summitrider2012

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.

s2000ellier

raise rev limiter to 8800

Chibo

Ignore it for now because you're going to learn to carry more speed through corners than before and be in 4th where you're complaining about banging the limiter in 3rd.

BoboTheMonkey

^Agreed on this. I have wanted to raise my rev limiter a bit though, but have an 05 so that isn't an easy option. Certainly would not go to 9000 unless you have everything built to withstand that. Live with what you've got unless it purely a race car that you don't care if it explodes.

summitrider2012

s2000Junky

Bump up the rev limit to 8500rpm - which is completely reasonable/safe for a stock engine long term. Can also run a 275/40 out back to increase your gear ratio. This will effect all your gears of course, not just 3rd.

Sylvain2000

Probably not the nest option but the AP1 tranny as longer 1-2-3-4 gears.

Also while your learning to get it that specific curve faster you might want to short shift the 4th gear instead of bouncing that rev limiter on the 3rd gear. This way you will be able the carry more speed trough the corner

BlueBarchetta

DavidNJ

I vote for changing the rev limiter. People up them to 8500rpm all the time...it is de riguer for Solo II STR. However, I'm pretty sure you would be fine with 9000 or even a bit above that. The only issue would be valve springs and maybe the valve stems on your 11-year-old car.

The top end of the AP2 is the same as the AP1. There is nothing in the bottom end that can't handle 9000rpm with the AP2 stroke. As far as I can tell, the rev limit was dropped for the AP2 because the breathing wasn't increased to handle the higher revs.

However, valve springs and valves are a wear item, especially if they spend a lot of their lives on VTEC (a more aggressive cam profile) and at higher revs (more cycles). In many forms of racing valve springs are checked for spring rate on the head in the car and the springs changed without removing the head. This tool lets you remove the spring, you can hold up the valve with compressed air or my feeding a cord in the cylinder then raising the piston so it holds up the valve: https://www.hptautosport.com/collect...-k24-f20c-f22c. I haven't seen a tool to measure the valve spring rate on the Honda head, but there are many available for OHV V8s: https://racetoolsdirect.com/product-...pring-testers/

s2000Junky

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.