Raising Rev Limiter
#1
Elite Member
Thread Starter
iTrader: (17)
Join Date: Aug 2007
Location: Knoxville, TN
Posts: 2,949
Total Cats: 183
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I'm curious what you guys are revving your car to and what needs to be done in order to safely raise the rev limiter.
I've always stuck with a 7000-7200 limiter on my car. Are people going a bit higher than that on stock motors? Is there a point at which the valves/springs start to become an issue? Or a point the stock oilpump starts to crap out?
I know some of the built guys are revving up to 8000, but I seem to remember others offering some pretty strong opinions against going over 7400-7500. I can't find much on the site discussing any practical limits.
I've always stuck with a 7000-7200 limiter on my car. Are people going a bit higher than that on stock motors? Is there a point at which the valves/springs start to become an issue? Or a point the stock oilpump starts to crap out?
I know some of the built guys are revving up to 8000, but I seem to remember others offering some pretty strong opinions against going over 7400-7500. I can't find much on the site discussing any practical limits.
#9
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
https://www.miataturbo.net/showpost....4&postcount=38
These numbers will sound conservative, but I am a track junkie and my cars see more abuse in a single 20 minute session than your average street car sees in a month of commutes. You can probably exceed these numbers in a street car and be OK in the short term, but if you want long term reliability or track reliability, I'd stick to my numbers.
Revs:
Stock rods will not accept anything past about 7800rpm without stretching. Spec Miatas are documented to stretch rods on single sub-8000rpm overrevs. If you push past 7500 on a regular basis, you need forged rods.
Stock oil pump gears have a generally accepted limit of 8000rpm due to crank harmonics. Push past that (or run at 8k for a long time) and billet gears are strongly recommended.
OEM valvetrain is good up to the ~7800rpm mark. At a certain point, the valves will start to float, which means you either need stiffer springs or lighter retainers.
Making power at 8000rpm is hard. You need a huge centrifugal blower, a lot of port work, big cams, or a combination of at least two of those things. Most people do not spin the motor this hard.
FOOTNOTE: VVT users MUST adhere to a strict 7400rpm limit due to an intake cam harmonic. Change the intake cam and you may press past that limit.
Revs:
Stock rods will not accept anything past about 7800rpm without stretching. Spec Miatas are documented to stretch rods on single sub-8000rpm overrevs. If you push past 7500 on a regular basis, you need forged rods.
Stock oil pump gears have a generally accepted limit of 8000rpm due to crank harmonics. Push past that (or run at 8k for a long time) and billet gears are strongly recommended.
OEM valvetrain is good up to the ~7800rpm mark. At a certain point, the valves will start to float, which means you either need stiffer springs or lighter retainers.
Making power at 8000rpm is hard. You need a huge centrifugal blower, a lot of port work, big cams, or a combination of at least two of those things. Most people do not spin the motor this hard.
FOOTNOTE: VVT users MUST adhere to a strict 7400rpm limit due to an intake cam harmonic. Change the intake cam and you may press past that limit.
#10
Elite Member
Thread Starter
iTrader: (17)
Join Date: Aug 2007
Location: Knoxville, TN
Posts: 2,949
Total Cats: 183
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I may bump the rev limiter up a couple 100 and see how she does. After looking at my dyno, running above 7500 on my current setup would be pointless.
Seeing that 300hp "limit" on stock pistons is a bit scary, but it doesn't seem like too many people are dumb enough to install rods and not pistons. Hopefully their a little stronger than we're assuming, mine seem to be holding up well so far.
#11
Elite Member
iTrader: (2)
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,682
Total Cats: 130
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Bah.
not every miata is driven as EXTREMELY as all these track "gods". I have revved to 8000rpm for 10k miles and my motor is fine. I drive on the street. Savingtons VVT data is based on a limited sampling.
Even if you have a power sag over 7000, if you are makig more power at 8000 than at ehatever RPM you drop to post-shift, having the extra rpms in boost for a bigger turbo can make a significant positive impact in driveability.
not every miata is driven as EXTREMELY as all these track "gods". I have revved to 8000rpm for 10k miles and my motor is fine. I drive on the street. Savingtons VVT data is based on a limited sampling.
Even if you have a power sag over 7000, if you are makig more power at 8000 than at ehatever RPM you drop to post-shift, having the extra rpms in boost for a bigger turbo can make a significant positive impact in driveability.
Thread
Thread Starter
Forum
Replies
Last Post
StratoBlue1109
Miata parts for sale/trade
21
09-30-2018 01:09 PM