Im looking at taking the car back to the track now that the weather is cooler down here in south Texas.

Last time out was in April, with 70% Humidity. Ran a 12.02 at 112.7 1.67 60'
Race weight is 3140 w/driver...

My Tach is nonfunctional, but by using Gear x 336 x MPH / Tire, I get 5500 at the finish line with the 28" ET Streets
With that same calculator, it estimates 5900 with 26's

Honestly, from looking at F Body results with my same mods, I feel its running .3-.5 slower than it should....
Are the 28's killing me that much?
I have full front suspension and adj. uca's and lca's with shocks in the rear.
I did feel what I thought was initial traction, and then slip afterwards...
Maybe I should switch to the smaller tire and dial my suspension in?

 

I'd try to borrow a set first and try them out before making the commitment. Seems like you need to add more power to take advantage of the taller tire.

 

yeah, initial plans were to add an MS4 cam, hence the gear, stall, and tires

 

keep your 28" tires , they are a little heavier but give you better traction . what trans are you running ? as for the cam and et ...... Imo if you are running a stock cam now , swaping to the MS4 should net you about 11.20's @ 118-120 when everything is tuned in ....maybe faster good luck......

 

The weather alone could account for .2-.3 too ???

Need to find out the DA to compare. Have seen -4XX to +3XXX at same track. (over the years...not in one day)

 

Stick w 28's
As u get faster u will need the taller tire and w 4.10's u may have trouble hooking w the shorter tire.
U have money to spend, spend it on a nice 8" converter-u will lose lock up but you'll still have OD and u will be nicely into the 11's consistently.

 

Stick with the 28" tire. You will thank us later when you have more power.

 

I disagree and say you'll be quicker with the shorter tire as long as you still 60 the same.

 

I'm not saying he won't be quicker with either, but the 28" tire has a bigger contact patch and you can't argue that a wider footprint allows power to be put to the ground easier and better than a smaller tire. It also has more sidewall which allows for more bite and contributes to the wider footprint when aired down.

 

The cliffs of what you wrote are: "A 28" tire is bigger."

IF he can still hook (which he should be pretty close to, his power is not an issue for a 26" 275 series MT) he actually has a chance of picking up in the 60' because of the gearing advantage of the smaller tire. If he picks up or stays the same in 60, he will run quicker on the smaller tire.

1.67 60' isn't impressive for a 3100lb raceweight car, and I'd wager that the 28" IS hurting his 60 right now.

Going to a bigger than needed tire will slow a car down. He already put the money into the suspension, let him use it.

When he puts in the cam he'll also be upping his shift points to around 6800 if he's going MS4 so he has lots of room.

 

Are you going to put a cam in or N2O anytime soon? If so stick with the 28's. If not then go back to a 26" tire.

I bet with your mods the car will pick up ET with the 26's. I ran 26" ET Drags when my car was SI bolt-on went 11.4's @116 mph and cut 1.49-1.52 60's.

 

Well said melchoir

 

That is making an assumption that the shorter tire will hook as well. Like said contact patch is a huge part of the equation.

 

its not hard to get a 26 to hook at his power lvl, and 5500 rpms is way to low crossing the 1/4 he should be at 5900 oreven 6k to keep the car in its best powerband

 

Man, I never said the 26" wouldn't go faster and that the 28" would. All I am saying is that when he wants to put more power to the ground, it will be easier with a 28. The higher gearing it will give him if he ever puts gas on it will also be beneficial as nitrous loves to pull.

Will a 26" make his rpm's go up and keep him in the powerband he needs to be, yes of course. Will it help his E.T.'s...maybe there are added variables when going to the smaller tire, but he shouldn't have trouble hooking a 26" at his power level. Hell I hooked 26's at 720rwhp with my turbo car, but I'd of rather used 28's but they rubbed too much as the car was lowered a good bit.

28's in the long run is a better tire to run on due to contact patch, tire roll out and sidewall advantage, but yes too big of a tire can and will slow a car down that doesn't need it.

If he just bought a set of 28's he doesn't need to try and sell them to buy 26's, use them wear em' out and then re-evaluate when the time comes. If he hasn't bought either then he might be better off with the 26's, but I always thought that unless really lowered like on my old car, 26's just look plain goofy just like 25" front runners do.

 

I sold the nitrous, never got to run it since I wasnt track legal to use it.
Cam-wise, it wont be happening any time soon. maybe mid next year.

The 28's i paid $250 for them brand new through a ninja bid on ebay...
they now have about 16 passes and 50 street miles...

theres a couple of local sets of 26's that are $250 with similar use, so I wont be losing out much if I sell mine and make the switch...

or i can buy the 26's and decide which works better for me.


I do believe my car should be .3-.4 faster at its weight. I wanna believe the slower cars were pulling water into the track. there were a lot of 15-16 sec cars

 

Stay with the 28" tire - adjust gear if needed to gain the right RPM through the traps.

With the taller tire you will 60' better. I went from 26" tires and 4.10's to 28" tires and 4.56 gear. The taller sidewall was more tolerant to the initial hit. With the 26"/4.10 set up the car was on a fine line of running good or spin or bog, the 28"/4.56 setup opened that window.

Either way you go you want to make sure youre going through the traps around your peak RPM range or you're leaving ET on the table.

 

Just to clarify, are you now using 28" MT ET STREETS or 28" MT ET Street RADIALS?

 

ET streets. Soft walls, running without tubes

 

Where are you located? I have a pair of 26x10.5x15 ET Drags sitting in my garage with about 10 passes on them I would let go cheap.