can a 2.4 iVTEC be remapped


Wrench Pro
Accord 2.4 iVTEC
Hi, I have an Accord 2.4 iVTEC.

The 2.4 only revs to 7k rpm, is it just a bigger version of the engine in the Civic Type R which revs to 8k rpm, and can the 2.4 be easily remapped to take it to 8k ?
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Is it a single or twin cam ?
If its single thats probably why the engine revs slower.
In this case although it can undoubtably be remapped for more power it probably cant be remapped for more revs
If its a twin cam then higher revs should be possible but you may need to change quite a bit first.
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Label on the bulkhead says its a K24A3.
The engine cover says i-VTEC 2.4 DOHC.
I undertand that the Civic has the K20 (2 litre), which I presume is also VTEC DOHC

My questions are:
(i) why does the K24 in the Accord rev less than the K20 in the Civic Type R ?
(ii) I've seen info where the K20 in the Civic is more BHP as standard than the K24 in the Accord as standard, but not sure.
(iii) What changes will I need to let it rev higher, surely there is a setting in the VTEC engine map that can be changed ?
(iv) I am assuming that by getting higher revs I will be able to get more power (assuming no drop in torque - its a VTEC) than by other changes in the engine map without increasing revs
(v) finally I've been googling and cannot find any re-mapping companies that specialise in petrol non-turbo Honda engines, anyone know of any ?

bye for now
The "Vtec" is just an engine design

Although it is a very good system it is not why it revs highly. It is a design that helps but it is not the reason nor is it the answer to everything .

Also your assumption that extra revs mean more power without loss of torque doesnt follow either Im afraid .

The R revs higher and produces amore power because it has been tuned to a much higher level with different cams valves etc etc .

So while it may be the same basic engine design as yours untill you uprate the relevant engine bits your engine will never rev like an R .

That doesnt mean you cant improve thing by mapping - you can , just not to the level of an R
Also your assumption that extra revs mean more power without loss of torque doesnt follow either Im afraid

hmmm not sure why you say that, look at the formula ....
horsepower = rpm x torque / 5252 where torque is in imperial units

So if there is no loss of torque, then if the revs can increase then the result is more power.

This may not mean higher speed since there is no increase in torque, but it will mean increase in acceleration in the lower gears, because the engine has a longer reach in the lower gears i.e. if no decrease in torque then it will be possible to reach a higher speed in lower gears, and the engine will momentarily produce higher powers in those gears.

My car will reach speeds as follows, obviously I tested this in Germany :lol:
On the speedo:
1st = 35 2nd = 60 3rd = 90 4th = 120 5th = 150 (downhill)
True speeds by satnav:
1st = 33 2nd = 57 3rd = 85 4th = 115 5th = 142 (downhill)
On the flat in 5th it typically reaches a true speed of 130 in 5th.

So I was simply hoping that there was an easy way to increase revs from 7k to 8k without reducing torque, which would mean true speeds as follows:
1st = 38 2nd = 65 3rd = 97 4th = 130 5th = 162 (behind a WRX)

Which would obviously mean much better straightline acceleration, which is all I want (I don't want a higher top speed and I don't want to go round corners more quickly).

But your point about i-VTEC puzzles me, what is the point of i-VTEC ?

bye for now
The Type R engines are balanced and therefore capable of holding higher power.

Rather than increase the RPM range i'd suggest mods that improve peak power from about 3000rpm. A 2 to 1 exhaust header, sport cat, and modified intake manifold and ported head would be my recommendations.
Hi Wayne, I have never modified an engine before, but I do fully understand how engines work. My background is control systems and a long time ago I worked on intstumentation systems for engine test beds, including hydro and electric dynos.

I have tried Google to find any companies that specialise in re-mapping of Honda petrol VTEC engines, unfortunately most seem to now specialsie in re-mapping of Diesel engines.

I am sure that it should be possible to re-map the engine, but I want it done by someone who knows how to re-map VTEC petrol engines. I suspect that it would be possible to change how, and when, the VTEC engages. This might give a slight uplift in torque and also a higher redline.

These are the figures for the engine:
Power: 189 hp (140 kW) @ 6800 rpm
Torque: 164.5 ft·lbf (223;N·m) @ 4500rpm
VTEC Engagement: 6000rpm
Redline: 7200rpm

I have not seen a torque curve for the engine, it feels as though it does not droop away after 4500 and hits the redine without warning if not looking at the rev counter.

If I am correct, then a re-map to 8000 should give a longer reach in lower gears as I mentioned earlier, and otherwise it will not affect the engine's life because it will not be spending a long time at those increased loads.

Having the head ported and a modifed intake manifold and exhaust sounds over the top to me, and I don't understand how that would help without cam changes in an ordinary engine. If I am correct, Honda simply kept the revs to 7200 to give the engine a very very long life. I mean, the car is now over 6 years old and is not worth much more than £3K, it's really aimed at a different market than me, but I've had it for 5 years and I don't want to spend a lot on it or sell it.

