how much boost?

[Need2Speed]

Well with that in mind do you think I could break 13 seconds. I felt like i botched up the launch with that run. Do you think a short shifter will help? Do you think the boost levels will change since I have the better turbo?

[JekylandHyde]

To quote myself:
"I also would not run over 15 psi without either: race gas, upgraded intercoolwer or water injection. Personally, I use all three and run 22 psi out of a bigger turbo "

Running a 12 sec pass is not going ot be easy. The ct20b and teh ct26 are roadcourse type turbos ... not designed for drag racing ventures. You can get a ct20b in to the 12s (there is one in the 11s), but it takes perfect driving and supporting mods.

With good driving you should be able to hit low 13s at 15 psi.
The biggest way you can improve your ET ... is to practice.
You will gain as much as .5 from practicing, IF you are learning nad improving your driving.

[HondaChili]

Originally Posted by JekylandHyde

Your launch sweet point will probably be around 5500 rpms, you should shift around 6600 rpms in 1st gear and around 5500rpms in the rest of the gears. (unless you have the CT20B turbo, not the CT26).

Wow 5500 rpm launch? wouldnt you peel too much on launch? And can you explain the reason why shifting at 6600 and 5500 is better than shifting at redline, im not too sure how that can maximize your speed. Well on another note, i dont drag too much anymore cuz i heard a mr2 launch is bad for the car, since we has lsd and all that weight on the back tires it might be a lil too much for car to handle, is this true? Well untill i reinforce my axles and rods , im not launching my car.

[scarecrowX]

Originally Posted by HondaChili

Wow 5500 rpm launch? wouldnt you peel too much on launch? And can you explain the reason why shifting at 6600 and 5500 is better than shifting at redline, im not too sure how that can maximize your speed..

well, i'm a road racer, not a drag racer, but when we do standing starts, you don't do them by dumping the clutch and modulating the gas, you "dump" the gas and modulate the clutch. higher revs keep it from bogging.

as for shifting, the CT26 runs out of breath at about 5500rpm. there's little to gain by staying in gear after the motor has stopped making power. you will accelerate faster if you drop the rpm back down to a range where the turbo can still make effective boost.

[HondaChili]

yes but even if you were to modulate the clutch wouldnt it still be very hard to keep the tires from peeling? i mean controlling such a launch is very hard. I say ease the cutch at 3000 and eliminate the error percentage. and besides clutches arent cheap.

[JekylandHyde]

Originally Posted by HondaChili

Wow 5500 rpm launch? wouldnt you peel too much on launch?

With the OEM turbo you may be able toget awa ya little lighter ... 4500 -5000 rpms. Yes, you would peel out if you dump the clutch. We are talking about the finesse of launching, not dumping a clutch. I would refer to it is a "quick-slip, dump". Basically I slip the clutch very quickly and got WOT/dump when I feel the "tug" of the car.

Originally Posted by HondaChili

And can you explain the reason why shifting at 6600 and 5500 is better than shifting at redline, im not too sure how that can maximize your speed.

You want to race in the power band. The stock CT26 turbocharger on the MR2 has no powerband above 5500 rpms.

Originally Posted by HondaChili

Well on another note, i dont drag too much anymore cuz i heard a mr2 launch is bad for the car, since we has lsd and all that weight on the back tires it might be a lil too much for car to handle, is this true?

you're kidding right? Everything you listed is exactly why the MR2 IS a great car to luanch. LSD = traction. Engine over the power wheels .... in Japan, the MR2s are classified with the AWD drive cars because their launches are so great.

Originally Posted by HondaChili

Well untill i reinforce my axles and rods , im not launching my car.

The only thing to be concered about is breaking the CV Joints ... and that tends to happen if you have over 300 rwhp. I broke them once. ATS Racing offers an upgraded CV Joint (which I now have). No problems here. I slip/dump my race clutch at 6000 rpms!

Originally Posted by HondaChili

yes but even if you were to modulate the clutch wouldnt it still be very hard to keep the tires from peeling? i mean controlling such a launch is very hard.

No one ever said it was going to easy

Originally Posted by HondaChili

I say ease the cutch at 3000 and eliminate the error percentage. and besides clutches arent cheap.

If you ease the clutch at 3000 rpms, yo uare going to bog, your turbo is going to lag and it will take an eternity to get off the line. You wll in act increase your "error percentage". In a dragrace I would rather have some wheel spin off the line than have my turbo lag.

Yes, clutches aren't cheap. Neither are tires, axles, etc ... if you are going to race, yo uare going to eventually break things. There is no way around it. If you are going to baby the car off the line, what is the point in racing?

You will never see the potential of your car unless you are willing to explore it.

[JekylandHyde]

Generalized formula for figuring out shift points:
Lower gear ratio / higher gear ratio X RPM at peak Torque = Shift RPM

Applied to the STOCK CT26 Turbo:
Using the same formula for a stock CT26 MR2, I get shift points:
1st --> 2nd = 6595 rpms
2nd --> 3rd = 5643 rpms
3rd --> 4th = 5595 rpms
4th --> 5th = 4915 rpms

That is true regardless of power output unless you change the peak torque point.

Notice how both of these ct26 cars with varying mods have the same peak torque point:

276 HP CT26
http://www.turboforum.net/dyno/image...ns/dyno276.jpg

161 HP CT26:
http://www.turboforum.net/dyno/image...redmr2dyno.gif

Same turbo, same shift points :thumb:

[HondaChili]

Wow , i never expected such a detailed answer. Thanks alot hyde, it was very informative. I have to admit i do feel a little safer about launching however i am still a bit skeptical, probably because im not used to the hard shifts on lsd. It feels like i snapped something everytime, but thats just me. So with that being said i end this post since hyde has absolutely given me no more room for questions. Dman you hyde!!! i will stump you one day..... one day!!!!!!!!

[scarecrowX]

Originally Posted by HondaChili

I have to admit i do feel a little safer about launching however i am still a bit skeptical, probably because im not used to the hard shifts on lsd. It feels like i snapped something everytime, but thats just me.

are you sure you're shifting properly? a good shift is heard but not felt. the only time i ever feel my shifts is when i do them slowly..

[HondaChili]

maybe im not doing it correctly, but im still learning.