Shoaf85

Put me on the C6 list. I've never seen this list before.
2007 C6 T56 trans. Stock Longblock with UPP turbo kit and RPS carbon street twin disc clutch on 17" Hoosier slicks 28/10.5/17


Time slip below, I realized that I redlit and that messed with my head causing mw to miss shift 3rd which is why the mph is so low.....

Chris Arnold

LSOHOLIC, I'd really like your opinion regarding my situation. You seem to have a huge interest in manual transmissions and gearing correctly for launching a car. I have a 331 SBF (did I just lose you?), and a 76mm turbo. I'm trying to gear the car to go through the traps in the mid-high 150s at less than 7000 RPM. The car is currently being mini-tubbed by Team-Z and I plan to run their outlaw 9" rear with 3.60 gears, a 28" tire, and a G-force geared T56.

My options with the T56 are to run a 2.71 (9.7 total gearing) 1st gear or a 2.98 (10.7 total). With a small displacement 331, I'm concerned about coming out of the hole well. I'm not sure if I'll end up bogging or losing traction with either choice. I would greatly appreciate your opinion. Thanks,

Chris

LSOHOLIC

Will do....going to spend some time updating tonight...


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LSOHOLIC

Lots of variables....but first questions would be,
What clutch ?
What tire ?
What chassis ?
What weight ?



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Chris Arnold

It's at Team Z getting a rear end. Pretty much everything you asked is technically up in the air, but here's the plan:

- Promotion is building the T56 with G-force gears
- Promotion's preference is the Mcleod twin disk (RXT?) and a light flywheel, and I've heard great things about their clutches.
- Tire will be a 28". I'm planning to order an M&H 325/45/17 for the street, and a separate 15" wheel with a 28" slick for the track (haven't chosen the brand, yet).
- The rear end will probably affect weight, but should be in the 3400 lbs range
- fox-body hatchback with tubular suspension front and adjustable coil-overs all around.

Chris Arnold

It just changed to 3.70 rear gears, due to the fact that the only 3.60 gears available are pro gears (race only) from Richmond.

Did I lose you at sbf?

LSOHOLIC

Lol.....no, didn't lose me. I'm familiar with a small block ford..lol

Your combo probably won't be very sensitive to small differences and changes. Mainly because of the amount of power it will be making. You'd really have to have that thing dialed to see small changes.

But gear it for the stripe and do your due diligence with rpm drops and best average power in that zone. Also, depending on your power level, you may push that RXT to its limit.

SLR is your friend, but not at the expense of poor shift recovery. You should be able to put it on the chip on the line and see at least 5psi.

But yeah, bias 28's, light clutch, geared for the stripe.....are you planning of ditching the soft parts in the trans ??

You should look at Ray Bulach build as well as Poco Jangs notchback. Both are t56, turbo builds. But very different as well.

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Chris Arnold

Is this is reference to the 3.70s vs. the 3.60s? I'm really not that worried about a 3% difference in the overall ratio. I was more concerned with a 10% difference in the SLR due to the difference between the 2.71 and 2.98 1st gear.

It's too bad that only Richmond Pro Gears (drag race only) come in 3.60 for the 9". I have to decided between a 3.50 and a 3.70. Do you have another clutch recommendation? The RXT isn't on order yet. It'll come with the transmission being built by promotion.

shift recovery? Not sure what you mean by that.

Promotion built with the bigger 9310 alloy G-force gears. I think it's the best chance I have of a T56 holding up.

I looked up poco jang, and am doing my best to figure out what SLR he ran. I found his account on corral, but haven't gotten any response, so far. I've seen Ray's stuff too, but didn't know his name. I assumed he was running the stock f-body 2.66 gear. Thanks!

LSOHOLIC

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Chris Arnold

I'm leaving the synchros for now. If I go through them enough, I'll look at faceplating in the future.

Out at the track this week, I found myself questioning the 3.70s. I've set the limiter at 7200 RPM, and can get through the traps as high as 160. Poco has the current 6-speed record at 158... I think that's probably fast enough. Still, I saw a car go 160mph with an S484, they claimed. It made me think about going with the 3.50s.

I guess I'll be walking a fine line between blowing off the tire and lugging, no matter which direction I choose to go. Running the 3.70s and/or 2.98 will make it easier to prevent lugging and will allow me to launch from a lower RPM. Running the 2.71s and/or 3.50s will require a higher launch, but will allow more time in gear. It's not an equation I can solve. It's simply a matter of what works for guys. So, I really wish I could get poco to chime in with what SLR worked for him.

I understand the theory about loading the turbo and having a more usable first gear, but there must be a sweet spot, or people would just launch their cars in 2nd! LOL... So, where is the sweet spot?

LSOHOLIC

Imo......you set the car up correctly for the desired ET and power adder.

You do not handicap the car because of the power, you draw back the power to match the car that is set up correctly. Then slowly feed it more power and make the fine adjustments needed to control the new power.

This is 2015, technology is on your side. With all the available boost controllers, slew rates, traction controllers...etc...etc, dialing the power in where you want it on the track will be the key.

