The Birth of Brandi's Twins [COTW 8/8/11]

[stevieturbo]

I do find it odd a lot of the very fast guys...are pulling the big speeds in 4th gear. Not sure if that's for trans strength reasons or other ?

I know tall gears can help with traction...but some are insanely tall and as you say could drop them well off the power between shifts.
Mine is just a regular 2.66 thru 0.5 gearset and TBH it's ideal for me.

Nice on the road, 6th is great for cruising and 5th will still take me beyond 200mph ( at around 7k )
As much as I know I could make it go faster than 200 over say a mile....I simply have no desire to do it for far more reasons I can list...than reasons to try and do it lol Most relating to self preservation.

For boost loss between shifts you have multiple options. Flat shifting is one, but on an H pattern not always ideal, even with some sort of cut strategy in place.

other is a basic anti-lag setup ( terminology varies across the pond ), ie a true anti-lag as per rally cars. Where boost is maintained on closed throttle. Or more accurately foot off the gas pedal.
With DBW this is pretty easy, throttle stays open a bit to allow airflow into engine, less fuel is admitted and timing heavily retarded. This will fire directly into the turbine to keep it spinning between shifts.
Without DBW...there needs to be some sort of air bypass for the throttle so can be a little more awkward.

This should make a good difference to boost recovery, as there should be almost no loss. Only caveat although less so for a straight line car, is whilst this system is operative, there will never be any intake manifold vacuum.....which can power your brake booster if you use one.
Just something to be aware of if you choose that option, but as always it isnt hard to work around. But it might be the best solution, as even if a shift didnt go quite right and your foot was off the gas for longer than expected....you should still have decent boost when you hit the throttle again

Other option would be full sequential shifts via either sequential box or the sequential shifter both of which would have a gear pot for proper closed loop shifts. That allows totally safe shifts every time in terms of power cuts.
With an H pattern mech and no means of positive gear ID....this can never be as good or safe...although it's clearly a lot cheaper.
I have everything in place for flat clutchless shifts with the H pattern, but as I've an odd habit of going 2-1 instead of 2-3....I dont use it lol

Other risk with full power flat clutchless shifts.....is the risk of breaking traction again.

Flat shifts like that or better still sequential, definitely do improve trap speeds as there is minimal speed drop during a shift. On speed/gps logs the difference is very visible and can easily be worth 1-2mph per shift.

[SSE 4 2SS]

Originally Posted by stevieturbo

I do find it odd a lot of the very fast guys...are pulling the big speeds in 4th gear. Not sure if that's for trans strength reasons or other ?

I know tall gears can help with traction...but some are insanely tall and as you say could drop them well off the power between shifts.
Mine is just a regular 2.66 thru 0.5 gearset and TBH it's ideal for me.

Nice on the road, 6th is great for cruising and 5th will still take me beyond 200mph ( at around 7k )
As much as I know I could make it go faster than 200 over say a mile....I simply have no desire to do it for far more reasons I can list...than reasons to try and do it lol Most relating to self preservation.

For boost loss between shifts you have multiple options. Flat shifting is one, but on an H pattern not always ideal, even with some sort of cut strategy in place.

other is a basic anti-lag setup ( terminology varies across the pond ), ie a true anti-lag as per rally cars. Where boost is maintained on closed throttle. Or more accurately foot off the gas pedal.
With DBW this is pretty easy, throttle stays open a bit to allow airflow into engine, less fuel is admitted and timing heavily retarded. This will fire directly into the turbine to keep it spinning between shifts.
Without DBW...there needs to be some sort of air bypass for the throttle so can be a little more awkward.

This should make a good difference to boost recovery, as there should be almost no loss. Only caveat although less so for a straight line car, is whilst this system is operative, there will never be any intake manifold vacuum.....which can power your brake booster if you use one.
Just something to be aware of if you choose that option, but as always it isnt hard to work around. But it might be the best solution, as even if a shift didnt go quite right and your foot was off the gas for longer than expected....you should still have decent boost when you hit the throttle again

Other option would be full sequential shifts via either sequential box or the sequential shifter both of which would have a gear pot for proper closed loop shifts. That allows totally safe shifts every time in terms of power cuts.
With an H pattern mech and no means of positive gear ID....this can never be as good or safe...although it's clearly a lot cheaper.
I have everything in place for flat clutchless shifts with the H pattern, but as I've an odd habit of going 2-1 instead of 2-3....I dont use it lol

Other risk with full power flat clutchless shifts.....is the risk of breaking traction again.

Flat shifts like that or better still sequential, definitely do improve trap speeds as there is minimal speed drop during a shift. On speed/gps logs the difference is very visible and can easily be worth 1-2mph per shift.

