914 V8's: What breaks first?, Drivetrain Options

[Dunc]

All you v8 conversion guys. I hear all sorts of opinions as to what breaks when you convert to v8 power. I would like some opinions:
1. Axles: I hear that these are the weakest link. Replacing them with 911 shafts seems to be the "fix"?
2. 901 transmissions. When they fail, what breaks? The case? Gears/shafts?
3. What level of hp/torque is the limit of a 901 setup.

Thanks.

Mike

[boxstr]

Install the turbo axles, don't use first gear,I have had five v8 914s, 417 hp was the highest hp I had, perfect car. Brembo brake upgrade, and Al Davis aluminum radiator took care of cooling issues.
Craig at CAMP

[Bruce Hinds]

(IMG:style_emoticons/default/agree.gif)
CV joints are probably the weakest link. spinning one wheel in the gravel then onto pavement repeatedly will kill them just like poor driving in a V8 or high HP car will do the same when lifting the inside wheel in a tight corner.

First is a waste of time and geared too low for anything other than idling around a shopping center or starting off on a steep hill.

Drag racing or just a few burnouts can kill the ring and pinion.

HP is a product of torque and RPM - the little box was designed to handle a 300HP 6 at high RPM all day long, so torque at low RPM can be a killer. I drove the mountains of Colorado and California for 20 years like a madman with an overbored 327 and a cam that came on about 1800 and pulled like a mule through 6500. I was making about 340 HP but only a little over 300 ft/lbs.

Renegade rebuilt my 901 after about 15 years with some taller gears and said all looked well inside. It was until I side stepped the clutch one day and smoked the tires down a runway. That "did-in" the ring and pinion.

If you drive it like the road machine it was built to be, the little box will handle the v8 well.

[Mike Bellis]

All you v8 conversion guys. I hear all sorts of opinions as to what breaks when you convert to v8 power. I would like some opinions:
1. Axles: I hear that these are the weakest link. Replacing them with 911 shafts seems to be the "fix"?
2. 901 transmissions. When they fail, what breaks? The case? Gears/shafts?
3. What level of hp/torque is the limit of a 901 setup.

Thanks.

Mike

I have had several V8's. CV's break. Upgrade the axles and CV's, then you will find out what breaks next... (IMG:style_emoticons/default/biggrin.gif)

(IMG:style_emoticons/default/welcome.png)

[messix]

it's always a good idea to leave one easy to replace/fix part as a "fuse" ...

[bulitt]

There are several CV/shaft threads over in the classics section. I believe the 911 shafts are too short. The pinion in the 901 is unsupported at the front which is a weak point. Many add oiling systems, flip an H gear for 5th, stronger intermediate plate, etc... The madness begins!

(IMG:style_emoticons/default/welcome.png)

[Dunc]

Install the turbo axles, don't use first gear,I have had five v8 914s, 417 hp was the highest hp I had, perfect car. Brembo brake upgrade, and Al Davis aluminum radiator took care of cooling issues.
Craig at CAMP

Thanks Boxtr. Two questions:

1. "Turbo" axles from which years of 911?
2. Did you always use the 901 transmission?
3. The motor I have now is a 307...a bit of a dog. I am considering re-powering with an updated 302 set up.....I like the idea of an 8k RPM redline in the car. Any advice?

[Dunc]

(IMG:style_emoticons/default/agree.gif)
CV joints are probably the weakest link. spinning one wheel in the gravel then onto pavement repeatedly will kill them just like poor driving in a V8 or high HP car will do the same when lifting the inside wheel in a tight corner.

First is a waste of time and geared too low for anything other than idling around a shopping center or starting off on a steep hill.

Drag racing or just a few burnouts can kill the ring and pinion.

HP is a product of torque and RPM - the little box was designed to handle a 300HP 6 at high RPM all day long, so torque at low RPM can be a killer. I drove the mountains of Colorado and California for 20 years like a madman with an overbored 327 and a cam that came on about 1800 and pulled like a mule through 6500. I was making about 340 HP but only a little over 300 ft/lbs.