And that chassis can handle anything you throw at it. The chassis goes sub 1.0x all day. "Blowing the tires off" will be on your power management, not the car.

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Chris Arnold

Thank you. That is a really interesting perspective. Yes, I already have slew-rate control, and plan to send back the BS3 to gain that tuning ability with it, as well.

To answer your question about power, I'm not running in a class, and I'm not limited by my internals. As far as I know, this block and the billet parts, top of the line rod bolts, will take whatever I can throw at it. It's as you said, how much can I really put down to the ground? What will be fun on the street? That's why I've made up my mind to go with a T56, which will be more fun than a 3-speed auto to me. I think a turbo that gets to full spool around 3500 RPM will be perfect in my street car. So, I don't want to go too big. However, my current turbo is making some painful back pressure. I'm likely to swap it in favor of something between it (76mm) and an 88.

1000 was the original goal, and I expect to make near or slightly more than that with this turbo. Who knows what the future will hold, but I believe I'm unlikely to push this car higher than 1200 ever. The T56 is at the limit, the fuel system is rated up to 1400 (Weldon 2025).

I liked your post very much. My best guess is that I will run into the 150s eventually. Without another turbo, I'm unlikely to see 160s. So, I will start with the 3.70s. I will also start with the 2.71s for an overall SLR of ~10:1. I will go with the more usable first gear. The 3.70s should work very nicely on strip and street, and swapping gears if/when I make more power and need them will not be the end of the world. In fact, with the new 9", I should be able to purchase a center section with a spool that will be better for on track performance than the S-trac that I currently intend to use.

Thanks very much for your help,

Chris

Chris Arnold

So, after relentlessly scouring the forums, I found a post where Ray talked about his 60' times. This advice is to a guy with an N/A 600rwhp engine that makes 850-900 rwhp on the spray and is on a 26" tire.

Now, I'm not 100% certain, but I think that he's referring to his current turbo build, which appears to be a 364c.i. motor with a single 76mm turbo and a shot of nitrous. He could also be referring to his previous 400+ c.i. sprayed combo. He's running a 28" tire, and is making the 2.66 recommendation to a guy whose plans are to run a 26". Ray's running a 2.66 first gear, which is comparable to the G-force 2.71. He's gone 1.29 60's, but he added that "on motor" he couldn't get it to 60' for ****. He also said he hadn't launched on motor very many times. He said that spraying off of the line allowed him to bring his launch RPM down to 4500-5000 and allowed him to 60'.

Now, Ray's combo makes more power and weighs less, and doesn't 60' well without spray. To me, that means the 2.98 gear is the right answer for me. Unfortunately, when told Promotion this, I found out that the 2.98 is only availabe for the "new style" T56 with triple cone synchs, not for the old style T56 setup that I have. To upgrade everything in the transmission in order to get the 2.98 first would cost an additional $1,800 in parts. I guess all of this research and critical thinking was an exercise in futility. I don't think it matters enough for me to spend more money on a gear than a normal T56 costs in the first place. 2.71 FTW

Chris Arnold

New update: I said, "**** it," and now I'm going with the 2.98 setup with the "new style" triple cone synchronizers. It's going to cost more, but I want it done the way I want it done. I think it's really going to help me get off the line.

LSOHOLIC

Thats not the route I would have chosen, but let us know how it works out........


Although, I feel its splitting hairs between the gear sets......but at some point, the dudes who split the hairs are in the ones in the winners circle.



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Chris Arnold

No problem. Win, lose, or draw, I will follow-up eventually to let everyone know what I thought of the 2.98 first gear set.

Ironically, though you would have gone the other way, you had the biggest influence on my decision. When you said: I read into this statement a bit. With the 2.66 gear, 3.70s and 28" tires, Ray Bulach, who had more power and torque than I, had trouble with bogging on motor. To another guy, he suggested spraying in order to lower the launch RPM. I'm not spraying, and I don't want to install nitrous to avoid bog if I can do that with a gear. Once I spool up, I fully expect to have a hard time getting traction through first gear, but like you said, I can then regulate the power to maintain the limit of the car's traction, and feed the power back in as my traction improves or as I move up in gears. That's my theory. We'll see how it actually works out.

LSOHOLIC

First of all, unless this is a class car or your trying to set some records I doubt it will make a HUGE difference.And sorry for the misunderstanding.

Its all a compromise......

This is my statement that pointed towards me wanting the 2.66 first gear.

"About your SLR, IMO conventional wisdom needs to be questioned. There are smarter guys than me who have tested several different trans combos and how they impact the incrementals on the track, with-in a turbo setup.
By running less SLR it will force the turbo to work harder earlier, thus having the greatest impact on your ET. Provided your chassis can handle the early power. Also, lowering your SLR will provide less rpm drop per gear and better shift recovery per gear.
But the ultimate caveat is, with less SLR the tougher the tire control on launch.

Its all give and take, the ultimate compromise."


And about the bogging statement.......

And I would consider the differences between the launch techniques as part of the problem or solution when it comes to the bog issue. I like to use the pinnacle as an example...Prostock. They run a adjustable clutches....heres the important part.....they mechanically slip. You "side step" the clutch pedal and the mechanical design does the rest for you (pre-determined slip set up mechanically using base, counter and/or throwout bearing timers to control the speed at which the clutch "locks up"). This side step technique does not work so well with a conventional hydraulic clutch IMO.

