124 mph.

Which is what I do on a 150 shot.

 

Thanks for the advice. I will take a look at the jets I have but when you refer to going one maybe 2 jets smaller, are you refering to the actual number written on the jet?

For instance (just throwing numbers out there), if I had a 0.42 jet then I should try going to a 0.41 or a 0.40 jet? Those numbers are meaningless but I am just making sure which numbers you are refering to.

Thanks.

-Brian

 

Yes that is what I'm talking about. A 42 jet is a orfice size of .042 inches.

 

What did you run off the bottle?

 

So far I've run only 109 in the 1/4 off the bottle. Same crappy launches with very little practice at the track. I know I was babying the shifts and could have done them quicker to get a little more mph out of it. I always forget to weigh the car because I think it's a pig lol. I would guess it will trap a few mph higher with quicker shifts and launching in the power band.

-brian