Renegade rebuilt my 901 after about 15 years with some taller gears and said all looked well inside. It was until I side stepped the clutch one day and smoked the tires down a runway. That "did-in" the ring and pinion.

If you drive it like the road machine it was built to be, the little box will handle the v8 well.

Thanks Bruce:

I appreciate the advice. I currently have a 307 in the car...its doggy. What do you think of an updated Chev 302 setup? High RPM...lots of hp, but not so torquy like a 350. I take it you would not advise changing out the 901 transmission for a 915(?)

[Andyrew]

Dunc,

Rennegade hybrids has some nice axles that use VW bus CV's and adapters. Much stronger. $700
http://www.renegadehybrids.com/

For the time being you can just keep putting used axles in. Most of the time used axles are just worn from the beginning and pop from the extra stress. If you put new or rebuilt axles in you would probably not break one for years.

901 trani will be fine for a 307 or even a 302 as long as its a mild build.

Building a 302 would be a great match and something I had planned on doing myself.

If you keep the tires small and avoid doing burnouts and anything but driving up on a trailer in first then you'll be just fine.

Biggest issues with most SBC conversions is cooling. If you dont have a cooling system in there just spend the money and buy a Rennegade hybrids setup. It works, plain and simple.

[Bruce Hinds]

Dunc,

Basically there were three common size crankshafts in the SBC series, other than the 400. I get mixed up on the 305 and 307. But torque being a product of stroke the 283 and 302 used a 3" stroke crank. The 327 and the 307(?) used a crank about 3 1/4" and the 305 and 350 used the most popular 3.48" stroke crank.

283 and 302 engines need to really rev to get the power out and then you get into the heavy duty valve train components, screw in studs, roller rockers and heavy springs. Everyday driving usually doesn't see those kind of revs(above 5500-6000) so you may not end up using the power after all.

I chose to use a bored 327(331) and controlling the low end torque with the cam, heads and exhaust. Here again, the big heads with 2.02 intake are probably great for making high RPM power, but everyday hot rodding the more popular 1.92 intakes will produce more even mind range power.

A lot of guys use the short tube headers too, they're great for making torque and creative exhaust set ups, but longer tube headers are better for the mid and upper range power and not having a crossover helps too. Without a crossover you'll have to work on pipe size to help quell the resonance.

Hope this helps.

[Mike Bellis]

The Renegade axles are really T2 VW Bus axles and 944 CV joints. The magic part is the adapters that come with the kit 100mm t0 94mm.

[Dunc]

Dunc,

Basically there were three common size crankshafts in the SBC series, other than the 400. I get mixed up on the 305 and 307. But torque being a product of stroke the 283 and 302 used a 3" stroke crank. The 327 and the 307(?) used a crank about 3 1/4" and the 305 and 350 used the most popular 3.48" stroke crank.

283 and 302 engines need to really rev to get the power out and then you get into the heavy duty valve train components, screw in studs, roller rockers and heavy springs. Everyday driving usually doesn't see those kind of revs(above 5500-6000) so you may not end up using the power after all.

I chose to use a bored 327(331) and controlling the low end torque with the cam, heads and exhaust. Here again, the big heads with 2.02 intake are probably great for making high RPM power, but everyday hot rodding the more popular 1.92 intakes will produce more even mind range power.

A lot of guys use the short tube headers too, they're great for making torque and creative exhaust set ups, but longer tube headers are better for the mid and upper range power and not having a crossover helps too. Without a crossover you'll have to work on pipe size to help quell the resonance.

Hope this helps.

Thanks for your email Bruce. I am located on the east side, but occasionally I make it over to Kitsap County. Maybe we can chat over coffee some day.

