Stroking and redline
Joined: Mar 2001
Posts: 37,305
Likes: 18
"Safety margin".
I think Honda wanted to maintain reliability. It's not a matter of "affecting" the redline. Your Toda example is simply removing some of the margin of safety that was already built in. I mean, technically, the pre-'04 cars "could" go to 10,000 rpm by removing the rev-limiter but then, your safety buffer is virtually gone. Is that what you want?
I think Honda wanted to maintain reliability. It's not a matter of "affecting" the redline. Your Toda example is simply removing some of the margin of safety that was already built in. I mean, technically, the pre-'04 cars "could" go to 10,000 rpm by removing the rev-limiter but then, your safety buffer is virtually gone. Is that what you want?
Registered User
Joined: Oct 2003
Posts: 327
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From: Morganton
I personally do not like the idea of a 2.2 reving any higher than 7000 rpm's. There is not much you can do to help the motor to rev to the stock 9krpms, and if you do then the reliablity of the car goes right out the window along with your money.
The example i use with my friends is a 1.5 jdm vtec motor. There is alot of guys that come to me and want me to build these motors. I leave them the stock stroke of 1.5 add some good pistons and valve train parts, and we have succesfully reved these motors to 11k rpm's. But with a bigger engine like a mustang 5.0 there is so much stroke you would be lucky to see 5k rpm's.
The example i use with my friends is a 1.5 jdm vtec motor. There is alot of guys that come to me and want me to build these motors. I leave them the stock stroke of 1.5 add some good pistons and valve train parts, and we have succesfully reved these motors to 11k rpm's. But with a bigger engine like a mustang 5.0 there is so much stroke you would be lucky to see 5k rpm's.
Registered User
Joined: Jul 2002
Posts: 1,918
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From: Ottawa
Basically, the longer the stroke at the same revs = more acceleration forces on components = more wear and stress on components. So that means all things being equal stroked engines with the same redline will have to be rebuilt more often. If that increased maitenance is ignored, it could result in non-catastrophic failures, like spun bearings, blown rings or really bad stuff like breaking rods throught the block.
Non-racecars have warrantees which Honda designs so that under "normal" operation a high percentage of the engines will not fail. So, with the stroked 2.2 Honda ran the numbers and decided that to maintain the same survival % required a reduction of redline. Toda is designing aftermarket racing parts. They give no or limited warantee, so really don't have to worry about repaying warantees, which allows them to be more aggressive with their parts.
That being said, you can design the bottom end to increase reliablity allowing for more revs, but that is getting into some real mechanical engineering (i.e. $$$$$$).
Non-racecars have warrantees which Honda designs so that under "normal" operation a high percentage of the engines will not fail. So, with the stroked 2.2 Honda ran the numbers and decided that to maintain the same survival % required a reduction of redline. Toda is designing aftermarket racing parts. They give no or limited warantee, so really don't have to worry about repaying warantees, which allows them to be more aggressive with their parts.
That being said, you can design the bottom end to increase reliablity allowing for more revs, but that is getting into some real mechanical engineering (i.e. $$$$$$).
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Joined: Jun 2003
Posts: 1,557
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From: Addison, TX
One of the main factors that can do damage in the long run is the balance of the motor. More stroke=a longer up and down motion. Which also equals more side to side motion. The farther the crank is throwing the rods sideways, the more vibration a motor will have. The more vibration it has and the more wear you will have. The main bearings will probably be the first to crap out with the extra vibration.
The only way that cars such as F1 can rev to 12 to 15k rpm is because their motors are balanced nearly perfect. So the vibration is very very low. This goes for everything they use that rotates. But this is also the reason that one car costs several million dollars. A turbocharger that is for a race application costs upwards of $10,000. And they will use probably 10 turbos per season totalling $1,000,000 in turbos alone.
Anytime the components of a machine are designed with tollerances that low, the price skyrockets. Look at components on rockets and the space shuttle. A compressor for their rocket engines will cost several million dollars just for one. Their tollerances are in the 10,000ths or 100,000ths.
The only way that cars such as F1 can rev to 12 to 15k rpm is because their motors are balanced nearly perfect. So the vibration is very very low. This goes for everything they use that rotates. But this is also the reason that one car costs several million dollars. A turbocharger that is for a race application costs upwards of $10,000. And they will use probably 10 turbos per season totalling $1,000,000 in turbos alone.
Anytime the components of a machine are designed with tollerances that low, the price skyrockets. Look at components on rockets and the space shuttle. A compressor for their rocket engines will cost several million dollars just for one. Their tollerances are in the 10,000ths or 100,000ths.
