Auto or manual?

termcobra281

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So guys I am debating on going auto or not? I am building a higher c/r 10:5 corba with custom cams to spin 7.5 rpm. I will run a 82/85 mm precision with a 1.24 ar. I will drive it 90% on street and a few times down the 1/8th mile track. So should I do a t56 mag or go with a 4r?
 

Nightmare302

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That combo will be very very lazy with a T-56. That turbo is also very large and that 4r will need built to the teeth. The right cam profile will help spool but that combo would be miserable on the street with a stick. Talking 4500+ spool.
 

4sdvenom

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Auto with a 3800-4000 stall on the converter would be ideal. Might be able to go a little tighter but no reason too if you retain the lock up on the 4r.
That stall is perfectly stree table in the transmission too. I’ve had it in my 03 Cobra since 2004.
Except I still have a PD blower.
 

termcobra281

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Cool thanks for the input. I was thinking the auto is gonna be the way to go. Do we have any good write ups on automatic transmission swaps?
 

me32

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If your gonna be a 90% street car why not go PD blower and keep the manual?

Track car auto/turbo

Street car manual/PD blower
 

termcobra281

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Already done the change to turbo. This car is a summer time car driven on weekends and my play toy. Its almost like a motorcycle driven on nice days. Its more of a pleasure/hobby. I understand manual is better with a twin but I wanted to make a street/strip monster set up. So yea I was just wondering in that case would a manual do ok or should I just do a auto and be done.
 

biminiLX

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So you’ll only really run 1/8? 90% street pulls?
Are you committed to that single?
Auto better by far on track, especially 1/8. You could argue just for fun and not caring about track times the manual will be a fun handful 4000-7500rpm pulls.
Build what you’ll have most fun with.
For autos, the 4R MVB is like a clutchless stick in some ways but a 6R is the best current auto, just no MVB.
-J
 

me32

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Already done the change to turbo. This car is a summer time car driven on weekends and my play toy. Its almost like a motorcycle driven on nice days. Its more of a pleasure/hobby. I understand manual is better with a twin but I wanted to make a street/strip monster set up. So yea I was just wondering in that case would a manual do ok or should I just do a auto and be done.

Personally I think the turbo is too big for what you actually want the car for. Unless you had plans on street racing in Mexico.

Also i would pass on the R100 and do a 6R80 with trans controller.
 

4sdvenom

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I would stick with the 4R or a 4L80E with a MVB personally if you want a fun street car. More driver engagement with the car shifting each gear as mentioned it acts as a clutch less stick shift. Especially if you use a ratchet shifter!
The 6r will get you better track Time’s most likely but you lose the ability to shift it yourself unless you come up with a select shift type button.
I personally like ratcheting each gear up and down with no boost drop between shifts.

Ken
 

01blckcobra

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If its main purpose is street driving, be better off going to twins. With that turbo and an auto. converters not going to be happy driving around town. Going to have to run a decent sized cooler. No steam down low rpm
 
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termcobra281

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Well this is interesting... I might just have to stick with my 76/75 in that case at least I know it does good...
 

GNBRETT

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Doesnt need twins that's non-sense with todays Turbo technology. 82mm's spool up instantly these days! Instantly!

If its main purpose is street driving, be better off going to twins. With that turbo and an auto. converters not going to be happy driving around town. Going to have to run a decent sized cooler. No steam down low rpm
 

01blckcobra

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Doesnt need twins that's non-sense with todays Turbo technology. 82mm's spool up instantly these days! Instantly!
lol what technology? Turbos haven't changed it 50+years.. small 281/283 ci its going to spool ball bearing turbo at 3500 rpms. More likely it will start spooling at 4200 and maybe full spool at 45-4700. Soo take about 4-5sec to get there. you can dump a bunch of timing and yada yada, but not going to help much. Now it you have the right converter, EBC, 2-step and start from a stop, yeah probably be okay.
 

01blckcobra

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Well this is interesting... I might just have to stick with my 76/75 in that case at least I know it does good...

Nothing wrong with the 76/75 unless you're racing and trying to keep up with the competition or if you're having back pressure issues while trying to make more power. But doesn't sound like it from the information you posted above.
 

GNBRETT

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Ur right...... the Turbo's from 10 years ago are the same exact Turbo's available today. Glad we cleared that up. A current 76mm makes the same power that an 88mm made 10 years ago. Same Turbo tho and no new technology for it to do so....

281 ci is not that small. 4 cylinder cars these days are spooling up single 67mm Turbo's making 900+ hp.
lol what technology? Turbos haven't changed it 50+years.. small 281/283 ci its going to spool ball bearing turbo at 3500 rpms. More likely it will start spooling at 4200 and maybe full spool at 45-4700. Soo take about 4-5sec to get there. you can dump a bunch of timing and yada yada, but not going to help much. Now it you have the right converter, EBC, 2-step and start from a stop, yeah probably be okay.
 

termcobra281

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Ur right...... the Turbo's from 10 years ago are the same exact Turbo's available today. Glad we cleared that up. A current 76mm makes the same power that an 88mm made 10 years ago. Same Turbo tho and no new technology for it to do so....

281 ci is not that small. 4 cylinder cars these days are spooling up single 67mm Turbo's making 900+ hp.
So with everything in debate what is your take on it? With the 82/85mm precision
 

01blckcobra

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Ur right...... the Turbo's from 10 years ago are the same exact Turbo's available today. Glad we cleared that up. A current 76mm makes the same power that an 88mm made 10 years ago. Same Turbo tho and no new technology for it to do so....

281 ci is not that small. 4 cylinder cars these days are spooling up single 67mm Turbo's making 900+ hp.

Moreless the knowledge of tuning has advanced. Also talking about streetability as what the op main obj. Also talking about reving a 4 cylinder to 85-9200 rpms. Live zone its 55-6500 or so with a manual trans. Turbo tech hasn't improved much. All the same old tech that is finally being brought up because of cost back in the day. Old racer tech is what you're seeing now.

Like roller bearing in engines/ mains and cam shafts. They had that stuff in the 30-40-50s but was to expensive.
 

01blckcobra

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82/85 unless you're running a hot tune and staging it will be no fun on the street. You'll be there making a sandwich while you get gapped by a neon.
 

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