From my reading, the 302 is a 4" bore with a 3" stroke...i.e. a 327 block with a 283 crank in it. What interests me about the motor is that Chevy specifically intended it to be a road racing motor...with a fairly broad power band. Not a motor for the Saturday nite drags. I have read that a modern 302 build uses roller lifters and roller rockers---the entire valve train, as you point out, must be very light weight to function at high RPM. In any event, I want to do a build that is balanced...motor, transmission, axles, brakes.

Thanks for your help.

[messix]

Dunc,

Basically there were three common size crankshafts in the SBC series, other than the 400. I get mixed up on the 305 and 307. But torque being a product of stroke the 283 and 302 used a 3" stroke crank. The 327 and the 307(?) used a crank about 3 1/4" and the 305 and 350 used the most popular 3.48" stroke crank.

283 and 302 engines need to really rev to get the power out and then you get into the heavy duty valve train components, screw in studs, roller rockers and heavy springs. Everyday driving usually doesn't see those kind of revs(above 5500-6000) so you may not end up using the power after all.

I chose to use a bored 327(331) and controlling the low end torque with the cam, heads and exhaust. Here again, the big heads with 2.02 intake are probably great for making high RPM power, but everyday hot rodding the more popular 1.92 intakes will produce more even mind range power.

A lot of guys use the short tube headers too, they're great for making torque and creative exhaust set ups, but longer tube headers are better for the mid and upper range power and not having a crossover helps too. Without a crossover you'll have to work on pipe size to help quell the resonance.

Hope this helps.

Thanks for your email Bruce. I am located on the east side, but occasionally I make it over to Kitsap County. Maybe we can chat over coffee some day.

From my reading, the 302 is a 4" bore with a 3" stroke...i.e. a 327 block with a 283 crank in it. What interests me about the motor is that Chevy specifically intended it to be a road racing motor...with a fairly broad power band. Not a motor for the Saturday nite drags. I have read that a modern 302 build uses roller lifters and roller rockers---the entire valve train, as you point out, must be very light weight to function at high RPM. In any event, I want to do a build that is balanced...motor, transmission, axles, brakes.

Thanks for your help.

a sbc 302 is a large main journal 3" crank not a 283 crank. the 283 was a small journal crank, and the 327 block came in 2 main journal versions.

you can find a late one piece main seal 350 sbc and the crank and rods out of the l99 4.3 v8 [mini Lt1] from the mid '90s caprice. the crank is a 3" crank and the rods are longer so you can just use the 350 pistons. slap on a set of vortec heads or after market aluminum heads and you have a snappy little motor.

http://en.wikipedia.org/wiki/GM_LT_engine#..._in_bore_blocks

[computers4kids]

Dunc,
I have a mild SBC conversion, Generation 1 305, vortec heads, roller rockers etc, shorty headers, Edlebrock 7116 Performer RPM (not air gap) 1500-6500 RPM Power, with a 901 with a H gear for 5th and am very happy as a daily driver. Its a well sorted, simple conversion but it really depends what you want. Doing it again, I should have installed fuel injection and could always have used a little more power LOL. Currently, it has between 275-300 hp with 300 pounds of torque to the rear wheels-which develops mid range. Then again, no matter how much HP you have, you'll say the same thing after a while. These cars are amazing to drive with the HP.

The trend now, is not to use the traditional SBC motors but more modern motors. No matter what direction you go, to do it right it all adds up.

The 305 5.0L variant of the small-block Chevrolet introduced in 1975 had a displacement of 305 cu in (5 L) with a 3.7350-inch (94.869 mm) bore, and 3.4803-inch (88.4 mm) stroke.

[swooshdave]

http://www.edelbrock.com/automotive/mc/efi/

Not as cheap as a carb but pretty neat.

[Dunc]

Dunc,

Rennegade hybrids has some nice axles that use VW bus CV's and adapters. Much stronger. $700
http://www.renegadehybrids.com/

For the time being you can just keep putting used axles in. Most of the time used axles are just worn from the beginning and pop from the extra stress. If you put new or rebuilt axles in you would probably not break one for years.

