high rpms in 5th

[murda_9]

i have a 93 mx3 v6 and my idle is good but when i drive my rpms are high like on the high way going 80- 100 kms my rpms are at 3 - 4000 it sounds like my engin will blow can any one help me find out what it is thank you maybe its suppose to rev that high but it dosent sound good

[DimaK]

i believe that's normal for K8, dropp a DE or a ZE in it with probe/mx6 tranny, then at a 100km/h youll be revving at 3KRPM

[Nd4SpdSe]

Ya, at about 120km/h I'm reving around 4000. Don't worry, it's a common question. I do like the gearing with that gearbox an a ZE, being in the highway you can just punch it and go.

[Mooneggs]

yep and then you hit your VRIS points shortly after that FTW

[IrishNinja]

I have the same problem but I don't think it's normal because when I first got the car it would only do it in high 5th. But not I hear it in all the gears at a high rpm (3.4-4k). It sounds like the engine's spooling up. Could it be a vacuum leak possibly? I don't know what it is either and I would really like to fix it.

[tehbrookzorz]

I have the same problem but I don't think it's normal because when I first got the car it would only do it in high 5th. But not I hear it in all the gears at a high rpm (3.4-4k). It sounds like the engine's spooling up. Could it be a vacuum leak possibly? I don't know what it is either and I would really like to fix it.

If the revs are higher than normal (let's say normal is 3,000rpm at 100km/h) then you might have a slipping clutch.

[IrishNinja]

Would that account for the spooling sound? When I'm in 5th, both the tach and the speedo needles are fairly oriented the same. I don't know if that's normal for an 92 or not.

I have the same problem but I don't think it's normal because when I first got the car it would only do it in high 5th. But not I hear it in all the gears at a high rpm (3.4-4k). It sounds like the engine's spooling up. Could it be a vacuum leak possibly? I don't know what it is either and I would really like to fix it.

If the revs are higher than normal (let's say normal is 3,000rpm at 100km/h) then you might have a slipping clutch.

[tehbrookzorz]

It would provide a reason for your "spooling" sound, but the tach would climb disproportionately from the speedo.
I'm not sure spooling is the best word. It might be throwing people off, since spooling is best used tin the automotive world as the sound a turbocharger makes.

[IrishNinja]

Well when I climb past 3k in 5th the pitch and intensity progressively increase, so that's why I said it was a spooling sound. I checked today, in 5th going 100km/h my tach reads 3200 rpms. Is that higher than normal?

It would provide a reason for your "spooling" sound, but the tach would climb disproportionately from the speedo.
I'm not sure spooling is the best word. It might be throwing people off, since spooling is best used tin the automotive world as the sound a turbocharger makes.

[RX8SE3P]

3200 -3500 sounds about right for the 30x/MX-3 when going 100-110 KMPH. Unfortunately it doesn't make it the most quiet or fuel efficient car if you wanted to cruise around @ 130KMPH.

Also, if you put a gearbox in with lower ratios, you'd rev far less but the car would go absolutely nowhere since a stock MX-3 basically has no torque LOL.

However.... slotting in a KLDE/KLZE and putting a gearbox from the MX6 or 626 would make it rev a little less but still have plenty of power and still be able to cruise @ 120+KMPH.

Also, I can hear a "spooling" type noise in my MX3 too when I rev considerably high - 5000+ RPM. It's not that loud though, I car hardly hear it above my exhaust lol. Sounds more like the car is sucking in air faster, which is most likely what it's doing.

[hgallegos915]

lol i always see my sel hitting 6k in my car every day lol

as far as hwy speeds, yeah its always at around 3k rpms. i not higher.


the car becomes very fuel effecient at hwy speeds by the way.

around 30 miles per gallon. Not bad for a v6 2.5!


dunno about the k8 tho

[RX8SE3P]

City driving would be far more efficient than highway, it's just that city is always stop start and highway is non stop.

If you drove @ like 60-80KMPH non stop, your fuel economy would probably be around 5-6 litres per 100kms. So technically highway driving is far less efficient, it's just because you never stop which makes you get more mileage. But which city does not have traffic lights and places you have to stop

I'd imagine the 2.5L would almost be able to beat the 1.8 for fuel economy on the highway. Simply because it wouldn't be stressed going up inclines or having passengers like the 1.8 would. The KLZE @ 3000-3500rpms would probably be making more power and torque than the K8 would @ 6500rpms lol.

I wouldn't mind seeing a dyno chart for both so I could compare

[fowljesse]

My ZE gets about 29 mpg, and my K8 gets about 30. The ZE peaked at 31 on a road trip, and the K8 peaked at about 35. The K8 has 130,000 miles, and the ZE was completely rebuilt about 7,000 miles ago. They both seem to be most efficient at about 68 mph. If the engines were both new, and in the same car, the difference would be bigger, because the ZE is lowered (less wind drag), and weighs a little less.
The formula for the best MPG speed is: The closest you can get to the torque peak, in the highest gear, before wind resistance becomes too great. This is at about 60 mph, on most cars. Our cars have a low Coefficient of drag (GS has about the same as a Porsche Boxster, when lowered).