Which Tremec 6 Speed Ratios?

[jpndave]

RebekahsZ, My experience with cams in an LS has been the opposite. The L92 in my JK is very driveable and a beast when on the cam. I used this Comp Cams profile:

 

HYDRAULIC ROLLER-Substantial power and torque gains across the board. Hyd. Hyd. 1600 to 6700 156-401-13 267PHR14 267 281 214 228 .559 .571 114°

 

I have polished the heads (just smoothed everything up), decked to give 1/2 point more compression (making it the same as an LS3), the Phaser limiter, modified shorty headers w/merge collectors 1 3/4" primaries and the stock LS3 intake. That goes through a mildly built up 6L80E and 242 AMG transfer case. 4.10 gears and 37" KM2 tires. It runs very well both mild mannered and a beast when you stand into it. Some of that I am sure is due to the VVT changing timing on the cam. You can feel when it advances, almost like a 2 stroke engine hitting the powerband. I'd like a similar feeling in the 240 without the VVT, maybe a little more on the top.

 

I have driven a lot of different vehicles with LS swaps because of my exposure to it where I work, from 4.3L V6, 4.8, 5.3, LS1, 6.0 of many configurations (LQ4, LQ9, LS2, L76, etc.) and the LS3/L92. I have not been impressed with the 6.0, especially the LQ4 (sorry) they just feel, I don't know, they aren't at all snappy. There is definitely more torque there but the power just feels flat, stifled. They feel like an old low compression big block. Now, throw some compression, heads and a cam at them (LS2, L76) and they wake up. Honestly, my favorite engine, the sweetheart of the line is the L33. I want more power than it produces but they feel great! Basically it's just an aluminum 5.3 with LS6 heads, a compression bump and more aggressive cam that really comes alive. Every one I have driven puts a smile on your face, even in a Wagoneer. They are lively and just crisp, right there whenever you ask something of them.

[jpndave]

OK, I made up a chart to show shift and start RPM for each gear with the listed specs. I can manipulate this as needed. What do you think?

 

Axle       3.73        Tires      26”         Shift RPM            6500

Gear      Ratio      Start RPM            Shift Speed                        

1st          2.97                                      45                          

2nd        2.10        4596                       64                          

3rd         1.46        4519                       92                          

4th         1.00        4452                       135                        

5th         0.74        4810                       182                        

6th         0.50        4392                       270        

 

Cruise 60MPH    1447

                                                                               

Axle       3.73        Tires      26”         Shift RPM            6500

Gear      Ratio      Start RPM            Shift Speed                        

1st          2.66                                       51                          

2nd        1.78        4350                       76                          

3rd         1.30        4747                       104                        

4th         1.00        5000                       135                        

5th         0.80        5200                       168                        

6th         0.63        5119                       214        

 

Cruise 60MPH    1823

 

edit: I'm not sure how to make this spreadsheet display correctly, I'll try again.

Edited December 19, 2014 by Dave O

[alainburon]

I will tell you one thing, 3.73 is too much gear for that set up, especially for a street car. If you do that 1st gear will be useless. My LS7 Z06 had a fairly balanced set up from the factory and if you are getting on it you have to be on your A game or 1^st hits the rev limiter really fast. Not to mentioned I think I only used 6^th gear a couple of times because it’s too tall. Only good for fuel mileage purposes or if your are intending 200 mph passes. Even then I made my 180mph run in that car in 5^th gear. That car had 3.42 rear end with your option 3 transmission gearing.

 

That car had 345/30/20 rear tires on it and I could light them up in second gear to the point the car would get sideways. I was putting down almost 500hp to the wheels on a 3180lbs car. Now we switch to the S30, a car that has no traction control or any features to help you keep it going straight besides driver skills, it will be a handful to say the least unless you are running slicks which is not practical for street driving or almost impossible to fit in that car if you are running 18” wheels.

 

 

I decided to go with your option one built TR6060 with a T56 tail housing so the shifter sits in the proper location for the S30. I went with a 3.36 OSGiken R200. The purpose for that was to have 1^st gear a little more usable on the street as well as 6th gear being more usable as well. My motor did 621hp on the dyno N/A and 821hp on the Nitrous. On a light car like the S30 it will require some careful driving on street tires or going off the road into a tree could be a very real scenario.