901 trani will be fine for a 307 or even a 302 as long as its a mild build.

Building a 302 would be a great match and something I had planned on doing myself.

If you keep the tires small and avoid doing burnouts and anything but driving up on a trailer in first then you'll be just fine.

Biggest issues with most SBC conversions is cooling. If you dont have a cooling system in there just spend the money and buy a Rennegade hybrids setup. It works, plain and simple.

Andyrew,

Thanks for your advice. A couple thoughts:

1. The 302 build I envision would include a roller rocker/roller lifter valve train, hi-volume heads (2.02 exh and 1.6 in). I expect it will make about 400 hp, but maybe 350 f-p of torque. Redline at 8k. My uneducated guess is that the 901 won't tolerate it.

2. The car already has a renegade setup. With the current 307 motor, there are no cooling issues.

3. Finally....thanks for the info on axle/cv setups.

Dunc

[rhodyguy]

Is your car white with blue stripes?

[Dunc]

Is your car white with blue stripes?

Hi rhodyguy;

No it is not. I saw the blue on white one on Craigslist a while back.....it is WAAY better than mine. Mine is all white with flares and 916 front and back clips. Renegade conversion kit; Kennedy Stage II clutch; Koni adjustable coilovers in the rear; 901 transmission; drilled rotors (but 914-4 standard calipers); Amer. Racing AR61 (Centerline Style) wheels; 205 R55 15 on front and 265 R50 15 on rear. Overall height is about 1.5" less than stock. Long tube, (not tuned) headers into a single Magnaflow. Interior is stock with center console.

[Andyrew]

http://www.edelbrock.com/automotive/mc/efi/

Not as cheap as a carb but pretty neat.

Very similar to the Holley Pro-Jection that I used for years. Worked great till the ECU died, then they asked me to fork over 1400 for an ecu replacement... To which I replied f you and grabbed a new edelbrock carb for $200


The 901 can handle quite a bit in fact.. You have to baby it a little bit though. I would suggest if you want to build your motor do it, enjoy what you have in it now and take your time on the build. Then put the motor in and enjoy that while you gather some money for a strong trani. An Audi/Boxster 6 speed would probably be the best economical choice for that HP. You'll need new adapters and possibly a new clutch/flywheel setup but its a cheap and increasingly readily replacement trani. And its rebuildable (Not cheap though).

I Have around 400-425lbs of torque on my 350 and 285's on the back. With that much torque I can spin the tires at will which IMHO keeps my trani healthy. I dont drive it that much which also helps. You can run your 901 for a bit and still enjoy your car, which is really the biggest thing here.

[Dunc]

http://www.edelbrock.com/automotive/mc/efi/

Not as cheap as a carb but pretty neat.

Very similar to the Holley Pro-Jection that I used for years. Worked great till the ECU died, then they asked me to fork over 1400 for an ecu replacement... To which I replied f you and grabbed a new edelbrock carb for $200


The 901 can handle quite a bit in fact.. You have to baby it a little bit though. I would suggest if you want to build your motor do it, enjoy what you have in it now and take your time on the build. Then put the motor in and enjoy that while you gather some money for a strong trani. An Audi/Boxster 6 speed would probably be the best economical choice for that HP. You'll need new adapters and possibly a new clutch/flywheel setup but its a cheap and increasingly readily replacement trani. And its rebuildable (Not cheap though).

I Have around 400-425lbs of torque on my 350 and 285's on the back. With that much torque I can spin the tires at will which IMHO keeps my trani healthy. I dont drive it that much which also helps. You can run your 901 for a bit and still enjoy your car, which is really the biggest thing here.

Hey thanks for the input. I think your approach has a lot of merit, and I will try to learn more about the Boxter xmsn. I never even considered that.

Thanks.