Honestly, we are looking at a sequential set up, with specific gear ratios and a straight forward/backward shift.. No lift, no boost-be-gone situations.... Much easier shifting at the RPM's we turn... The poor synchros have little chance as it is...

We also have the ability to perform flat footed shifting within the software of the ProEFI system, we just haven't programmed it yet... If we go clutchless, we wont have to worry about that anymore, and yes breaking the tires loose on shifts will become a potential issue, but we can program the tightness of the traction control based on RPM's and mph... So, loosen it a little at the shift point and let it work momentarily at each shift then allow it to tighten up and put power down... Within the DATA logs we can track when and how much it's working and adjust it as we go...

Part of the new trans set up would be a more specific gear selection for each gear, allowing for more acceleration off the line and less variance between shifts... 1-2 is substantial, 2-3 is good, 3-4 is great and 4 -5 needs a little work... On my 225.8 pass, I shifted a bit early out of 4th, roughly 1000 rpm early due to tire spin, and the car settled into a barely pulling situation even after boost built.... It just didn't want to pull very hard, which is why I was blown away when the speed ticket revealed the truth... I missed 3rd a bit, very quickly fixed, and mis-shifted into 4th as well... so I felt the run was over and resigned myself to just collecting data for the next pass... Surprise Surprise...

[stevieturbo]

PPG do their T56 setup, but IMO the ratios are poor and it's ****ing expensive. Too ****ing expensive.

Samsonas offer a good range of ratios for their 6 speed, it's also quite compact and light and certainly over here, very affordable for such a box. As to how much power it will hold unsure, although they do say nobody has broken one yet. If I ever go sequential it will be one of theirs, and I an seriously considering it. That said...my current T56 is faceplated and for road use I hate it. I'd love a synchro box again, so the sequential would kill that notion, I'd also have to lose that tall 6th gear I love ! But overall in terms of performance it would be worth it I think. Plus it's cool lol

I've used their Subaru gearbox on a couple of cars and can only say good things about it and they seem to be holding good power with not even a hint of an issue.

Their rwd box also has interchangeable transfer gears at the rear of the box, which gives you another wide range of overall gearing adjustment without having to change the diff which is handy.

Although whether 6 gears is truly a benefit for such things, harder to say. Which is back to my belief about the cars pulling so well using big gears. If I went sequential, 200+ with my current diff etc would require 6 gears. But it can do it with a good spread and a useful 1st gear.
A lot of other gearsets dont offer that spread.

[SSE 4 2SS]

Originally Posted by stevieturbo

PPG do their T56 setup, but IMO the ratios are poor and it's ****ing expensive. Too ****ing expensive.

Samsonas offer a good range of ratios for their 6 speed, it's also quite compact and light and certainly over here, very affordable for such a box. As to how much power it will hold unsure, although they do say nobody has broken one yet. If I ever go sequential it will be one of theirs, and I an seriously considering it. That said...my current T56 is faceplated and for road use I hate it. I'd love a synchro box again, so the sequential would kill that notion, I'd also have to lose that tall 6th gear I love ! But overall in terms of performance it would be worth it I think. Plus it's cool lol

I've used their Subaru gearbox on a couple of cars and can only say good things about it and they seem to be holding good power with not even a hint of an issue.

Their rwd box also has interchangeable transfer gears at the rear of the box, which gives you another wide range of overall gearing adjustment without having to change the diff which is handy.

Although whether 6 gears is truly a benefit for such things, harder to say. Which is back to my belief about the cars pulling so well using big gears. If I went sequential, 200+ with my current diff etc would require 6 gears. But it can do it with a good spread and a useful 1st gear.
A lot of other gearsets dont offer that spread.

The standard listed ratios are not suitable for my purposes, but they will custom cut pretty much any gear ratio you desire...

They also do a 6060... Corey met with them at PRI in Indianapolis... Looked at their stuff and at the stuff from Liberty Gears... The biggest issue with the LG stuff is the case is like 13 inches wide... and we would need a different bell housing... This means we would have to completely rebuild the turbo kit as my turbos straddle the bell housing flange... Time will tell which way we go... Corey did describe the power and weight of the car and the guy from PPG said no issue whatsoever... He laughingly stated it's handled 1400 hp in reverse... ..... OK.... lol... I try not to race in reverse... but get the point...

[stevieturbo]

Samsonas already have an LS fitment for theirs

https://www.facebook.com/SamsonasMot...type=3&theater

With a good range of ratios, which are then multiplied by another good range of transfer gears at the rear of the box, up or down. As said, just like changing the diff albeit with lots of increment options

https://www.facebook.com/SamsonasMot...type=3&theater

And the casing does look compact compared to a lot of gearboxes

Although comments like it will handle 1400hp in reverse....would make me question the guys. Like who would ever even do that and why ? and the chances of ever being able to apply a full 1400hp in reverse...it's just a stupid comment to make really.