 

[jpndave]

Thanks for the input alainburon. So that would look like the lower one here:

 

Axle =   3.73        Tires =   26"           Shift RPM            6500   

   

Gear      Ratio      Start RPM                  Shift Speed                                        

1st          2.97                                                       45                                          

2nd        2.10        4596                                        64                                          

3rd         1.46        4519                                        92                                          

4th         1.00        4452                                       135                         60 MPH           80 MPH

5th         0.74        4810                                       182         Cruise           2141               2855

6th         0.50        4392                                       270         Cruise           1447               1929

                                                                                               

Axle =   3.36        Tires =   26"           Shift RPM            6500

      

Gear      Ratio      Start RPM                   Shift Speed                                        

1st          2.66                                                        56                                          

2nd        1.78        4350                                         84                                          

3rd         1.30        4747                                       115                                        

4th         1.00        5000                                       150                         60 MPH           80 MPH

5th         0.80        5200                                       187         Cruise           2315                3086

6th         0.63        5119                                       238         Cruise           1642                2431

 

Edited December 19, 2014 by Dave O

[alainburon]

You are welcome sir. I choose that set up because it gives you longer, more usable lower gears 1-4 which in reality is what you will use the most on a car like that on the street. Because lets be honest not too many of us can hit 150mph on a regular basis on the streets. But it's all about personal preference when it comes to choosing gears. I also wanted to be cruzing at a little higher RPM's because with a wild cam you may have some surging in 6th gear.

 

Look forward to seeying your build come together. I too had my S30 for many years.

[RebekahsZ]

That's the tranny (the last option that you show in your spreadsheet) that I will be buying if the one I have ever craps out on me.  I managed to find a rare 3.36 R200 and have it on my shelf, but I haven't tried it out.  I definitely get out of 1st and 2nd really fast, but I don't know if I have enough power to pull the higher 1st gear out of the hole at the strip when the track is really sticky.  Plus, I knew I wouldn't be at 115mph in the 1/8-mile, nor 150 in the 1/4-mile with only 400hp, so the 3.36 was kinda out of the question.  You definitely have much more LS know-how than I do and I am a big-time noob with them.  In 1-2-3, things are happening too violently for me to be able to sense what is happening in the timing and cam, but once I get into 4th gear and have a whole 1/8-7/8 of a mile to sit and feel the engine management working, it really is cool to feel the surge that happens around 5000rpm.   I am willing to consider that the poor low-speed driveability in my truck is due to the leaf springs, helper springs and air shocks (for the trailer) and Caltracs.  The Caltracs were added at the same time as the LQ4, so I can't intellectually separate them from each other. I just knew that without some traction adders (the gov-loc GM LSD was also tossed in favor of an Eaton helical LSD), I was just going to spin in place. Probably the smartest thing you are planning is the straight axle.  Otherwise, you will be reliability limited rather than power limited.  I have had pretty good R200 surviveability, but potential breakage is always at the forefront of my mind. 

[jpndave]

This car will stay independent in the rear. I want to keep the handling. It will be strong enough to take whatever the engine can dish out. I plan on 300m stubs and shafts. We did a run of shafts for a cobra kit car company a while back so we should have the tooling. We run 300m for parts regularly. I'll use 930 or 935 CVs, and thinking a 8.8 for the center. If anyone is interested in upgrading I can run additional parts. I'm open to suggestions on that as well.

Edited December 20, 2014 by Dave O

[RebekahsZ]

