R154 with 28 inch tire

[JDM 1JZ]

I have been digging around the Internet and the forums and haven't been coming up with any real world experience or answers.

Does anyone have any real world experience running a 28 inch rear tire with an r154. What gear ratios are you running in the rear. Cruising RPM, gains, losses, pros, and cons.

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[black89t]

are you talking a 28" tall slick or street tire? i'm guessing a 28" tall slick unless you're off roading your mk3 lol. unless you're running 1000whp id say it's over kill and will just slow you down. i have hoosier qtp's 26x11.5x15 and they hook like a mofo. have hit a 1.5 sixty foot and that was only with one track day on them. they're great tires, very stable on the big end, and didn't seem to kill the mph. running 3.90's but going to 3.73's to get out of the hole more in first and have a higher top speed in 4th. with that combo i don't think you'll run out of gear in 4th unless into the 800+whp range because a 26" tall slick at 100+mph is taller than 26"

i had the classic mt drag radial and they're horrible in comparison. sixty foot was never consistent, they would wheel hop unless you slip the clutch perfect, and if you spin them they don't recover. the qtp's you just dump it and hold on lol. they haven't wheel hopped once and even a bad launch on them hits a 1.8. if you want to drag race your manual mk3 skip the radials and just get these. it'll be easier on the car and you'll go faster.

 

[JDM 1JZ]

Haha yeah I was talking about tires. Maybe someday I'll build an offroad mk3. Yeah right now I'm on classic m/t drag radials and they do suck. I was on a 26x11.5 tire on rx7 FD wheels before and still was loosing traction pretty good so I upgraded to 28's on weld RTS which I got a great deal on from a friend. My gear ratio in the back is 3.73 I'm more or less wondering what a 3.9 or 4.30 would do in comparison to now. I need more power getting out of the hole but I believe that is a matter of tuning my launch control and tweaking with my boost by speed settings. The car overall in its current state seems to react fine too the tire upgrade over all though.

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[JDM 1JZ]

I do plan on switching over to Pro's. They seem to work absolutely awesome.

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[black89t]

i wouldn't even bother messing with gears. if the welds are 15's just get the 26x11.5x15 qtp's and call it a day. could sell your radials to recoup a little too. to give you an idea on a prepped track 18psi is all they needed to hit a 1.5 sixty foot. they have enough hook if you lowered them too say 14psi they have enough traction to break something or lift the tires lol. prolly more so break something

especially if you're bpu the 28's are killing your mph for sure.

 

[JDM 1JZ]

I'm well above BPU I'm not sure what my signature says in here if anything, I don't really use the forums that muvh. Issue is also the vehicle isn't really used much in the track. So traction on the street from a prepped dig vs the track is night and day.

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[black89t]

yeah you can't really run the qtp's on the street that much. i drove to the drag strip on mine but its not more than 10 miles. the mt are much better for driving around and roll racing. the qtp's are for dig racing and toodling to the track. i did some pulls on the hw was fine but you wouldn't want to try to take any corners fast at all.

what are your plans for the car?

r888's hook great and can handle well to they seem to be close to the mt as far as roll racing traction.

 

[JDM 1JZ]

This is the car. It's used primarily for grudge racing. It's on a new set up so just really wondering if more gear will hurt me or not. 2JZ swapped on a borg warner.

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[black89t]

thats a nice looking 89!!!

are you grudge racing from a dig or roll lol?? thats the question. as far as gears going from a 3.73 to a 3.90 you're not going to see that drastic of a change in acceleration in boost. my car came with a 3.73 and i put a 3.90 in it for autox. off boost bogging 2nd you notice it some but once in boost its negligible. now i'm switching back because i want that extra mph out of each gear for drag racing. the 4.30 will make each gear not have enough mph in my opinion and won't spool the turbo as good. if you have the diff's sitting around you could try since its easy to swap but i wouldn't go buying one to swap.

 

[JDM 1JZ]

From a dig. Very little roll racing. I agree though the 3.7 to 3.9 wouldn't be drastic enough but maybe with a 28 tall tire maybe. 4.3 would be way too over kill probably. I'm surprised no one else has chimed in with any experience with racing on small tires.

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[black89t]

unless you want to shift into 5th under 130mph don't run the 4.30's. if you're revving over 7000rpm you'll get more mph but still most people like to make their pass ending in 4th. one more shift means more time wasted.

how much hp are you running and what you're revving to is a factor in tire choice. even though i still think you should ditch the radials. there's a reason when people are going for their fastest pass/kill they always use bias ply tires. radials work on auto's buet even then an auto launching off the trans brake really hard will be faster with the bias plys.

and this forum has really slowed down the past 2-3 years i'm sure you've noticed. oh well though i try to post here and there still though :biglaugh: