4g69 cylinder head upgrade options

Radical_Ralliart

Radical_Ralliart

Member
Haven’t found a thread talking about cylinder heads so thought i’d start one. (This would be about keeping the engine N/A)

I’m considering buying either a whole 4g69 engine or just the cylinder head at some point. Im wondering if theres decent power to be gained from just upgrading the head.

Is it worth upgrading the camshaft with stock bottom end? (Thought about stage 1 n/a rpw cam but i’d like some input on tuning specs between different stage cams)

Is there good benefits from port and polishing?

at what point would upgrading the valve springs be necessary?

would be beneficial to get the head surfaced decked, and is it safe to lap the valve seats using a grinding compound? (Permatex compound for example)

I’d like to get as much info and insight into these engines as i can. i’ve never torn apart an engine or modified one, but i really want to try my hand at it.
 
There is always the opportunity to gain HP and torque by porting and polishing your cylinder head ports. There are a LOT of sub topics that nobody really agrees on but as a general rule you want to slightly widen/open up the ports, ensure they are all even and the same, remove flashings from castings and aim to knife edge or smooth out port dividers. Uneven-ness is the enemy above grinding out material from your head. Polishing finishing is the big unknown - some say mirror finish, some say golf ball dimples.. You can spend days reading or researching this stuff, the only real way to know is to try it out!

Personally, I like the JafroMobile approach, as the roof of the port is the long radius of the runner, he suggests polishing the roof and upper side walls to a finer finish that the floor of the port. In this way, all of the air should flow evenly through the port, with the higher velocity air at the longer radius. Its just one idea, don’t take it as gospel.

Cam shafts - again, nearly always gains to be made, but you will enter the realm of trade offs. A cam focused on higher rpm HP will often sacrifice low down torque. Even some cases sacrifice mid range for that last extra HP at 7500rpm. Just have to make your choices. If you circuit race above 5000rpm consistently, go for the big boi cam. If you street drive, mostly using that 2500-5500rpm range, focus on that!

Stage one or two on a stock crank is fine.

You need upgraded springs when the cam becomes too aggressive for the factory springs to retain the valve on the end of the lift event. This gets worse as RPMs increase. So a steeper ramp angle on a cam can have an effect, rather than necessarily total lift.

I would personally put off upgrading springs unless you HAVE to. It adds friction to the valvetrain across the whole rpm range, so it could cost you a few HP and fuel economy down low for the gains up high.

Decking the head within standard tolerance is the way things should be done bare minimum for head removal and replacement. If you deck beyond the standard clearance you’ll be increasing the compression ratio - don’t do this without being able to tune the motor!

Valve lapping is another standard technique for setting valve seats. Do this after having your valve seats cuts on a CNC mill. There’s no reason to get anything less than a 3 angle cut theses days. You won’t net mega HP here but it will help accross the WHOLE rpm range no matter what, by having this setup correctly.
 
plus 1 to Sdate. porting is a black art.

and tbh it might be over kill and not even needed, the porting, the cam, the bottom end, the tune all need to work together to get the best out of each other component. no point having a head that flows like a formua1 engine attached the bottom end of a tractor motor. the bottom end will be the limit. no point building a strong bottom end if the oil pump and head will rattle themselves to peices at high rpms. it's all a balancing act.


old forum info is sill somewhat relevent, shame the pictures are so hard to find (thanks photobucket you f**ks) but the russians and the yanks had the 4g69 in their eclipses and galants...and these cars are 15ish years old so theres always at least one other person in the world who's done something on them.

Stayer. Porting the cylinder head. Stage 4.