The biggest issue I see with how most 8.8 or R230 IRS conversion kits is mounting of the pinion end of the pumpkin. This is the end that lifts like a traction bar under power. I have torn the floor (separated a lap joint between two floor panels, really) and I find the associated bushing broken everytime I swap diffs. Try to integrate the pinion mounting into either your roll cage or some sort of fabricated crossmember. If you look at the drivetrain forum you will find an active thread titled something like "Ultimate IRS". The guy doing it is a great guy, an engineering student who your team should look at hiring when he graduates. Pinion mounting is the only aspect of his design that I think is borderline. The rest of his set up looks good, though his kit hasn't been tested at this point. I haven't been successful in getting a really good V8 racers forum going to share "no-BS" experiences with high traction, high shock, high horsepower cars. You kinda have to learn the different personalities in this community, and sometimes we just can't seem to play well together, each of us thinking we are the only smart guy on the planet. The really big hp guys gradually drift toward 4-links, auto trans and solid rears. Probably also depends on if you are going to try to race EVERY weekend or just a few times a year. At some point, the repairing to racing ratio gets a bit tedious. I drag race about 10-15 times more often than I autocross/HPDE. May eventually develop a (2) Z-car stable with one car for turns and another for straights. And I would consider all my stuff non-competitive time trialing. No trophies on the shelf other than a couple of 20-year-old FTOD autocross trophies from a club with no Corvettes or Miatas. Ha!-I guess the Miata wasn't even out back when I won those, and the Corvette of that era was a heavy, unsophisticated, low horsepower dog!

Edited December 20, 2014 by RebekahsZ

[jpndave]

I just read up on that thread and it sounds like he is largely headed in the right direction. It was a good read other than the drama over demanding pictures on page 2 and 3. I'll try and chime in over there.

[jpndave]

Will the 26.6" at dimension "A" work with an LS into my 240 or do I need a different length? I am concerned that the shifter on these may be too far forward.

Edited December 20, 2014 by jpndave

[jpndave]

I found the length answer on SUNNY Z's thread. Looks like it is pushing it for being long enough but doable. Some of this will depend on how far back the engine is set. I'm not sure if all the kits position it the same. I'll be fabricating mounts and will set as far back as is possible.

Edited December 23, 2014 by jpndave

[jpndave]

I'm still trying to make the best decision on the transmission ratios. I may be overthinking this a bit, but, don't want to get the wrong box and regret it. Notice on these that all of the 1st and 3rd gear overall ratios are the same. With 3.31 on the low 1st set and 3.73 on the taller 1st, 1st and 3rd are exactly the same. The RPM drops 1-4 seem to be more even and consistent on the set with the lower 1st gear. Not so sure on the two overdrives. The 2.97 first gives ~2000RPM per shift drop. The 2.66 set goes more like 2200, 1800, 1500.

 

BTW, I would prefer that 6th is a cruise gear for mileage and lower revs on the engine. Thanks everyone for the input.

Edited December 23, 2014 by jpndave

[alainburon]

I found the length answer on SUNNY Z's thread. Looks like it is pushing it for being ling enough but doable. Some of this will depend on how far back the engine is set. I'm not sure if all the kits position it the same. I'll be fabricating mounts and will set as far back as is possible.

I'm not sure the excat lengths but as you mentioned it makes a big difference which mounts you use. From what I have seen the T56 with JCI mounts work great. The shifther comes out right where it should on the S30. If you go Magnum or TR6060 the shifter is too far forward with the JCI mounts. If you move the engine back by making your own mounts you may create other problems in the process like interference with the heater hoses coming out of the firewall as well as having a difficult time getting to the bellhousing bolts in case you need to remove it later, etc.

I'm using the JCI mounts and that's why I had my TR6060 modified to use the T56 tailhousing. I saw someone use the regular TR6060 and the shifther is so far forward that they had to hack up the transmission tunnel in order to make it fit. Then it is difficult to find a proper shifter boot to cover such a large hole making the ineterior looked unfished and hacked up.

[jpndave]

I can just laser out what I need for the mounts so I'll do them here. Heater outlets won't be an issue, I'll be replacing that with a new HVAC unit. The bellhousing will need to be accessible so that will be my rear positioning limit.

 

What did it take to make the T56 tail work with your 6060? Do you retain all the strength and better shifting of the 6060?

Edited December 23, 2014 by jpndave

[alainburon]

I bought mine already modified from Tick Performance. They take a brand new 6060 and modify it. They sell them already modified to handle 900RWTQ or can modify yours. And yes, you maintain all the better shifting of the 6060 without worring about fitment issues on the S30.

[jpndave]

Is this what you have here?

http://www.tickperformance.com/t56-magnum-tr-6060-conversions/

[alainburon]

yes sir, that's it.

