Thoughts on an NA build.

[cheekychimp]

After driving the Galant Gti in the UK I was pretty impressed with the power (albeit a pre-facelift 145 hp model), but wanted to see what I could do to improve things (a) on a budget and (b) with relatively little work (at least on my part!).

To be honest having delved into this there doesn't seem to be a great deal involved in going from the pre-facelift GTi 145 hp up to the AMG 167 hp (or higher). Post facelift GTi models made 160 hp on what seems to be nothing more than higher compression and possibly ECU tweaks whilst the AMG made 167 hp (just a few horses more) with an uprated valve train and a different intake manifold (and possibly better headers). Camshafts actually appear to be identical in terms of lift and duration between all three models.

Pre-facelift compression was 9.8:1 whilst the AMG and later model Gti were raised to 10.4:1.

So here is my question. There are two ways I have been told I can increase compression. The first and obvious one is to buy and install brand new higher compression pistons. I'm not sure how much this would cost in parts but it seems like quite a lot of labour and if I had to get it done at a shop in the UK very pricey.

The second and less orthodox one is to find a second hand/junkyard 93-95 Hyundai Elantra head and get it milled down to bump up the compression. Any thoughts on this? I'm just thinking if I could find a head and get the work done, I might be able to just do a head swap myself without having to go to a shop.

 

[strokin4dr]

Neither of these options seem to be worth the hassle for a few hp more.
Throw a stock turbo setup on it and have a fun little fwd DD.

 

The USDM 2.0L heads are 4cc larger than the elantra head. When starting with 9.8 CR, decreasing chamber volume by 4cc would net a pretty decent bump in CR. Would probably put you a tad higher than 10.4, I'm thinking probably 10.6. Should work nicely considering everything is transferable between the two castings. You would even be able to use the evo beehive springs if you wanted.

 

[IncorpoRatedX]

Brian (a2vr4) is building a 4g64 high compression automatic galant gsx.

I think it's a great idea for a daily driver.

 

[cheekychimp]

Yeah, I think I read that the Elantra head on the 4G64 nets a CR of 11.0:1 or more right? It seems like a really nice setup which is why I am anxious to try it on the GTi. I know I could boost it but that seems like far more work and it requires a whole load of parts that I just don't have in the UK.

On a separate note, what is Brian doing about tuning Josh? I live really close to the Aquamist headquarters in the UK and I was wondering if I could get away with just using a simple WI system to counteract any added compression without messing with the fuel/timing maps but is that even going to be necessary with a bump of less than one compression point in my case?

 

[DR1665]

Above 10.5:1CR, I'm going to hope you've got access to quality fuel there - 93 RON or better. I ran 10.5:1CR in my Talon on a tweaked AFX/R ECU on 91RON (best we get here in Arizona). Below 3000rpm, when ambient temps were above 100°F, would result in knock - in any gear. I had a MegaSquirt in-hand and was going to set it up to control water injection, but then realized I had built an all-motor drag car and wanted to rally. Never installed the MS.

If the head swap is a direct bolt-on affair, I'd give it a shot, but be damn sure what your final CR will be with that setup. Find specifications and calculations. No offense to those who have suggested said Elantra head might net you 10.5-10.6 or 11.0:1CR or anything, but do the math. You're considering something relatively rare in a community which tends to the sloppy, low-compression/high-boost end of the spectrum. Increasing CR brings you closer to the edge. There's nothing wrong with daily driving right there (I did for two years), but if you're going to do this, you want to KNOW what you're doing.

Pop a motor and say, "Damn. I double-checked my math and that should have worked," you'll get the respect.
Pop a motor and say, "Damn, so-and-so on such-and-such forum said that should have worked," you'll get no sympathy.

FWIW, my preferences would be, in order:
1. direct bolt-on head with reduced volume chambers (only if it's the same form factor - must be same height)
2. replacement pistons
3. shaved head (Actually, I'd pass on this. It's half-assed.)

 

[bazeng]

Go a 2.6L high comp N/A motor!
That would be very interesting!

I've driven my 2.3L stroker in N/A mode with about 8.2 c/r and it had ALOT of torque!
Mind you it was with a VR4 RS box so that could have helped...

 

[joggle]

Some information can be found here:
click

 

[Rausch]

Quoting DR1665:
Above 10.5:1CR, I'm going to hope you've got access to quality fuel there - 93 RON or better. I ran 10.5:1CR in my Talon on a tweaked AFX/R ECU on 91RON (best we get here in Arizona).

Don't you mean AKI? 91 RON would be the same as 87 AKI (pump labeled 87 Octane) "regular" here. 98 RON is about the same as our 93 AKI (or 94 Shell) "super" stuff. If you get 91 AKI in AZ, that's more along the lines of 95 RON when converted.

 

[RedTwo]

If only you were crazy enough to jam some MIVEC onto it... /ubbthreads/images/graemlins/idea.gif

 

[AnotherNewb]

Couple of thoughts on the subject since I have considered a NA build. You can swap a 4g61 head onto a 4g63 and also get a higher compression ratio. What I was thinking about doing was taking a 2.4l, 4g64, and swapping on a 2l, 4g63 head and that would effectively net you 11:1 compression on stock pistons. Drop Jesse_w a pm and see if he can get you the email address to his neighbor that races 1g's on the dirt track. That guy has done some interesting albeit illegal for his class mods on his NA car to get him some interesting power out of a stock appearing motor.

