Calling on all “gear heads”

[MikeD930]

MZ3,
There was no reason on my part to show shifting at 6000 rpm...I updated the original charts to show shifting at 6500 rpm to be inline with your earlier postings.

I agree that using taller 3rd (.828) and 4th (.514) gears with 8:41 R&P would be ideal. If you can't find .51 gear then using stock 9:36 R&P with lower 2 & 3 gears would work. Can you explain why you find stock 3rd gear to be useless? Too tall? Too much gear spacing between 2nd or 4th? Keep in mind that when lowering 2nd and 3rd gears would cause more gear spacing between all gears except 1st & 2nd. It's really tough to decide what is best for your type of driving. I used to have short 2nd (1.60), 3rd (1.12) & 4th (.792) gears which was great for twisty roads but got tired of high rpm on highway. Now with my gearing it's great on the highway but sometimes missed having short gearing. It's a trade off. I think the best compromise is to have slightly shorter 2nd, 3rd & 4th gears with stock 9:36 R&P.

I added another chart that shows both type curves superimposed (blue is your current gearing setup and the red is with stock gears and 9:36 R&P. Perhaps this will help give you an idea of how you want to gear your car. As you can see the taller the gearing the flatter and lower its thrust curve. Also, you mentioned that you may install a better turbo later. I think this will give you broader curve assuming boost occurs earlier.

[MZ3 SBC]

Originally Posted by MikeD930

Can you explain why you find stock 3rd gear to be useless? Too tall? Too much gear spacing between 2nd or 4th? [/img]

I appreciate you putting that additional information together. Why I say the 9.38 with .89 is useless is because in MY real world driving its too tall. 2nd handles 30-90mph... I am not flying around public roads 70-140 MPH ...if that makes sense. I am sure many will disagree....


....With the 8.41 /the 1.3 and .89 is really awesome and where I spend the most of my time.

Moving on....after reflecting on every ones comments, reading some additional threads on Pelican, and having a solid conversations I decided on going back to the 9.38 using a 2.533, 1.53 , 1.034 and .625 Thanks for all the input!!

[MikeD930]

Originally Posted by MZ3 SBC

... I decided on going back to the 9.38 using a 2.533, 1.5 , 1.034 and .625...

I think you should stay with stock 1st gear (2.25) instead of 2.533. Your proposed 2nd & 3rd gear is ideal. What's your reason for 2.533 1st gear? I'd be concerned about large gap between 1st and 2nd. My current gearing is 2.25, 1.444, .928, .625 and I'm satisfied with gear spacing between 1st & 2nd.

[MikeD930]

Originally Posted by MZ3 SBC

I appreciate you putting that additional information together. Why I say the 9.38 with .89 is useless is because in MY real world driving its too tall. 2nd handles 30-90mph... I am not flying around public roads 70-140 MPH ...if that makes sense. I am sure many will disagree....


....With the 8.41 /the 1.3 and .89 is really awesome and where I spend the most of my time.

Ahh...that makes sense regarding stock 3rd gear not ideal in your case. Everybody's needs are different so ignore those who disagree!

[MZ3 SBC]

Originally Posted by MikeD930

Everybody's needs are different so ignore those who disagree!

You have a good point. I just looked at keeping stock first gear.....and it seems to make the steps 1-2, 2-3 look better.

The reason I went 2.53 on first gear was simply based on the concept that the more torque at the wheel, the faster the acceleration and for a good compromise between acceleration and drivability....getting into 2nd sooner would achieve that ....it is almost like splitting hairs. I a use to selecting gear ratios for specific tracks as appose to 3 different objective;
0-60, back country rips, highway cruising. That RUF gear box!!

I think these are all in a ball park. It comes down to what gears are available and what the builder decides.

[MZ3 SBC]

As I continue to read through old threads and posts I can't help but reflect on how these cars have captured the passions of driving enthusiasts and they have engaged in the same journeys ......and thankfully there are these threads to review. This one discusses the noise related to the an 8.41 Ring and Pinion. Check it out.