Hi friends! In this topic I want to talk about the work with the cylinder head. Earlier, in its various topics, I mentioned that doing a big project 4G69 (N/A). The planned capacity of at least 100 HP per liter volume. I think it will be more. When I assemble the entire engine, I will write a...
www.thegalantcenter.org www.thegalantcenter.org

Stayer. Porting the cylinder head. Stage 4. - EvolutionM - Mitsubishi Lancer and Lancer Evolution Community

04-06 Ralliart Engine/Drivetrain - Stayer. Porting the cylinder head. Stage 4. - Hi friends! In this topic I want to talk about the work with the cylinder head. Earlier, in its various topics, I mentioned that doing a big project 4G69 (N/A). The planned capacity of at least 100 HP per liter...
www.evolutionm.net


not related but interesting

4G69 Tear Down Detail - EvolutionM - Mitsubishi Lancer and Lancer Evolution Community

04-06 Ralliart Engine/Drivetrain - 4G69 Tear Down Detail - So I mentioned possibly making this thread a while back and a few people seemed interested in it. Just up front this wont be an entire tear down. But it will show most of the engine and I will be trying to collect as mush information...
www.evolutionm.net


ohh and another point: cause its a mivec engine, you have two cam profiles to look into. low and high lift: again, both these profiles need to work harmoniously together
 
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Thanks for all the info i really appreciate it, in your guys experience what cam spec would suitable for daily/street driving but still gives me better power?
 
Radical_Ralliart said:
Thanks for all the info i really appreciate it, in your guys experience what cam spec would suitable for daily/street driving but still gives me better power?
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have you read this? https://auslancer.com/index.php?threads/ch-2-4l-tuning.11515/

if you were dead set on a cam; it wouldnt need to be too much more aggressive to make more power. mivec high cam profile is huge anyway. you could probably do a more aggressive low cam if you wanted some lump to the idle, but its dollars for noise.
 
unclepaulie said:
have you read this? https://auslancer.com/index.php?threads/ch-2-4l-tuning.11515/

if you were dead set on a cam; it wouldnt need to be too much more aggressive to make more power. mivec high cam profile is huge anyway. you could probably do a more aggressive low cam if you wanted some lump to the idle, but its dollars for noise.
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I’ll give that a read soon, ideally i’d like a cam to give me a bit more power over most of the rpm range, dont want to sacrifice too much low-mid power
 
Most immediate would be outlander decatted headers, and a free flowing exhaust/high flow mid cat if possible. That along with a decent intake system that actually pulls cold air, will give you the basis to go and get your first tune. There is good power to be gained just from doing this and tuning, as the 69 does have a decent amount of emissions restrictions that can be wiped, allowing for easier breathing. I will likely be doing this for my build in the mean time before the cam.

Aside from these simple upgrades, everything else becomes an invasive process as mentioned above. Cams, springs, headwork yada yada.
 
Cleanmin said:
Most immediate would be outlander decatted headers, and a free flowing exhaust/high flow mid cat if possible. That along with a decent intake system that actually pulls cold air, will give you the basis to go and get your first tune. There is good power to be gained just from doing this and tuning, as the 69 does have a decent amount of emissions restrictions that can be wiped, allowing for easier breathing. I will likely be doing this for my build in the mean time before the cam.

Aside from these simple upgrades, everything else becomes an invasive process as mentioned above. Cams, springs, headwork yada yada.
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Does it matter what year of 4g69 outlander it is? I’ve seen this mod before but i’m afraid wreckers would charge me like $300 for them.

At the moment i have a 2.25” cat-back, but stock cat and headers. If i decatted some outlander headers and got a 2.25” high flow cat, would i have to get the rear o2 sensor deleted or changed on the ecu?
 
Stock cat and headers are the biggest killers. Yes you can go and spend money on headers but just see what the availability and going rate is for outlander ones as they are decently tuned and decatted, you don't need to decat those. The rear 02 sensor may have to be looked at depending on how high flowed your second cat will be. I have heard of people spacing the rear 02 sensor out so that it tricks the ECU. But ultimately a tune is the best to get the most out of the situation regardless
 
Cleanmin said:
Stock cat and headers are the biggest killers. Yes you can go and spend money on headers but just see what the availability and going rate is for outlander ones as they are decently tuned and decatted, you don't need to decat those. The rear 02 sensor may have to be looked at depending on how high flowed your second cat will be. I have heard of people spacing the rear 02 sensor out so that it tricks the ECU. But ultimately a tune is the best to get the most out of the situation regardless
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I hit up off the clock motorsports, and alvin said that he could delete the rear o2 sensor for me, at the moment i think what i’ll do is grab those outlander headers, get a magnaflow cat fitted and throw in the tuned ecu.

Would i have any problem by following this?
 
The stock cam specs are as follows:
Opens Closes Duration Lift Center
Intake Lo 10 BTDC 42 ABDC 232 4.094 106
Intake Mid 12 BTDC 44 ABDC 236 9.344 106
Intake Hi 24 BTDC 68 ABDC 272 10.3854 112
Exhaust 58 BBDC 18 ATDC 256 9.9266 110

So we have a single exhaust lobe that is something like a typical stage 1 cam already.
The intake has 3 lobes:
Intake Lo operates on 1 valve and Intake Mid operates on the other valve.
At around 3500rpm, the Intake Hi lobe overrides both Lo and Mid lobes so both intake valves are operated by the Intake Hi lobe. Note the Hi Lobe is damned near a stage 2 cam spec.
The reason for the crazy difference in the low speed lobes is to generate a swirling effect while filling the cylinders.... hence the term "cyclone engine". This is a bit of misguided engineering harping back to 2 valve heads and carbies where this swirling was useful to mix the fuel better but a 4V head inherently has a tumble filling action that is now universally embraced as the superior mixing and flowing technique.
So to answer a few questions:
Yes the head can be shaved to a maximum of 23 thou - this is the point at which the valve seat starts to get shaved. I did this to increase the stock 9.5:1 CR to around 9.8:1. Pic shows how close the intake valve seat is to the shaved surface.
20220330_105919.jpg

Yes there is a benefit to porting the cylinder head. As part of the "cyclonic action", the ports are somewhat obscured to one half of the valves. These ports can be improved largely by reshaping the port divider in favor of the obscured side - there is zero point in trying to preserve the failed cyclonic action. The exhaust side is more the problem child...
Pic shows intake ports after a mild narrowing of divider.
20220330_105806.jpg
and here the exhaust side showing how obscured one valve is and this is after reshaping the divider to open it up a bit!
20220330_105648.jpg

This is done on an Outlander CU5W so it already has a perfectly good 4-2-1 exhaust manifold so no need to drop brand names here.
Next part of the puzzle was to flash tune it. Biggest gains were in ign timing and fuel correction maps. A pretty easy tune to do without the complexity of VVT. It is apparent that the intake low cam profile is a very unfortunate choice with its miserable lift and also the hi cam profile is actually a bit too aggressive (for the low compression ratio). The ideal situation would be to run this engine at 10.5:1 - the stock low compression is the biggest drawback of this engine! I did a bit of research into finding compatible pistons from other cars i.e. Honda K24 etc. but nothing close enough to do the job :angry: Possibly something out of the Chinese clone stable might work - they still use a revised 4G69 engine in many vehicles.
Is it worth throwing in some aftermarket forged pistons? For me the answer is no since I only wanted to get a bit more power and economy out of the old girl while I had the opportunity with the head off for a bit of a preventative recondition.
So there you go.... answers from someone who has actually done this for a change....
 
A potential source of cheap hi compression pistons might come from Chinese made (by S.A..M.E) 4K12 engines that are essentially a 4G69 block with a new head similar to the Mitsi 4J1x engines. The CR is 10.5:1 with the new head but is probably going to be the same if used with the original 4G69 head or close to it. These 4K12 engines are used in various China brands. There is also a 4K22 engine along the same lines but RWD only. Check out the latest GWM utes and you might find they use these engines. Just need to find a pic of the pistons and a supplier......
 
Here are the figures I used to calculate CR:
Stock CR 9.5
Bore 87mm
Stroke 100mm
Dish height -1.9mm

Head chamber volume 55cc --> 52cc after 23thou shave
Dish volume 7.7cc
Gasket thickness 0.75mm

594cc per cyl
4.56cc gasket
69.855cc chamber + dish + gasket + crevis
=9.5:1 CR
=9.885:1 CR with maximum shave

And here are the piston specs if hunting for alternatives....
Pistons.jpg
 
So after doing some research I’m considering getting rpw to install their stage 1 camshaft, i’ll be buying the AEM long ram intake fairly soon so that’ll help out with air a little bit, still haven’t decided on what exhaust headers i want.

So the stage 1 cam profile seems to be pretty good, only adds a little bit of lift but the duration looks to be better
(these cam specs are from RPW themselves)

USDM ralliart 4g69 cam: (the same as aus 4g69 as far as i know)

Adv duration intake low: 165
Adv duration intake high: 202
Adv duration exhaust: 182

Valve lift intake low: 0.210”
Valve lift intake high: 0.245”
Valve lift exhaust: 0.230”

Rocker ratio: 1.5

RPW stage 1 n/a cam:

Adv duration intake low: 248
Adv duration intake high: 267.5
Adv duration exhaust: 247

Valve lift intake low: 0.327”
Valve lift intake high: 0.347”
Valve lift exhaust: 0.327”

Rocker ratio: 1.5

Not really sure what kind of power gain i could get from this cam but the guys at RPW have said with a full exhaust, cam, intake and tune it could net me 40-45kw extra. Not sure if they’re capping on that
 
A word of advice.... putting a longer duration cam in an engine that has an already pathetically low compression ratio will reduce the dynamic compression even further making the wishful expected gains disappointing but on the bonus side, you can use the engine to dispose of stale fuel out of the lawnmower can or outboard tanks.
A stage 1 cam needs a starting point of 10.5:1 compression ratio, preferably 10.7:1~11:1 and even then it will still run happily on our crap 91 octane fuel. On stock cam which is not too bad on the high lobes, the engine has plenty of get up and go. It is only on the low lobes that it is a bit wanting but if you are going to thrash it, you will be spending all the time on high lobes. Re-read post#13 to get the actual stock cam specs.
 
Just on the thought of high comp 4g6x…

AB did a turbo 4g69 with DOHC from a 63 or 64 from memory and that had crazy comp, particularly for the boost he was trying to run.

I looked at this route previously for NA and found that the specs for DOHC cams were really only suitable for turbo applications but maybe there are more options now than 5 years ago. I think this path would be equally as costly as forged/custom bottom end setup.

You would also loose MIVEC unless you wrangled an evo9 head.
 
Important to know the difference between 4G64 and 4G69 as far as pistons go - particularly compression height. DOHC head off a donor Hyundai Sonata (that also had a 4G64 engine in it in the older years but as a DOHC variant) is probably a cheaper option than a Mitsi 4G63 head. Did look at the DOHC option for mine but not a lot of gain for a huge effort (and cost). Don't underestimate the 4G69 head as a good thing as well as the intake manifold that is way better flowing than a CJ Lancer plastic version that runs out of puff at 6300rpm. The only thing really wrong with the 4G69 is the stupidly low lift on one of the intake valves. If that was the same as the other valve, it would perk up nicely at low rpm. I see no need to go a bigger cam as that really only pushes the power band into a range that only a fool would run a 100mm stroke engine at... think piston speed. Mitsi got it bang on the money with the rev limit to not exceed a piston speed of 23m/s.
 
Thanks for the tips jajk,

I’d like to be able to buy the 10.5:1 comp ratio pistons from rpw but i keep hearing mixed reviews on their parts and their work, I don’t want to spend a few grand on a 4g69 if it’s just going to fail.

Is there a reliable piston that will increase the comp ratio that works for the 4g69 out there?
 
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