 

[fuel]

if you wanted to remain 2.0L, and don't mind switching to 7-bolt (ie better for revs and mid-range torque), the 93-96 RVR Sports Gear has the highest factory compression ratio 4G63 at 10.5:1 (slightly more than the AMG engine) and puts out 160hp. I had a '93 RVR Sports Gear and for a heavy pig the N/A engine moved it along just fine - there were many times I was able to get the back to step out around wet roundabouts - it was such an odd handling car. Being a 7-bolt it has the smaller port head - using AMG cams and higher flow intake manifold along with aftermarket exhaust headers would really make it wake up.

 

[cheekychimp]

Thanks for all the info guys, there is a lot to be thinking about here and a whole load of options that are clearly available for this car in the future, but the whole point of this thread was to do this with the least amount of work. I have the greatest respect for you guys and what you are capable of doing yourselves. I do want to learn to do more on these cars myself, but an entire engine swap is not something I feel confident to tackle right now, never mind all the other issues and headaches that that would bring, what with licensing, insurance, locating 4G64 parts etc. It is just too much when I only have a few weeks with the car.

What Driggsy has said makes the most sense here and actually covers my biggest concern ... tuning. Since post facelift GTis had the higher 10.4:1 CR it suggests that they should run just fine on UK pump fuel. MY JDM Civic Type R runs fine over here on the lowest quality pump and I believe that is an 11.5 CR!! The issue here is that the ECUs have been mapped to run on pump. I'd be running an ECU mapped for 9.8:1 which could well have more aggressive timing that will need to be pulled. I'm pretty sure timing is as important as fuel in this equation.

The real question is if I cannot tune timing or get a later model ECU that actually works with this car, can I eradicate knock with water injection alone? If I can, I have access to all of Aquamist Headquarter's expertise about 15 mins drive from my house in the UK.

Edit: Regarding the 4G61 head. I notice in that link that was supplied (thank you for posting that) that the 1.6 litre head has the same 43 cc combustion chamber but "smaller ports." Do those heads still have 1G sized intake manifold ports or 2G sized ones?

 

[DR1665]

@Raush - My bad. Yeah. AKI or whatever. The metric system all over again. /ubbthreads/images/graemlins/tongue.gif

@Chimpo - I suspect you might want to consider DSMap/Jackal for tuning. Go speed density, use a spare channel to control the Cyclone, and trigger water injection when IAT > 40*C and injector DC > 80% or WBO2 starts looking lean or something.

Smaller runners are better for an NA runabout. Remember the intake conversation? Torque is a function of charge velocity, which is a function of port diameter. Larger ports (ie; turbo) would shift powerband upward.

For the most economical stock, I'd go big 16G or larger w/ the turbo head. No boost before 3500-4000rpm, so you could granny shift it around town, but shovel a bit when you needed it.

Sorry for typos. On Blackberry.

 

[fuel]

my understanding is that the 4G61 (and 4G67) have smaller ports similar to a 2G rather than a 1G, but I'm not 100% sure if they are the exact size as a 2G port - perhaps just a little bit bigger than a 2G port.

 

[cheekychimp]

Fuel, there seems to be some controversy over this. Well actually no, pictures speak louder than words so unless someone photoshopped their images it seems that there were actually some 4G61t heads in some markets that came with the larger 1G intake runner ports. I'm just not sure if this means the ports change in size after the intake.

So it looks from this then that I could either go 2G manifold with a smaller intake port head or throw a Cyclone on a larger port one. At least that is a few more options. Now I just need to locate a head in the UK. The cost of shipping a head to the UK from the States could make this mod far from a budget one.

 

[89Mirageman]

From what I have gathered the true Mitsubishi 1.6L head does have the smaller intake ports but every Hyundai 1.6L head that I've seen has the same size ports as a 1g dsm. Also I'm not sure if you'd be interested but I have a pair of cams from a rare 94 Galant GS (manual transmission) which had the 2.4L DOHC engine. A buddy of mine found some info that said these were high lift cams and would be great for a na build. I can ask him to forward me that info again. Then again they may be the same cams you already have since its not a US built na engine that you're dealing with.

 

This may help.


clicky

 

[curtis]

Paul remember if you get a head from a junkyard its going to need to be milled and this can throw the CR up as well. Pay attention to the crush thickness of the new head gasket as well. All of this can be counteracted with some combustion chamber clean up but you'll need a graduated cylinder or pipette to check each port when done. After the age of non prescription medications both are fairly hard to find outside a classroom might have to go to the property locker at work for one.

First figure the cc volume of the head gasket crushed. Probably going to be small 1 or 2 cc's then best way to do it is get some springs you can install by hand on the valves. Just enough pressure to seal then a thick piece of lexan with a small hole drilled into it and spread on some vaseline on the head surface, press the lexan down tight and start filling them up. You and a dremal tool after a few hours could have a head thats balanced on all 4 ports.

 

[cheekychimp]

Quoting 89Mirageman:
From what I have gathered the true Mitsubishi 1.6L head does have the smaller intake ports but every Hyundai 1.6L head that I've seen has the same size ports as a 1g dsm. Also I'm not sure if you'd be interested but I have a pair of cams from a rare 94 Galant GS (manual transmission) which had the 2.4L DOHC engine. A buddy of mine found some info that said these were high lift cams and would be great for a na build. I can ask him to forward me that info again. Then again they may be the same cams you already have since its not a US built na engine that you're dealing with.



That makes a lot of sense and could well be the case to be honest. As for those cams, I don't think they will be beneficial to this particular build because going from the information given on all the various OEM cam profiles given in the current EVO 8 cams thread in the technical section it appears that the GTi already has cams that are even more aggressive than those rather rare 94 Galant GS ones. That said is there any reason why NA cams can't be used in a turbo build seeing as those cams are more aggressive than the stock turbo ones? I know Aaron mentioned that on stock cam gears they may be set up with more overlap for an NA application but couldn't that be dialed out with adjustable cam gears?