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Re:Higher RPM upgrades?

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30 Nov 2022 14:39 #246172 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
Yes, I see what you're saying, a ported head is something my mechanic hinted at when talking about making more power, and I was also thinking about a set of cams, and these mods would be fitting because I plan on using the little Jimny as a rally car, not as a normal offroader.
also, I'd prefer to keep the engine vvt-less as to keep the head as mechanically simple as I can, not caring about the economy and power advantages.
I'm still a little confused about my engine's powerband, I think the mods I did shifted it in some way, and I need to study it a little more before I can make adjustments accordingly

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30 Nov 2022 15:18 #246174 by DrRobin
Replied by DrRobin on topic Higher RPM upgrades?
You might want to check this out about a Jimny prepared by Dave Marsh Racing

www.superproeurope.com/news.read.cfm?articleid=61

and this one top gear.

www.topgear.com/car-news/the-great-outdo...y-go-desert-rallying

2020 blue SZ5
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Northumberland Jimny Blog

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30 Nov 2022 15:48 #246175 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
Yes, I saw that article and it is pretty interesting, and also goes to show that the little Jimny can become a rally car with some minor mods, which is something I like very much

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30 Nov 2022 20:04 #246176 by Lambert
Replied by Lambert on topic Higher RPM upgrades?
As one of the very small minority of Jimny drivers with actual seat time circuit racing a Jimny I think you are looking in the wrong place for gains. The m13 is a very entertaining engine and is good at making you think all sorts of performance is happening because it's so free and quick to get up the rev range but in reality it is mostly just noise. That is not to say you can't make an m13 Jimny relatively quick but that is done by working to conserve momentum. Inn other words once you get it moving don't let it slow down. This is achieved by having very controlled suspension and effective management of the heat generated by the brake system. On Dreadnaught, my last Jimny, I had big bore sports dampers from trailmaster, custom lower stiffer road springs and ebc brake components and 5.1 fluid and relatively sticky road tyres. Add all that to loads of seat time enough to be totally comfortable with how the car would react and I was not only able to hang with faster cars but embarrass a few along the way.

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30 Nov 2022 20:30 - 30 Nov 2022 20:50 #246177 by Vandoni
Replied by Vandoni on topic Higher RPM upgrades?
Oh, absolutely, I use that style of driving too when I'm on tarmac, keep momentum and brake only the necessary, if at all.
I have upgraded my dampers a week ago, and I have to say, the car feels a lot more planted now, at least on the road, I still have to test it off-road, since my dampers should shine there.
Talking about the brakes though, I was driving today and decided to push a fair bit, just to have some fun, and after a while, I noticed that the brake pedal felt strange, it was like it had two "steps" (?), it was soft for a little bit of travel, which is normal for my car, then harder like if it had actually began biting, but with not that much braking happening, and then soft again for a little bit before actually getting harder and starting to brake effectively.
The thing is, I almost hadn't braked before that, but I pushed the engine a lot, and passed on some little rocks and animal residue on the way, could it be that my brakes are on their way out? Which is probable since my disks are not thick at all, or could the gunk be causing those problems?

Also I was thinking about my exhaust, I read around the forum that these engines really love getting a better flowing intake and exhaust, and a few months back I got a sportier muffler to replace my rusted stock one, I was thinking about taking off my cat and straight piping that part of the system, would there be any way to do that without having to retune the car because of the sensor?
Last edit: 30 Nov 2022 20:50 by Vandoni.

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30 Nov 2022 21:09 #246178 by DrRobin
Replied by DrRobin on topic Higher RPM upgrades?
The post CAT sensor doesn’t normally change the mixture, it’s just there to check that the CAT is working and shows a fault if it doesn’t get a good reading.

The pre-CAT sensor on the other hand does fine tune the mixture, in conjunction with the Mass Air Flow sensor.

So usually you can just disconnect the post CAT sensor, or perhaps put a bypass plug in.

2020 blue SZ5
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Northumberland Jimny Blog

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30 Nov 2022 23:10 #246179 by Old Neil
Replied by Old Neil on topic Re:Higher RPM upgrades?
Sorry I Don't know if you have done this already
Remove viscose fan and fit thermo fan, you could even use Davis Craig electric water pump they sell a controller for electric water pump and thermo fan
I found out too big an exhaust will reduce power

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01 Dec 2022 05:26 #246180 by Lambert
Replied by Lambert on topic Re:Higher RPM upgrades?
For reference and to further make the point, Riccy of this parish has managed to get a 1.8 version of the engine and even with extensive work including throttle bodies and a stand alone ECU he is only making around 130 hrsprs. Ok he is looking for torque not power but still an extra 40 hp from an additional 500cc and significant modifications kinda suggests that these are already very efficient engines that don't really have much more to give.

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01 Dec 2022 10:44 #246181 by Vandoni
Replied by Vandoni on topic Re:Higher RPM upgrades?
Ok I understand, so unless I use forced induction or put some extensive mods I won't be able to get that much more out of the engine, well it's ok.
as for the cat, I'll see what I can do about the second sensor, hoping it's as you guys say and it doesn't regulate the mixture 

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01 Dec 2022 11:59 #246182 by DrRobin
Replied by DrRobin on topic Re:Higher RPM upgrades?
See this article about fitting a deCAT exhaust (and what to do with the second sensor).

caracaltech.com/articles/article/61483ca32325529176db54cc

Robin

2020 blue SZ5
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Northumberland Jimny Blog

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01 Dec 2022 12:03 #246183 by DrRobin
Replied by DrRobin on topic Re:Higher RPM upgrades?
If your de-CAT pipe has a hole for the second O2 sensor, then use something like this to move the second O2 sensor away from the gases and keep the ECU happy.

mtcmotorsport.co.uk/products/mtc-motorsp...en-sensor-boss-m135i

Alternatively, I have seen some plugs that give a false sensor reading, or just disconnect it, it will throw up an error code and you might get a CEL on.

Robin

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Ex 2011 Blue Jimny SZ4
Northumberland Jimny Blog

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01 Dec 2022 16:37 - 01 Dec 2022 16:38 #246187 by Vandoni
Replied by Vandoni on topic Re:Higher RPM upgrades?
So if I move the sensor from the original cat to the catless pipe it'll give me a CEL?
​​​​​​But would the CEL put the engine in some kind of safe mode or would it still run the same?
Last edit: 01 Dec 2022 16:38 by Vandoni.

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