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/777947-fs-930-ring-pinion-8-41-a.html

The question is.....is the noise you are hearing the "good" noise or a "bad" noise. A good noise is the sound of Hans J Stuck in the M3 GTR at the Nurburgring ( see below) with the straight cut gears s screaming .....VERY Awesome Noise...but thats on a track at WOT and not lumbering around on the highway which is real world.

https://www.youtube.com/watch?v=jkQmXueWIio

A bad noise is a sign that something is wrong even though it sounds good.....Maybe the bad noise is a worn out R&P or a bearing.

I found the 8.41 SCHEMA somewhat noisy but I was ok with it- its what I call a good noise. Unfortunately the clutch and 3rd gear syncro went....so it was do for a service.

The whining starts as the trans comes up to temp and I am driving at low RPM off throttle ...you get the zugh zugh zugh but higher pitch sound when on throttle.

My feeling was if there is nothing wrong with the transmission and its the the way 8.41 sounds.....thats a good noise...but I still need a taller 4th and there isnt any 4th gear tall enough to get that done....so I either live with it or go back to the 9.38 R&P and put in those new 1-3 gear ratios.

Will see what Dawes Motorsports finds as they progess,,,,,,

[MZ3 SBC]

I was looking into the gearing choices that PCNA put into the GT3 RS and Cayman GT4....these both have pretty tall gearing....certainly NA motors and way more gears than 930 ....so not apples to apples....but the exchange on the topic is excellent...

Check it out.....

https://rennlist.com/forums/997-gt2-gt3-forum/331297-gear-ratios-of-997-gt3-2.html

[MZ3 SBC]

Originally Posted by RarlyL8

I was thinking in terms of gearing to optimize torque, not gearing just as an overdrive to stay out of boost while cruising. That's a different deal. Do you normally run at 110mph?
.

I was thinking about your comment Brian. ...I wish I was driving at 110 all the time. The fact that I am not driving at those speeds and higher often is exactly why I would like a taller 4th....I dont really mind if going taller in 4th will cause a bigger step from 3rd to 4th since I will not be racing at those those speeds....but using 4th to comfortably drive on the highway. I want the same gearing in 4th that all the stock geared 930 have today......thats (9.38 /.625 or 8.41 /.514)....so I think we kina agree on this.

Where my view is different pertaining to not needing gearing when more boost can be had ( if thats what you said) ...is that I think shorter gears with or without a turbo....and regardless of whether you have low spooling turbo or not....is faster. Is it required? certainly not ...and much less so with a low spooling turbo.

But the bigger the wheel the torque the faster the car will accelerate....to the maximum / peak RPM a motor. the turbo just helps you accelerate faster....provided the turbo can spool efficiently to the red line as well. Thats my take. The one part of the calculus that I would love some one to comment in on...is how gearing and time in each gear effects spooling / heat for turbo....My guess it it makes no difference how quickly a car accelerates to 6500 RPM...so why not accelerate as quickly as possible....

I recognize that choosing gearing stacks for different road courses introduces a different set of variables ....and you have to select the gearing that will be most effective to improving lap times.....Nurburgring /Road Altanta vs Limerock ( differet topic)


The 8.41 helps get the car going quickly and then the boost joins in on the fun....and the motor with SC cams and ported intake helps he motor rev ....adding a lower spooling turbo like the K27 7200 Raptor will only make things better.....

and if you want to accelerate from 0 to 150 with your stock gear stack and dont care about 600 more RPM in 4th gear for a given speed on highway....then the 8
.41 or 8.37 is faster than 9.38.....RUF had it right! short 1-4 and a real overdrive 5

[WERK I]

MZ3 SBC,
I'm curious. When are you seeing the onset of boost? I have almost the same setup as you and I see onset (.2Bar) at 2800RPM. When I'm driving driving Interstate speeds (70MPH@~3100RPM), I'm always in Boost Mode.

[MZ3 SBC]

Originally Posted by WERK I

MZ3 SBC,
I'm curious. When are you seeing the onset of boost?