To conclude, I am sure that there are more changes possible in the mapping as it is a VTEC with "fly-by-wire" so the ECU can map throttle opening and cam opening angles and engagement of higher lift, as well as the bog-standard ignition timing and fuelling which non-VTEC ECUs can do.

Hope this helps, but note that I am not an expert in these engines and I have no practical expertise in engine mods.
There was a company called Jakan Honda who would do work like this. But sadly I think they have ceased trading but the expertise is out there.

Lowering the VTEC kick in point is certainly possible and would be a bit like dropping a fast road cam in. I seem to recall this was achived with a piggy back type device rather than a remap.

The head work I suggested should give a power gain in the mid range region but as you say it is a bit extreme but would make the car overall seem more willing to go.

It is nice to know that Honda over engineer their engines. I guess this is why a lot of people have got away with adding superchargers and turbos to them.

If you ever get the clutch done then look at a lighter flywheel as well.
Thanks Wayne, I'll have to keep Googling for Honda VTEC remapping.

If I want to start doing the porting etc, where do I look for the inlet and exhaust manifolds etc ?
CNC have a pretty good reputation. Just get some angles cut around the valves in particular, it really does help make the engine more efficient.
formulas , speeds in gears etc etc are all very well but the simple fact is your engine wont rev like an R unless you tune it like an R

You are right that just increasing the revs on the same engine wont decrease torque
but if it wont rev higher the formula cant be applied.

To raise the rev limit you will need to change the engine spec and this will change the characteristics and that WILL change the torque.

Without wishing to be confrontational you say you know nothing about tuning engines but when someone does offer help ( and I do have a V tec civic ) you seem to suddenly become an expert and dont want to accept the advice which was supposed to be helpful.

Waynes info by the way pretty much agrees with what I am saying.

BTW honda diodnt just cut the revs on the accord for a longer life - they cut it by detuning the motor which of course does make it more reliable because there is less stress
I was not sure what advice you were trying to give :eek:

Your last reply is the sort of direct answer that I wanted. If you have a Civic then your advice is what I want.

I have several very old British carb cars, and what stops them revving is the breathing, which also represents a steep decline in torque. When you say "increasing the revs on the same engine wont decrease torque but if it wont rev higher the formula cant be applied" does not make sense, because if the torque wont decrease then the engine will rev higher. With or without a formula, if the torque does not decrease then the engine will rev higher (if the rev limit is removed) which means that the engine will deliver more power in lower gears.

However you then say "honda didnt just cut the revs on the accord for a longer life - they cut it by detuning the motor which of course does make it more reliable because there is less stress", which suggests that if I get the rev limit removed, it will be pointless because the breathing will make the torque drop off rapidly as it goes over its present electronic limit. This point of your does make sense.

I'm sorry if I appeared to "suddenly become an expert" but ambiguity confuses me. With the electronic limit removed then either
- the engine will rev higher without loss of torque
- at higher revs the engine will no longer breath and so there will be a loss of compression on the pistons (loss of torque) which will be dangerous for the pistons

On my engine it seems strange that the high lift cams only come in at 6000 and then the engine hits the end stop at 7200, it just feels as though it would go on to 8000 without loss of torque. But will it ???

That is what I want to know, without ambiguity, and also where I can go to get the rev limit removed if this is safe to do ?

Alternatively, where can I go to get the engine remapped so that the high lift cams come in earlier, hence more torque (power) earlier in the rev range ?

Finally, if I decide to get serious on this engine and go to improve its breathing, where to buy parts and the sorts of prices ?
Maybe my explanation wasnt good so I will try to explain it a different way (bear with me )
First of all lets put all the formulas and engine specs to one side just for a moment.

All engines have a natural rev limit which varies depending on the specifications the engine is built to .
.On japanese car engines is usually to do with the head/cams/valve .But it could be a restrictive exhaust or fuel system or even piston speed .

On higher revving engines power certainly does not neccessarily increase proportionally with revs but the likelyhood of engine damage does. So an artificial rev limiter is sometimes fitted to stop this damage occuring.
The more tuned the engine is the more likely it is to have such a limiter

For example I also have a highly tuned nissan that will rev to over 9000rpm on high boost but I dont want it to because 8300 gives sufficient power and the torque and power drops off so dramatically after about 8000
The rev limit is set to 8300 by the ecu which is aftermarket and adjustable. No matter what I do it cannott rev over 8300 because the spark is cut.
The important bit (thats relevant to our discussion ) is that this gives the appearance off a missfire which is very easy to feel.

It doesnt make sense for car manufacturers (especially japaese car builders) to put such a rev limiter on for the sheer hell of it.
Instead they design the engine to be viable in stock form up to its natural rev limit
A prime example of this is my civic . It revs it happily enough but stops at about 7300 .
It stops here because the head set up - valves, cams , porting etc simply do not flow well enough to allow higher revs and not because of an "artificial" rev limiter .
This give a smooth engine up to the 7300 without a missfire suggesting that the engine desin itself is the limiting factor as far as rpm is concerned.

