5 speed vs 6 speed
Discussion
playa635 said:
I was wondering when building my Ultima if a five or six speed transmission for a left hand drive GTR
What are the benefits besides price?
You don't need 6 gears as the Chevy lump gives so much torque and will pull anywhere in the rev range. I have a 6 and tend to go up or down the gears two at a time.What are the benefits besides price?
Steve
playa635 said:
I was wondering when building my Ultima if a five or six speed transmission for a left hand drive GTR
What are the benefits besides price?
What are you wanting to do with your car?What are the benefits besides price?
Lots of track work? Then a 5spd will be perfect and with the extra RPM of and LS7 you should see very close to 200 if that's your thing.
Never driven a 6spd but I struggle to justify the closeness of the 5spd ratios with shuch a wide chevy power band so I'd go 5spd.
spatz said:
LS7 can easliy rev to 7000 RPM at least that is what the manufacturer says, whereas other CHEVY motors should not
see anyhting higher than 6000-6500 depending on what make. So with 500 revs extra it sure will have a higher end speed.
Uhm, does that not just depend on what cam/valve train in general you are running. I run my SBC to 7000 on long straights, and not just once or twice, no issues (touch wood fast!).see anyhting higher than 6000-6500 depending on what make. So with 500 revs extra it sure will have a higher end speed.
LuckyP said:
738 driver said:
LS7's with extra rpm Pete??
Opps - Am I mistaken? I take my antique SBC to a (Builder authorised) 7000rpm. Doesn't the LS7 go higher?The factory's replacement 5th gear would address this, but I'm still not convinced that the std4th to custom 5th jump would be good for a 500bhp or below SBC.
On track I get 1200 jumps (about) in 3rd to 4th and 4th to 5th - which my SBC likes. Haven't done the maths but I guess the custom 5th would jump over 1500 rpm?
ls7 were reved to 8500 during initial developement but with reduced torque
so they figured 7000 is the good compromise for 150k miles or more
The stock LS7 engine have undergone industrial stress tests, whereas a builder engine is usually a new experiment with unknow reliability and performance. While investigating this ultima project i have learned that this is a big market full of believers and hearsayers ........
so they figured 7000 is the good compromise for 150k miles or more
The stock LS7 engine have undergone industrial stress tests, whereas a builder engine is usually a new experiment with unknow reliability and performance. While investigating this ultima project i have learned that this is a big market full of believers and hearsayers ........
LuckyP said:
On track I get 1200 jumps (about) in 3rd to 4th and 4th to 5th - which my SBC likes. Haven't done the maths but I guess the custom 5th would jump over 1500 rpm?
Pete,I reckon there is something fishy going on in your gearbox if you get JUMPS in revs when you change up from 3rd to 4th, and from 4th to 5th...
Regards
Edited by pilbeam_mp62 on Sunday 8th February 11:51
spatz said:
ls7 were reved to 8500 during initial developement but with reduced torque
so they figured 7000 is the good compromise for 150k miles or more
The stock LS7 engine have undergone industrial stress tests, whereas a builder engine is usually a new experiment with unknow reliability and performance. While investigating this ultima project i have learned that this is a big market full of believers and hearsayers ........
.....and dooers!!! so they figured 7000 is the good compromise for 150k miles or more
The stock LS7 engine have undergone industrial stress tests, whereas a builder engine is usually a new experiment with unknow reliability and performance. While investigating this ultima project i have learned that this is a big market full of believers and hearsayers ........
Revised on inspection of this vid to say that the std jump from 4th to 5th looks like about 1500rpm - so what is the jump from std 4th to Factory option 5th?
http://www.pistonheads.tv/clip1493
http://www.pistonheads.tv/clip1493
The stock LS7's industrial stress tests......hmm......the test of time is usually the best test.
It would seem that in the search for increased, reliable power-outputs, GM have returned to ferrous blocks and steel internals!
Alloy blocks and big torque figures never seems to be an easy combination to perfect.
Anyway, does anyone know the stock circumference of the Ultimas rear tyre so I can figure out the potential figures for my lowly four-speed/donkey paced SBC combo!
It would seem that in the search for increased, reliable power-outputs, GM have returned to ferrous blocks and steel internals!
Alloy blocks and big torque figures never seems to be an easy combination to perfect.
Anyway, does anyone know the stock circumference of the Ultimas rear tyre so I can figure out the potential figures for my lowly four-speed/donkey paced SBC combo!
Edited by 738 driver on Sunday 8th February 14:59
But in defence, none since it's rebuilt from Mr Dunn. And not for want of trying!!!I run a G96/50 six speed and the gearing matches my engine perfectly (6,500rpm changes). For a fast getaway I can start in second but I wouldn't want to do a hill start in second with my triple plate clutch, so a standard 1st gear for road use is better.
I run a higher 5th than standard due to running a custom 6th and wanting to keep the rpm drops as even as possible. Running a 0.65 in 6th I cruise at 2,000rpm at 70mph and top out at 225mph at 6,600rpm. Like everyone is saying it all depends what you want to use the car for!
Regards Dave
I run a higher 5th than standard due to running a custom 6th and wanting to keep the rpm drops as even as possible. Running a 0.65 in 6th I cruise at 2,000rpm at 70mph and top out at 225mph at 6,600rpm. Like everyone is saying it all depends what you want to use the car for!
Regards Dave
Does anyone know the exact ratios the factory uses on there GTR720, i tried to find ratios for there G50 03 box but couldnt seem to find it.
On another note i think it would be a good idea to have a Sticky thread with peoples various transmission ratios as it might help a few people, as its hard to go back and look at all the different ratios.
On another note i think it would be a good idea to have a Sticky thread with peoples various transmission ratios as it might help a few people, as its hard to go back and look at all the different ratios.
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