I see full boost around 4000. I am hoping to see an improvement now that I had the turbo serviced. I sent down to Charlie at Evergreen who refreshed and added the billet compressor wheel. HE said it was coked up and very tired.

I was told to expect FULL .9 bar boost now around 3500 RPM. Once the car is back together and new clutch kit broken in, I will schedule a fuel pressure / fuel service...make sure the plugs are all firing, the injectors are not clogged and do a few pulls on same dyno to see where things are. Next step will be a 7200 Raptor or GTX 35r.....but I want to see how this turbo mod does first.

Which turbo and headers are your running ( just saw you have the k27 hybrid and fabspeed)? From what I heard from Charlie that should spool much lower than me...but not boost as high in RPM as the 7006 or the raptor 7200 60mm

I have a few roll on videos on my IG page where you can see the boost build.

[krasuskyp]

fun thread, been *awhile* we've had one here it seems sometimes

Errrrr:

Originally Posted by RarlyL8

Do you normally run at 110mph?

Normal's overrated. lolz. I. Know. Nuthhhin.

and

Errrrrrrrrrrrrrrrr...

Originally Posted by gsxrken

Ronnie's taste for men was acquired long ago...

DEFFFFF been tooooooooooooooo long (the way ole 'Raw craves in only a way ole 'Raw can) since had onna 'these' here rofl... great call-out Kenster!

OP, I recall yer handle but not your car - how bouts a pic fer thread color yes? 8 ) Dawe builds nice stuff. (always wondered what became of Peeling's metallic '79 build from CT here). How far down in Joisey you?

Cool charts MikeD! Well done.

(always love the decorum here as well, I'll add - Brian's / Matt's advice on-point. Solid folk)

[MZ3 SBC]

Originally Posted by krasuskyp

fun thread, been *awhile* we've had one here it seems sometimes


OP, I recall yer handle but not your car - how bouts a pic fer thread color yes? 8 ) Dawe builds nice stuff. (always wondered what became of Peeling's metallic '79 build from CT here). How far down in Joisey you?

(always love the decorum here as well, I'll add - Brian's / Matt's advice on-point. Solid folk)

Here is a picture of the car.....where you referring to my car 👆Peelings 79? Tell me more ...::


I appreciate everyone’s conments , feedback and experiences ....

[speednme1]

Originally Posted by krasuskyp

fun thread, been *awhile* we've had one here it seems sometimes

Errrrr:



Normal's overrated. lolz. I. Know. Nuthhhin.

and

Errrrrrrrrrrrrrrrr...



DEFFFFF been tooooooooooooooo long (the way ole 'Raw craves in only a way ole 'Raw can) since had onna 'these' here rofl... great call-out Kenster!

OP, I recall yer handle but not your car - how bouts a pic fer thread color yes? 8 ) Dawe builds nice stuff. (always wondered what became of Peeling's metallic '79 build from CT here). How far down in Joisey you?

Cool charts MikeD! Well done.

(always love the decorum here as well, I'll add - Brian's / Matt's advice on-point. Solid folk)

I always wondered about John’s car..and John. Great dude. Hopefully when the summer hits we can all meet up.

[krasuskyp]

Originally Posted by speednme1

I always wondered about John’s car..and John. Great dude. Hopefully when the summer hits we can all meet up.

Dood, right? Never heard. He was considering a Diablo @ the time, I of course devilshoulder'd that

And, DOOD... RIGHT? T'was just sayin same to Mr. MZ3 here, mentioned he's close to you. Paging Alexxxxxxxxxxxxxxx to the White (930) Summahtime 'Paloozer Courtesy Phone?

Bueller... Bueller...

[David]

My vote is for stock R&P and 1st gear with 2 step shorter 2nd & 3rd and 1 step shorter 4th.

Here's my 930 accelerating to redline in 1st and 2nd with a stock 4-speed. Notice it takes about 1 second from onset of boost to redline in 1st gear. No need to be shorter than that.

https://youtu.be/MljAsvAECA8