MR2 and 4age powered acrs

[AE86ITA]

Hello everyone:

Can someone share the link to the MR2(4ag) letter, the 4age powered cars and their weight adjustment in ITB???


Thanks,

[Chip42]

Not sure I follow. if you mean letters submitted to the CRB, they are not open to the public once submitted, though the decision resulting from them will be published in fastrack.

[AE86ITA]

Hello Chip:
I meant the letter that came out as a result from the mr2 owners presenting their power output. Is the letter the CRB reffered to when they decided to adjust the weight to the MR2 in ITB.

[Chip42]

Efrain, that letter is not public info, though if the author wishes to share it himself that's up to him.

I'm 99% certain that the AE86 and FX16 WILL be adjusted to 20% just like the MR2 (so 2285 and 2240). you don't need to resubmit the 4A-GE data, we're well aware it's the same motor in all 3 cases. I'm really upset we didn't get that done before the realignment started.

[Spinnetti]

Efrain, that letter is not public info, though if the author wishes to share it himself that's up to him.

I'm 99% certain that the AE86 and FX16 WILL be adjusted to 20% just like the MR2 (so 2285 and 2240). you don't need to resubmit the 4A-GE data, we're well aware it's the same motor in all 3 cases. I'm really upset we didn't get that done before the realignment started.

This is good news... Might have to dust off the Ae86... its been refreshed and "lying in wait" for the last few years....

[quadzjr]

In changing weather conditions there were two 4AGE powered cars in the top 4 (ae86 and aw11). No torque finally paid off.. though when it dried out...we went backwards in a hurry.. but it looked cool for a little bit. Haha

[AE86ITA]

Locally we only have two very short tracks(1.4 & 1.5 miles) and with a 5.37 final drive make the AE86 competitive as many of the competition either don't have it available or don't think they need it

[AE86ITA]

Just out of curiosity, if you guys weren't maxing out your speedometer have you considered changing your final drive. There are now more final drive options that could allow you to be much faster out of turns and since the free ecu rule you could drive on 5th until the brake-in(8,000rpm) point.

Thanks,

[Chip42]

Just out of curiosity, if you guys weren't maxing out your speedometer have you considered changing your final drive. There are now more final drive options that could allow you to be much faster out of turns and since the free ecu rule you could drive on 5th until the brake-in(8,000rpm) point.

Thanks,

yes, we know we could get faster in the short run with higher numerical final drive (I think that's "shorter" - these colloquialisms never make sense to me)

Steve "Quadzjr" has a 4.7 in his car and there are more of those floating around which we will snatch up when we can. but Daytona is one of our local tracks, along with sebring and Roebling, all of which are pretty high speed... at roebling we actually prefer the factory FD over the 4.7 as there are fewer shifts and less time in 5th. going MUCH shorter (right?) would make 5th tolerable and could put us back down on shifts/lap but then we're in 5th on a C50/52 box which is known for popping out of 5th as the shift mechanism doesn't have enough positive engagement of the gear, and shaft thrust will actually disengage the selector. the C52 was vastly improved and you can build to offset this problem but I've not been able to make it disappear completely.

I haven't done the math but the C52 transaxle case will be the limit on gearing, ~5:1 is probably the best we could do, maybe 5.1:1. then you throw in the weakness of the 5th on the same box and you have a dilemma. remember that flat plane final drive sets are weaker than 90° ring and pinions most of the time and you start to get REALLY small on the drive gear which means a lot of heat and the box isn't built to handle that. the box sits right on the side of the engine, has little to no cooling airflow and no provisions to make of good use of what air it does get, and adding coolers for the gearbox is not allowed. so even if there's a physical restriction of >5.1 we might not want to go there.

but yes, we are aware of the physics of it.

[AE86ITA]

I am pretty sure that either FWD or mr2 use the same FD and team M Factory has them available.

http://www.teammfactory.com/final-drive-gear_Toyota

There are also FD for our beloved AE86 and also in Weir Performance alone with some LSD repair kits

http://www.weirperformance.com/finaldrivegears.html

Hope this make our 4AGE powered car more competitive even if that means repairing the transaxle more often

[Chip42]

yes the AE92 parts should drop in to the AW11, so 5.15 is available - not far from my estimates. I still have to run the math. thanks for pointing out that M Factory makes these - I hadn't noticed and I install their products pretty regularly in our Hondas. good stuff.