If you watch a lot of manual guys launch technique "most" of the non IRS crowd just side steps a hydraulic clutch. Which causes very violent clutch engagement (with inadequate pressure plate rates you can have a disc bounce repeatably against the flywheel until its controlled). I find it very difficult to manage tire speed with a side step technique and a hydro clutch.

The "vette" crowd has learn that a "side step" launch can and will result in broken parts. But IMO its a lesson not picked up as quick with the soild axle cars because their drivelines are inherently stronger and can typically take more abuse.

Where I'm going with this is.........tire control and rpm control. If you listen to a guy slip a hydraulic clutch correctly you can here the engine rev and maintain an ideal rpm for the first 10-15' or so (depending on how fast the cars is, coefficient of friction, rpm, tire...etc), then begins to rev and pull through the clutch as he simultaneously releases more clutch. He has maintained tire and rpm control...just like the "Pros" do, only he does it with his left foot.

Depending on track conditions, tire pressure and the chassis, what I have found is 1/2 to 2 rotations out of the hole seems to be ideal. It allows the car to "get up on the tire" and is way less likely to bog......for the record, its way harder than it sounds (when doing it with your left foot).

Then on top of all this is the clutch choice, not all are created equal. Some dont slip worth a chit once they get some heat in them. Which of course can course some serious bogging.

I try and visualize what a converter is doing. Its slipping, allowing the motor to be in its "sweet spot" for the most allowable time. So, in short....if its bogging, its to quick of release, not enough rpm (power), or not enough tire speed and then tire pressure comes into play for fine tuning.

For the record this is just my $.02 that happens to be worth about half a penny...LOL
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Chris Arnold

Not at all; your opinion is worth more than that to me. In fact, I did not misunderstand your recommendation, either. I just read more deeply into your thought process (power management), added it to the comments from Ray (to someone else), and added my own thoughts on the subject, which resulted in my decision. It also happens that I have a "700 hp" T56 from Promotion with a stock style 2.66 1st gear on my garage floor. So, if I find issues with the 2.98 gear set, it'd only take me a few hours to swap it over, and see what kind of difference it makes.

Philisophically, I'm not a side-stepper. I prefer to control the release of the clutch. I'm a slipper, and have used that technique in everything from a stock fox-body to my current car with up to 16psi and ~800rwhp (and no traction).

I've always used the left foot to slip, but I've recently heard of a "clutch tamer," which is a product that connects the pedal to what is essentially an adjustable shock that allows both the adjustment of the engagement point and also adjustment of the rate of clutch pedal release from engagement. I think this might be the best of both worlds in that it would allow for complete release of the clutch on the street, but consistency of slip at the track. I'm planning on giving it a try if I find it difficult to slip it and launch consistently by myself.

While you may have realized and hence specifically referred to the hydraulic setups, I'm not positive that you're thinking about the fact that my setup (fox mustang) is a mechanical clutch. However, it will not be an adjustable "slipper" style clutch. Rather, it will use a Mcleod "original" street twin, which is supposedly good for 1200hp. I've never used one personally, and have no idea how well it will slip.

Before reading this thread, I'd always thought that no tire slip was preferred. Then again, it seems that advice still applies to Drag Radials, which I've always run on in the past. Now that I'll be using slicks, it's good to know that a couple rotations from the line works best for them.

I don't really have any specific goal with the car. I just want to enjoy it at the track and on the street. It occurs to me that maybe one day I will chase after Ray's record, but I highly doubt that I can currently compete at my car's weight and turbo selection. I would need quite a bit more power:weight. That said, if I end up with a more aggressive combo, I think it reinforces the 2.98 gear because I'd probably end up with a 3.50 rear gear, and a turbo that spools at higher RPM.

Thank you again for your insight and valuable advice.

Chris

LSOHOLIC

My bog ramble........was an attempt to disassociate the bog from the first gear choice. Not sure if you were picking up what I was laying down but.......just wanted to be clear. The "bog" you were talking about could or could not be related to first gear choice. And maybe more related to launch technique, regardless of gear choice.

Yeah Ive seen the "clutch tamer" that Weedburner promotes. Not sure how I feel about the operation beyond the launch.
Magnus Motorsports has a similar product out that accomplishes the same task but it is does electrically via a solenoid on the clutch hydraulics through a variable metered orifice (even though your car is of a cable design).
My only "what if" is, in theory...the device would need to be adjusted every time your at the line. As track conditions change, weather and power level. It just seems like it would eat up a lot of time fiddling with something like that. And it tends to "disconnect" the driver from the cars operation to an extent, and that is the opposite of what draws a lot of people to a stick shift car to begin with.

I plan on running the McLeod street twin with my new turbo setup as well. But I will run the Borg-n-Beck pressure plate instead of the traditional diaphragm plate.

I think your car will do fine with the 2.98

Good luck with the combo and keep us posted......



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Chris Arnold

Thanks again, man. I agree with what you said about launch techniques.