RPM limit

Leon · February 08, 2007, 01:04:18 AM

Tony, or anyone else - What's the rpm limit on a C4? I'm thinking about spinning one up to 10 or 11K if possible.

rumrumm · February 08, 2007, 09:42:52 AM

Not possible. NASCAR engines, which have the best parts in them, hit about 9300 rpm and that is not sustained. It all depends how many mods you make in the engine. Heavily modified as a drag engine, you might see 8500 rpm max.

tomslik · February 08, 2007, 10:02:44 AM

i suppose that depends on what eng is in front of it...
hint,hint,hint....
tell us more

Leon · February 08, 2007, 12:44:24 PM

I am working on a Honda B18 engine that will have the deck height increased to handle a longer rod, may even destroke the crank to get a high rod to stroke ratio. The valve train has been tested to 12.5 so it is no problem. I'm sure the engine will be capable of the rpm, just wondering about the tranny.

rumrumm · February 08, 2007, 01:05:27 PM

Quote from: "Leon"I am working on a Honda B18 engine that will have the deck height increased to handle a longer rod, may even destroke the crank to get a high rod to stroke ratio. The valve train has been tested to 12.5 so it is no problem. I'm sure the engine will be capable of the rpm, just wondering about the tranny.

Are we talking motorcycles or Corvette's here?

sirstude · February 08, 2007, 01:16:35 PM

Quote from: "rumrumm"
Quote from: "Leon"I am working on a Honda B18 engine that will have the deck height increased to handle a longer rod, may even destroke the crank to get a high rod to stroke ratio. The valve train has been tested to 12.5 so it is no problem. I'm sure the engine will be capable of the rpm, just wondering about the tranny.

Are we talking motorcycles or Corvette's here?

http://en.wikipedia.org/wiki/Honda_B_engine

rumrumm · February 08, 2007, 01:23:01 PM

Sorry! To me a C4 is a Corvette.

Mikej · February 08, 2007, 02:02:26 PM

You are talking about a c-4 ford transmission?

Leon · February 08, 2007, 03:09:15 PM

Sorry about that - yep I mean tranny. I'm not sure how much rpm it can handle or if there might be some other problem at that rpm. The B18 engine is a car engine that has been hot rodded for quite a few years for street and drags. They are capable of a lot of power from a small package.

tomslik · February 08, 2007, 03:24:46 PM

hey, something else occured to me, do the b's run backwards?
i'm serious here....

the 94 accord(only honda in the shop right now)runs CCW...
but it's not a B

1FATGMC · February 08, 2007, 03:39:41 PM

Quote from: "tomslik"hey, something else occured to me, do the b's run backwards?
i'm serious here....

Only if you are in reverse

!!! I'm not serious here..........

Sum

GPster · February 08, 2007, 04:09:22 PM

I can understand the question and I don't know the answer but what kind of RPMs did the Mazda rotary engines turn? Maybe that is a different place to look. Another part of the plan might be more about the torgue converter. An engine that's capable of that type of revs might not deal well with a converter that's locked at 1,500 RPM. Just wondering, are you thinking about a C-4 because the bellhousing is separate from the trans body so that it would give you more room to adapt the engine to the trans? Here might be a totally dumb way to look at it (but it won't surprise anyone that reads my posts). Ultra-light aircraft engines sometimes use a gear (or chain) reduction when they use automobile engines because an auto engines peak RPM is a lot higher than the RPM capability of the props. Maybe you can put some kind of reduction between the engine and the trans to keep the trans closer to it's limit. I try to keep it together but I forgot where I left it. GPster

Leon · February 08, 2007, 06:07:54 PM

Quote from: "tomslik"hey, something else occured to me, do the b's run backwards?
i'm serious here....

the 94 accord(only honda in the shop right now)runs CCW...
but it's not a B

I'm aware of that, but we will be spinning it CW by rephasing the cams (since intake and exhaust are separate that is easy), ditching the stock oil pump and going dry sump, and ditching the water pump and going electric. There's a few minor things, but working with Crane Cams, we see no reason why we can't run it CW.
I'm thinking the C4 for several reasons, the separate bell housing, the power it can handle exceeds what I think I will produce, it takes less power to turn than several others, and I have a couple of them on the bench. That is probably the major factor since they are free. One has been beefed up already. I can get a high stall converter cheap so that isn't a problem. This combination is going into a F86 drop tank to run G/GL at Bonneville. Sharon will probably be driving so I'd rather not have to worry about shifting along with driving and watching everything that she has to do. It would probably give her a better shift and less chance of breaking the rear tires loose than a manual tranny. Since it will be a rear-engine vehicle, the shift linkage would be much easier with an automatic.

kb426 · February 08, 2007, 06:44:12 PM

Leon, you have valid points for using the c4. My question is, who has spin tested one past 10 grand? If you find some Ford drag racers, they may have an answer. My thought is: anything that is going to be spun to tremendous rpm should have the rotation parts magnafluxed. I'd build a full 1/4" plate scattershield for the trans but what if it explodes and locks up and puts her upside down? If it were me, I'm stupid enough to try about anything but I'd want to be sure if my wife was in it. I think you'll find the answer, maybe not here though. The only useless info I can offer is when a blown alky engine breaks and turns loose, before we had rev-limiters, they would turn 12000 rpm. The Lenco's didn't self destruct. I'm sorry I'm not much help.

ONE37TUDOR · February 08, 2007, 08:32:46 PM

Don't know about a C-4 but I ran a Powerglide for several years in a circle track car without a torque converter. The set up used a splined spool piece that that bolted directly to the crank shaft hub. It used a valve to dump pressure to act like a clutch.
If something like that could be done with the C-4 it would eliminate some of the RPM worry's? Then with an upgraded planetary set it should turn up past 10 k with little problem?
The problem then may be that the motor would turn up to fast to keep good traction and when you lifted a very high speed and low car weight it may lock the tires up? When I used this set up on a stock car I would use very little brake in the turns, without the flywheel the engine acted like a very good brake.
Scott...