A better comment would be...if you break it, we'll upgrade and replace it for free. Or give you your money back.
If they're confident their product is strong enough for anything, that's the sort of reply you'd like to hear.

[SSE 4 2SS]

Originally Posted by stevieturbo

Samsonas already have an LS fitment for theirs

https://www.facebook.com/SamsonasMot...type=3&theater

With a good range of ratios, which are then multiplied by another good range of transfer gears at the rear of the box, up or down. As said, just like changing the diff albeit with lots of increment options

https://www.facebook.com/SamsonasMot...type=3&theater

And the casing does look compact compared to a lot of gearboxes

Although comments like it will handle 1400hp in reverse....would make me question the guys. Like who would ever even do that and why ? and the chances of ever being able to apply a full 1400hp in reverse...it's just a stupid comment to make really.

A better comment would be...if you break it, we'll upgrade and replace it for free. Or give you your money back.
If they're confident their product is strong enough for anything, that's the sort of reply you'd like to hear.

I'll have to do some more looking when I have a better connection and see what I can find on their stuff... Website doesn't have a ton of information... but that may just be my slow offshore connection...

[mlee]

[stevieturbo]

There isnt a lot of info on the website, there is a little bit on facebook.

Their site says it is rated up to 1000lbft ( 1400Nm) ), so on the face of it, probably not enough.

But then the venerable old T56 was only rated to 450lbft, and many pushed double...triple through it. So it depends how much safety factor is built in to any ratings. They do claim it has not been broken yet, but then I also dont know how many users are actually pushing big numbers through it.

But it is a nice piece, the design is good and the gears are a reasonable size. Not massive though. I'm going to the UK's Autosport show in a couple of weeks and will speak to them and get some photos. I did get some a couple of years ago.

The gears are not huge, not as big as a T56, but still not small and undoubtedly a better material. The shift mech and dogs all look nice though. It would be nice to see an oil pump and spray bar for the gears though. I cant see if it has anything like that from the photos though so will check next week.

photo uploader

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Although and I may have linked it before ? This thread popped up recently over on the C5 forum. Guy looking a strong T56 and he seems to have commissioned his own custom build !

http://www.corvetteforum.com/forums/...he-market.html

[Mr Twisty]

Straight cut gears are sexy.

Happy New Year Robert & gang!

[SSE 4 2SS]

Originally Posted by Mr Twisty

Straight cut gears are sexy.

Happy New Year Robert & gang!

Thanks Mike, and to you and yours... I made it home finally, dead tired, and can't sleep... going to be a rough few days...

[stevieturbo]

Originally Posted by SSE 4 2SS

Thanks Mike, and to you and yours... I made it home finally, dead tired, and can't sleep... going to be a rough few days...

Check out that gearbox the guy on the C5 is having built....he just updated another pic today.

I wont link the pic here as there are a few....but WOW.

http://www.corvetteforum.com/forums/...post1593792731

[SSE 4 2SS]

Originally Posted by stevieturbo

Check out that gearbox the guy on the C5 is having built....he just updated another pic today.

I wont link the pic here as there are a few....but WOW.

http://www.corvetteforum.com/forums/...post1593792731

[SSE 4 2SS]

Originally Posted by stevieturbo

Check out that gearbox the guy on the C5 is having built....he just updated another pic today.

I wont link the pic here as there are a few....but WOW.

http://www.corvetteforum.com/forums/...post1593792731

I read the whole thread...

I watched the video of the pass where the car got upset... There is most assuredly a right and wrong way to deploy a chute, and this pass it was done wrong... When you activate the chute handle, there is a delay while the drogue is feeding out, then pulling the main chute out, and all of the leads, then it has to inflate... You can figure on a one second delay at least... During this time, don't lift, or do anything other than stay hard on the loud pedal to keep the weight transferred to the rear... when the chute hits, everything shifts forward... when your head comes back up from that, then lift...

Lifting too soon, causes weight to go neutral... braking before the chute hits makes this worse with forward weight shift... and then the chute hits and it can actually lift the rear of the car off the ground... There was a Lambo that had this happen at the Texas Mile with a very slight cross wind, car went end over end numerous times as a result...

I absolutely need the chute at the Beeville Tx Mile event due to the short shutdown area... lighter car or those with better brakes handle it fine, but I've had too many serious pucker moments... 5280 feet to speed up, and less than 3,000 to slow down... I've used every inch of available track on occasion... I've had guys in Vettes, tell me it's no issue... one, these particular guys are just getting over 200, two they have specialized brakes and six piston calipers... I've stood hard on the brakes for the entire shut down and still made the turn at over 70 mph...

In the video, you'll see the crash... They go to a slow motion part, and notice the brake lights are on before the chute inflates...

[Mr Twisty]

That's a sobering vid...