[RebekahsZ]

I ditto the bellhousing bolts issue-maintain access to them. If installing the motor from the front over the radiator support, the tight spot for me was between the rear of the plastic intake manifold and the hood latch bracket on the firewall when tipping back the engine to get it in. Cut that bracket off and use hood pins and you might get an inch farther back.

[Phantom]

 Dave,

Let's return to one of the statements you made in your first post: "I would like to be able to do some track days and maybe autocross events but primarily a driver."

Back in 2003 I worked with John Radevich at John's Cars, Inc. It took me a year to convince him to do an LS1 installation in my 280Z.  His main business wast putting an SBC with a turbo 350 into older Jaguars so the Z and the LS were outside his main business. 14 months later I had my car and he had his conversion components he now sells world wide.

My goal at the time was to build a car that was primarily a daily driver that I could take to the track if I felt like some fun. To attain that the car had to have OEM reliability, a comfortable interior with AC and a good sound system. 11 years later I think we achieved that goal.  A lot has changed in the LS conversions for S30's since then but the difficulty in deciding end goals has not.  It's still difficult because the cars can be great at anything you want them to do - but not everything.  I chose the daily driver route so I sacrificed weight for comfort.  I had a 280 which is heavier but more rigid than the 240 and still beefed it up with a 4-pt roll bar and front & rear strut tower braces. The JCI motor mounts are designed to keep the motor clear of the firewall to allow access to items for maintenance and put the T56 gearshift in the stock hole in the tunnel.  

My car has a totally stock 1998 Z28 LS1 - probably the weakest of them all running through the option 2 T56 from a '99 Z28 and a 3.70:1 R200 LSD. That gives me identical drivetrain gearing to the Z28 although my tires are slightly smaller in diameter. The 325 RWHP of my engine through that gearing and 225/50-16 Dunlops will light up 1st but holds solidly from 2nd gear on. 

In my case 1st gear is not a waste.  I can't use all of it and I need to really be on my game but it is still a great launch gear. I'm in 6th gear all the time.  I will cruise locally at 45 MPH in 6th with the engine turning just a bit north of 1100 RPM. My 3,000 lb car is fine there. Then again, I may be running it in 3rd and getting ready for a downshift to 2nd to intimidate the guy next to me.

I never really saw what your HP goal is but, if you are really designing a car that is primarily a daily driver you're not going to put a big cam in it - just cause problems at low RPM. A smooth power band from roughly 1500 to 5500 RPM is wonderful for the street and pretty good for the track too.

The tough thing to do will to stick to the vision you have for the car, not get lost in the minutia, and remember that your car is your car. It's not mine, its not anyone else, so to your own self be true.

[jpndave]

Thanks for all the advice. Phantom, that's a good perspective to keep. It's easy to get caught up in trying to get everything and lose focus on what the primary goal is. This will be on the street 90% of the time. I'd like to be able to take it to Miller Motorsports track a few times a year and maybe to the dragstrip a couple of times. I just want to enjoy the car. That doesn't mean it can't be an extreme build, just need to stay focused. So Pro-Touring type build with some limited track time. Engine will be a slightly built LS3 (I'm also considering an LS7 or the new LT1) planning on 500 RWHP or a little more. That should be fairly easy to obtain with any of those combinations. I like the 6.2L in my Jeep and want just a little more on the top end with this car, otherwise I would be happy with that. I'll probably lighten up the rotating assembly wherever I can to let it wind up faster and rev higher. I am in the process of putting a 4.0" crank in the Jeep. I don't think that I will go that route on the Z to let it wind up faster. I'll be focusing on the lightweight parts wherever is reasonable without using unobtainium, probably bump the compression slightly, clean-up and polish the heads, free flowing exhaust, high lift on the cam would be good and a little cam timing change but don't want to go too far to have things lumpy, needs to stay really streetable.

 

On the gearing, just want to make sure that everything will work out well with the combination I am planning. Good spacing for the gears, not too low on the bottom to be roasting tires everywhere but low enough I'm not riding the clutch all the time at slow speeds. In 6th, great fuel economy and low rpms for cruising comfort but not so low that it's causing problems with the cam.