EDIT - I ran some math and the 5.15 puts us pretty much in the same zone as the 4.3 OEM FD. this means places like roebling, where the 3-4 shift is all we use on the 4.3 we'd add at least 2 shifts per lap, and NOT have the conservative gear in 5th. we've already demonstrated the 4.75 to be slower at that track than the 4.3 as you ratios are more aggressive but always a bit off for the speed at key points in the track, and it adds a bunch of shifts.

sebring likes the 4.75, might well like the 5.15, especially with the hyper underdriven 2nd to pull out of traffic jams on the first few laps, and 3rd being just enough more aggressive to make the carousel, and 10 better, but 1, safety pin, tower, and 14-16 might end up being tweeners where they are clean 3rd gear sections in the 4.75.

we just don't have enough super tight corners to make use of the extra low gears - so it becomes a matter of which 3-4-5 works best for a given track.

I'd have to look at our data for the northern SEDIV tracks like CMP and barber to see what would work there.

[AE86ITA]

with 205/50-15 and a 5th gear of 0.815:1 it will hit:

- 123mph@7500rpm with a 5.15FD
- 131mph@8000rpm with a 5.15FD

-133mph@7500rpm with a 4.75FD
-142mph@8000rpm with a 4.75FD

[Chip42]

yes, I know.

[David Boles]

Wow, I wish my ITB car would go that fast

[Andy Bettencourt]

Wow, I wish my ITB car would go that fast

Those are just hypothetical numbers. Ain't no 110whp car ever going to sniff 140mph unless you drive it off a cliff.

[ajmr2]

Those are just hypothetical numbers. Ain't no 110whp car ever going to sniff 140mph unless you drive it off a cliff.

(Beverage coming out of my nose! :happy204:)

So what are the hypothetical numbers for the 4.3 gear?

[Chip42]

assuming a 22.8" wheel rolling diameter

MPH @ 8k RPM, 4.3 OEM final:
5th = 154
4th = 130
3rd = 96
2nd = 66

4.75 FD
5th = 140
4th = 118
3rd = 87
2nd = 60

5.15 FD
5th = 129
4th = 108
3rd = 80
2nd = 55

so the 5.15 is very much like a 4.3 in terms of real max speed but has tighter gears - great when you are OK ringing the motor out. the 4.75 leaves some on the table as you CANNOT use 5th that deep, but you keep more options in lower key racing and enduros to relax the mill. holding an IT prep 4AGE at 8k is not going to be something you do for long, the will may be there but... usually we shift before 7500.


wow, i wish my itb car would go that fast

me too!!!

FWIW, Steve Ulbrik's data from RRR disagrees a bit with the above, by ~1-2mph so I have to reevaluate the "assumed" wheel diameter, which is an approximation (hoho says 22.8 and 22.9 for the 205/50 and 225/45R15). relative difference is still applicable. fastest we've EVER seen Steve's 2 is 108MPH according to the RaceCapture Pro

[David Boles]

I was making a joke.

[Chip42]

yeah we know... :)

[quadzjr]

I think the joke is 108 top speed at the 2 marker at RRR.. jeez.

I was watching the video of dry race at sebring. In the dry.. I cannot touch VW's. it is like 4-5 car lengths gap every straight. Dave, you gave us a clinic on how it is done... again. haha

[Spinnetti]

Its not the top speed, its coming off the corners where it matters to me.. In my Corolla, the 4.56 just feels lazy out of the hole, where the 5.13 feels alive everywhere (I had a 5.38 3rd member too, but that was nuts). I was using up 5th gear pretty good at Mid-Ohio with the 5.13. I'm glad they made the weight adjustment... Now my former ITA car which was minimum weight when I started eons ago is back to minimum weight in ITB with my 20+ year older fatter body! Just need to get some 6" wheels if such a thing is even possible anymore and I'm back in the hunt :)

[Chip42]

what's your bolt circle - I'll point you to 6" wheels.

[Spinnetti]

what's your bolt circle - I'll point you to 6" wheels.]

Thanks.. I def. want good ones. I have Panasport UL on there now... is 4x4.5 zero offset, same as early 240Z

[Chip42]

that puts you in good shape - we had wheels made to meet the 15x6" 4x100 35mm offset market because no one else was doing it. zero offset 4 on 4.5" in 13 through 15 x6" are all over the place.

revolution and panasport of course, but also this place:
http://www.retrosportwheels.com/home.html