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Re:Higher RPM upgrades?

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29 Nov 2022 16:02 #246151 by Vandoni
Higher RPM upgrades? was created by Vandoni
So, if I wanted to be able to rev the little M13A to higher RPMs reliably, what mods should I do?
I know these engines start to lose power over 5500 RPMs, or at least that's what I can feel while driving if I'm not mistaken, but I want to prepare the engine to be able to reliably be revved to 7000, any advice?

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29 Nov 2022 16:28 #246152 by DrRobin
Replied by DrRobin on topic Higher RPM upgrades?
Peak engine power occurs at 6,000rpm (peak torque at 4,100rpm) and the engine redlines at 6,500rpm. Once you pass peak torque the engine feels as though it accelerates slower, once you pass peak power you need another gear. I am not sure what you hope to gain by going over peak power (6,000rpm)?

Let's just say you do want to rev to 7,000rpm, you probably want to change the valve springs, possibly the valves and pistons, that always assumes HD versions are available. You might also need to adjust the timing to avoid pre-ignition.

Then you might find that the con-rods or crank are not really suited to rpm greater than 6,500rpm.

Note sure if the Jimny has a rev limiter, I did see one spec sheet that said 7,000rpm, so you might need to raise this up a bit.

If it was me I would be happy to stick with changing up 6,000rpm and save a lot of money/blown engine.

2011 Blue Jimny SZ3, Hankook Dynapro/Maxxis Worm-Drive, BB Classics BB6 Sports Seats, Radius Arm protectors, Android Head, DAB, 360 Camera, TPMS, K&N, Bosch Aerotwin, boot light, parcel shelf, boot box, dash box, Osram Nightbreakers, CTEK Battery Sense, Front & Rear Recovery points, CB Radio.

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29 Nov 2022 16:33 #246153 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
For what I've seen, you're right, and the engine cuts spark at 6750 if I remember correctly, but I'm a sucker for high revving engines and since I'm trying to make my little car into a stupid replica of an old n/a rally car, I'd love to have the engine rev higher.
I already knew about springs but never thought about the crank not being able to sustain those levels of abuse

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29 Nov 2022 16:59 #246155 by DrRobin
Replied by DrRobin on topic Higher RPM upgrades?
I don't really know if the crank/con-rods will take the extra revs, it's just push the power/rpm above the rated nearly always results in reduced engine life, sometimes dramatic/sudden.

Rather than rev the M13A engine higher why not look for a M15a/M16a, that wil give you a good power increase?

2011 Blue Jimny SZ3, Hankook Dynapro/Maxxis Worm-Drive, BB Classics BB6 Sports Seats, Radius Arm protectors, Android Head, DAB, 360 Camera, TPMS, K&N, Bosch Aerotwin, boot light, parcel shelf, boot box, dash box, Osram Nightbreakers, CTEK Battery Sense, Front & Rear Recovery points, CB Radio.

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29 Nov 2022 17:04 #246156 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
I could get a 15 or 16 but I posed myself the objective of leaving the stock engine in the car, or at least not to swap it with a different engine type, even though one of the things I want to do in the distant future is to bore it out to 1.5 liters

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29 Nov 2022 18:25 #246158 by jackonlyjack
Replied by jackonlyjack on topic Higher RPM upgrades?
M15 & M16 look just the same as M13 (only difference numbers stamped on side)
Head is same on all 3 so just fit M16A ~100bhp 
OR spend 2.5k+ to gain 100rpm 
 

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29 Nov 2022 18:49 #246160 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
I could, as long as the "character" of the engine isn't too different.
I know that modding two very similar engines the same way makes them behave in a similar manner, but I really like my really small one and its quirky characteristics, also i know nothing about the m15 and M16 so I can't say anything about those right now

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29 Nov 2022 19:02 #246161 by jackonlyjack
Replied by jackonlyjack on topic Higher RPM upgrades?
1.6 just pulls better 
30mph 5th gear no vibration when pushing skinny pedal to the floor
I have 7.50r 16 (32")tyres fitted 
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29 Nov 2022 20:18 #246163 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
I looked around and an M16A goes for around 1500 € where I live, and i noticed it has vvt, which is good, and an electronic throttle body, which is dislike, I would very much prefer to keep the cable throttle I have with the 2000 m13a, is that possible in any way? Since I'll swap the engine in the future I might just put some money aside change the throttle too, or just put ITBs instead, as I already know where to find them

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29 Nov 2022 20:54 #246164 by Busta
Replied by Busta on topic Higher RPM upgrades?
Similar to all your other questions, my answer is much the same. Leave it alone! The standard engine will reliably rev to 6,750. You won't gain anything by trying to change that. As others mentioned, peak power is at 6,000. There is some merit to reving beyond that as the power doesnt fall away instantly afterwards and to get best performance you're aiming to achieve the highest average power. But by 6,500 it's falling away quick enough that it's time to shift up a gear.

The bigger engines use a longer stroke to give more power, and as a result they do lose the revvy nature of the 1.3.

Hows the driving practice going?
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30 Nov 2022 07:44 #246166 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
Yeah that's what I was afraid of, I like the engine being rev-happy and was worried the bigger ones wouldn't like high revs as much.
as for the practicing, I haven't been doing much off-road this month because I just had the new reinforced dampers installed to take care of my old dampers that were completely gone, but I'll see how I fare this weekend and see if the little pause had any effect on my training 
 

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30 Nov 2022 13:52 #246170 by fordem
Replied by fordem on topic Higher RPM upgrades?
As has been pointed out by many of the folks who responded, there is very little advantage to be gained by revving the engine to the existing redline & rev limiter, the power just isn't there, and you could probably make better use of what power there is by shifting earlier so as to keep the engine within it's power band.

It might be possible, if you're into engine modifications, to port match & polish the cylinder head, and perhaps replace the cam shafts and gain more power higher in the rev range, but that usually comes with a loss of power in the lower rpm ranges, and that is not necessarily a good idea in a 4WD vehicle that's going to be used off road.

I say, might be possible, because of a lack of knowledge about your particular engine - it is something that was very common in the days before variable valve timing became popular, and whilst a port & polish job might yield some benefit, variable valve timing allows the valve timing to be optimized at both ends of the rev range making custom camshafts less attractive. If your engine doesn't have VVT it might be something to think about.

Yes, it is fun to wind the engine up to the red line, but it's also a clear indication that the driver isn't using the power available effectively - I live within earshot of a local road that is often used on weekend nights by "street racers" and can tell by listening who knows what they're doing and who doesn't
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