Looking to more top speed in 3rd
10-19-2018, 08:37 PM
#11
I agree and disagree with your assessment. As someone who has run an F22 with an Ap1 ecu for a lot of years and done research over the years on the topic, I will tell you that the head of the F22 is the same rev limit capability as the F20, so yes you are correct there 9k+ rpm capable, however what the breathing limiting factor is with the F22 is the cam profile those head come with, which is more conducive to flow best within the stock F22 rev band, no surprise there as it wouldn't make any sense to do anything but that from the factory. The bottom end on the F22 can rev to 9k regularly, however it will shorten the lifespan of the cylinder bores due to the added side loading due to the shorter length rods, which puts these at a more severe angle during each revolution, ovalizing the bores quicker. The rods are strong so they can take the added rpm, but the added loading at that high an rpm will have a more rapid wear rate on the bores and may eventually on the main bearings. 8500rpm on the F22 is actually the equivalent piston speed of an F20. So the F22 is actually more conservative then it was built for compared to the F20, by 300 rpm. The F22 head has beefier valve retainers/keepers so in that way its actually an improvement to retain the valve at a higher rpm, but valve float likely still happens about the same rpm as I don't think any change was done to the valve spring weight. Really you don't want super heavy weight valve springs anyway as that just puts more pressure/wear on the cams and related components. Just go as heavy as needed to control the valves without float at the intended pm limit and not really go any higher then that. The heads flow the same on both f20/f22, its the cams that dictate the flow character difference.
Just wanted to kind of clarify on the subject for all those who find this thread and are interested.
Just wanted to kind of clarify on the subject for all those who find this thread and are interested.
The valve stems and springs are big issues because a dropped valve or broken off valve head will hand grenade the inside of the engine. The broken piece hammers the piston until it breaks, meanwhile sending pieces of the piston through the intake into the other cylinders. Eventually, the piston fractures sending the rod through the block wall at which point none of the long block components other than the cam, rockers, and cam gears are probably salvageable. One guess how I know.
That valve and valve spring failures seem rare may reflect the quality of the parts Honda used (this was a flagship product and a very high rev limit for its time), the profile of the cam, and the tendency of many owners not to run the engine at consistent high revs. There seems to be more talk of 10k-11k rev limits on the forced induction forum than elsewhere.
But breathing above 8200 rpm is probably not an issue here. As I understand the problem, it is topping out in gear just before a corner and bouncing off the rev limiter. Happens in autocrosses all the time, but there in 2nd gear. At non-competitive track day, simply raising the limit would allow avoiding the rev limiter, even if the acceleration was less than if it was upshifted. Shift lights could be added that indicated the right point to shift even if the engine allowed going beyond that point.
Cheapest, quickest fix...and without affecting the handling...raise the rev limit.
10-20-2018, 02:38 AM
#12
So I have an 07 and I am looking to get a little more speed in 3rd. I did my first track day and noticed that in a couple turns I was bouncing off rev limiter before I had to brake but it wasn’t enough to shift up then down shift. I’m just wondering what the easiest way to get a little more speed out of 3rd would be. Tune to 9000rpm? Rear gears? Any input or tips or advice would be great.
If you have low experience and are not fast and also not competing, just leave it. You will get much faster with time and you speeds in each corner will change based on that. Also, don't change your gearing just for one track.
Sometimes you have to take a sacrifice for one track or one corner for the benefit of others in terms of gearing.
10-22-2018, 03:33 AM
#13
How much experience do you have? How fast are you?
If you have low experience and are not fast and also not competing, just leave it. You will get much faster with time and you speeds in each corner will change based on that. Also, don't change your gearing just for one track.
Sometimes you have to take a sacrifice for one track or one corner for the benefit of others in terms of gearing.
If you have low experience and are not fast and also not competing, just leave it. You will get much faster with time and you speeds in each corner will change based on that. Also, don't change your gearing just for one track.
Sometimes you have to take a sacrifice for one track or one corner for the benefit of others in terms of gearing.
10-22-2018, 09:13 AM
#14
i have a lot of experience in autocross and one track day but i was about 20 seconds off the track record in my class (1.18 is the record) so i know i definitely need more practice. the track is right down the road from my house so i plan to run there a lot. one of the corners i was consistently bouncing of rev limit in third i know i could carry more speed out of the corner before and that will come with seat time but one of the other corners i feel (and so does my instructor i had) i was nailing but i think shifting into 4th then back to 3rd would slow me down not help. my main thoughts for trying to get a little more out of each gear was to increase the rpms and if that still doesn't do it i would look into the cost of gears for the rear end or buying a separate rear end and build it with gears. the increasing rpms will probably be the cheapest and easiest (07) and i would like to get it on the dyno anyways.
More then likely, your corner exit from the previous corner can get significantly faster making 4th more viable into the next turn. Either way, 20 seconds is an eternity on any track especially a shorter one. Just continue to focus on your driving getting faster and don't touch the car.
10-24-2018, 09:24 AM
#15
Don't take this the wrong way because it isn't meant to be but if you are 20 seconds off pace on a sub 1:30 track then you should not be thinking about modifying anything on your car other then safety related equipment.
More then likely, your corner exit from the previous corner can get significantly faster making 4th more viable into the next turn. Either way, 20 seconds is an eternity on any track especially a shorter one. Just continue to focus on your driving getting faster and don't touch the car.
More then likely, your corner exit from the previous corner can get significantly faster making 4th more viable into the next turn. Either way, 20 seconds is an eternity on any track especially a shorter one. Just continue to focus on your driving getting faster and don't touch the car.
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