what is the highest rpm that is safe for our cars?

[madforce10]

at the last autocross i was running out of gear in second and i was topping out at 58mph at 5800rpm. im just wondering what is the highest rpm i could run with our breaking anything in my engine. im wondering this so i could gain a couple mph in the slolem. my camaro is a 5 speed with 3.42 gears if that helps any one. ideal top speed for autox in second is 60-65 and that is what im trying to reach.

[flamingchicken]

Re: what is the highest rpm that is safe for our cars?

I know people on here often tune for 6000 rpm, and some 6200, but i would think that would be a bit high for a stock valve train.

[techsan23]

Re: what is the highest rpm that is safe for our cars?

There is no guarantee that your engine will not break at any rpm. Without looking at a dyno sheet I think I remember the power curve dropping off fairly noticeably after 5600 rpm on a stock engine. At 5800 there is a good chance you are starting to float valves. With an aftermarket cam, stiffer valve springs, removed or disabled balance shaft and raised rev limiter you could pull 6500 rpms.Not sure what speed that would put you at.

[ssms5411]

Re: what is the highest rpm that is safe for our cars?

I know on a 2000 Firebird I just tuned a few months ago stock was set at 6000 rpms. I set it at 6200 rpms since he did a cam and spring swap and it pulls pretty good.

[madforce10]

Re: what is the highest rpm that is safe for our cars?

im probably just going to set the limiter to 6000. im not looking for a hard pull im just looking for a few extra mph so i don;t loose time up shifting and down shifting at the very end of a slolem. and i am actually talking about riding the limiterfor 1 maybe 2 seconds. if im hitting it longer than that i need to change into third.

[madforce10]

Re: what is the highest rpm that is safe for our cars?

this video is what im talking about he rids the limiter at 25 seconds in the video.
http://www.youtube.com/watch?v=D-6Tk...6&feature=plcp.

[2.8 Bird]

Re: what is the highest rpm that is safe for our cars?

High RPM is what destroy most engines. I say focus more on building high HP and TQ than how to get more RPM.

[WarShrike]

Re: what is the highest rpm that is safe for our cars?

It is only safe to spin an L67/L32 to ~6300 rpm on a stock balancer. Going over that can cause bearing failure, flex plate failure and power loss due to harmonics.

That's what I've found.

[madforce10]

Re: what is the highest rpm that is safe for our cars?

That's what I've found.
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thank you thats what i was looking for.

it not a matter of power for me but more a matter of time and speed of having to up shift and down shift.

[87SC/SS]

Re: what is the highest rpm that is safe for our cars?

That's an S2000 in the video, those have a pretty high redline - like 8k I think. If I remember correctly - my buddy's S2000 pulled pretty hard from around 5500 all the way to 8000 and wasn't too shabby below 5500 either. That's VVT for ya.

You may want to consider re-gearing the rear end to bring that speed into your rpm range. Either gear up (numerically) to run the course in third gear or down to run it in second. You'll lose some acceleration by gearing down but you won't have to shift - or worry about spilling parts on the track.

The other thing you might consider is playing with tire sizes. Factory tire height is about 25" - getting slightly higher or lower profile rear tires can affect rear gear ratio without having to change out gears. A 1 inch taller tire for example drops a 3.23 ratio to 3.11. That little change in ratio could drop your rpm enough to keep you in power band without risk of damaging your motor. Only real downside is some more sidewall flex.

Here's a calculator: http://www.ramblerman.com/blazer/gearcalc.htm

Let me finish by saying the RIGHT way to do it would be changing the rear gears.

[WarShrike]

Re: what is the highest rpm that is safe for our cars?

Haha Honda's are designed to be revved to the sky.

If you're running stock intake/heads, going over 6 grand is useless. You can see the airflow start to get really screwy at higher rpms/lift with stock intake/heads.

You don't need to rev it past where you're making power as well, it's just wasted effort.

[madforce10]

Re: what is the highest rpm that is safe for our cars?

well the tires im planning on running with the wheels might provide a little shorter gearing but im still not ruling out putting the car into third. i just recently changed from a taller gear set, since i used one of those calculators to determine that the 3.42 gears i was running would be closer to ideal gearing. i just really wanted to see what type of rpms i could pull with this engine in stock form. not really worried about power since it is limited anyways. i i think the general consensis is nothing over 6000 rpm.

oh by the way s2k first gen rev to 9000 and second to 8000.

and just found one of those speed readers close to my house so i can see if im getting a false reading from my speedo from hard acceleration. like if the dampening of the gauge is to slow for my actual acceleration. cause i did notice a difference one time.

[madforce10]

Re: what is the highest rpm that is safe for our cars?

just did some more calculating for my competition in stx.
top two car in stx are the mazda rx8 and the e36 325i top speed in the mazda in second is 62 mph and the bmw is 65 (chipping that car bumps up the rpm range to 6500 to 7000rpm)
if i set my limiter at 6000 then my top mph is 61. if i go back to 3.23 gears in the rear my mph is bumped up to 66 at 6000. so my gearing currently is just under par for this class but i gain the acceleration needed to keep up with the bmw.

i have based this off of comparisons of my brother's 325i which is slightly above the rules in stx.

plan of action currently is to keep everything the same for now. next national style event compare speeds with other cars and if need be short shift into third. next three events are slower speed event due to site restrictions.

[DAS BOOT]

Re: what is the highest rpm that is safe for our cars?

Have you considered a different tire, gear, rev limiter?

I forgot what I bumped it to, but on my old 2k, I bumped it so I could roll through the traps in 3rd gear with 3.42s. I never got a clean run before my car broke, but I think I had a good low 14 run.

[dmw319]

Re: what is the highest rpm that is safe for our cars?

9583... or so