My point about formulas was that if an engine is restricting itself to say 7300 by way of head design then until the flow is improved it wont rev higher full stop .
If it wont rev higher a mathematical equation might be correct but wont make any difference to the engines actual rev limit.

As far as the formula goes it cant calculate anything without either the bhp or torque figure

You can measure bhp on a rolling road and then calculate torque using the formula but not the other way round.

There is another important factor - you only get more power when increasing the revs if the engine can "process" the neccessary extra fuel with roughly the same efficiency

On my civic (and I think your accord) the engine cant but on the Type R it can

That is the difference and that is what you need to address to get more power.

I cant help with where you sould go because I ahve never wanted to tune my civic but any well known honda tuner will be able to tell you easily enough . A visit to the honda section or the civic/accord forum would find the answers.
Thanks for taking the time to say all that, very very interesting.

I certainly didn't want to get off on the wrong foot, unfortunately I did, but the formula was just a way of trying to explain what I meant.

But I get what you meant now. I now believe that if I had the electronic limit removed without changing the engine breathing, it would self destruct, not on the first time but at some time other unpredicatable time. Or bugger the cat quite quickly.

I've called a few ECU remappers and they all say that it is possible to get the high-lift coming in sooner and remove the rev limiter if I wanted, but of course they would say that wouldn't they !!
I dunno about vtec but I do know that forcing variable intake systems to come in earlier can have adverse effects on torque - lower down the rev range a longer intake path helps to increase torque, further up a shorter one helps power - making the intake shorter lower down the rev range you can lose torque.

I think I'd want to do a lot more research before messing with a key part of the engine.

Or alternatively, stick an S2000 engine in it. Or more alternatively, supercharge it, I know people have done this to S2000 engines.
You might have a good point there about the lower revs, that is why I'm really looking for a tuner/remapper who knows about VTEC.

The angle of the inlet cams can be varied in the engine map, I took the valve/rocker cover off the engine today and took some pics.

The head can be seen in wiipedia (I went to wiki after Yugguy suggested it): CLICK HERE

This is the engine in my car:

This picture shows the inlet cam, it has a system where the phase of the inlet cam cn be varied:

Finally, not very clear, at the other end is the mechanism for engaging the high lift:

** How easy is it to put in a super-charger, where does it take the drive from ** ??
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hey and welcome.

the reason you may be struggling to find a remapper for the petrol engines is im pretty sure the K series cant be remapped it requires an aftermarket ECU

the type r engine is also quite different to the standard 2ltr engine hense why they rev differently .

the honda engines seem to like being supercharged as for where the drive is taken from ether custom build into the auxulary belt or by removing another item and replacing it with the pulley from the charger - air con for example
i would advise only low boost and you should be fine, honda make strong engines.

if you want high boost then you will need to look at stonger rods etc

and you may also need to look towards a new ECU for a proper map
I like the sound of this, this is the sort of mod I would be prepared to start doing, any ideas where I can get a suitable "kit" ?
"scrapyard" to me is a place where scrapped cars are found (sorry if I sound pedantic), if that's what you mean then what sort of car ?
Do a search for supercharger and our member claymore, he's fitted a couple to his Volvos in the past. At low boost it is relatively straighforward. (You obviously need to up the fuel and alter the timing slightly.)
You'll need an Eaton m62 off a mercedes (Ebay), then it's a case of mounting it in place of the aircon pump (if your car has aircon) you will need to move the throttle body to before the SC then its just a case of plumbing, you will also need an intercooler and probably a piggyback ecu, (I generally use dastek).
Sounds good, I just checked on ebay, not any M62, but there are M45's (some say BMW Mini), but I guess M45 is OK ?

Not sure why I need intercooler if it's going to run at low boost, also thought intercoolders mainly needed for turbochargers ?

Piggyback ECU ... I presume it will do a straight-through for the inlet cam control from the main ECU ?

Yes it does have aircon.
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m45 will be to small for a 2.4, and you will deffinately need some sory of charge cooling, superchargers produce huge amounts of heat,
does it matter that the throttle is ECU controlled "fly-by-wire" ?

I'll have to wait for an M62 to come up on ebay (or go to scrapyard as suggested by pgarner before)
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OK to that

I guess some of the installed ECU outputs will have to bypass the dastek e.g. throttle control and control of inlet cam ?
the dastek cuts into the ecu loom and modifies the signal from the Maf, crank sensor, lambda etc, to the ECU
Crikey I just looked at their website and found this feature list:

Variable valve timing adjustment
Rev limit adjustment
Boost limit & level adjustment
Dual maps for use with different fuel grades & types
Water Injection
Nitrous oxide progressive injection
Bigger/supplementary injector handling
Variable induction control
Launch control for turbo vehicles
Full throttle gear changes
Road speed limiter removal
Speedo conversion for imports
Shift light
Idle speed stabilisation

I'll have to get more info from them
I used the launch controle and nitrous controle on my old Fiat :)
and will probably use the same on the Volvo.

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