4g61t.org

I start to modify my engine, and I want to know if I change the pistons ( x1 pistons ) 10.5:1 CR, it will be a reasonable upgrade? is worth it?

how much will be the gains?

i already search , i only want confirmation about this, i dont want to spend money on this.

beside that I want to balance the camshaft.


if I install those pistons and I get my head a little shorter ( what is the exact word? ) how much would be the max to do it and get a 11:1 or 11.5:1 CR? without valves would bend with the cylinder?

thanks.

_________________
Stock Sucks...!!
Mods List:

Custom cold air intake
Iridium Sparks
NGK sparks plugs wires
2" exhaust and moffler
ACCEL Coil
240cc inyectors
52mm TB
K&N filter
Elantra BRAKES ( upgrade )
195/50 R15
2.5" lowering springs
Ate. brake Fluid

11.5 to 1? Would this be a street car? You're gonna have to use OCTANE BOOST or RACE FUEL dude!

Anyways, I'm sorry. I can't offer you anything as to confirmation on this mod. But I'm HIGHLY INTERESTED as well.

I've read in this and other forums regarding this piston swap to increase compression to 10.5 to 1 in our 4g15's, but have yet to see a thread in ANY forum of anyone who did it.

Has anybody done this or increased their compression ratio via other methods? If so, let's hear the pros and cons you've encountered, your set-up, power output, etc. We'd like to know.
G.

I really want to know too, i want to get the higher CR as long I dont have to use octane booster. i want my car for street.

what CR could be the highest?

I need confirmation about this, i dont want to explore with this.

^^like he said anyone has done this mod? any other method?

_________________
Stock Sucks...!!
Mods List:

Custom cold air intake
Iridium Sparks
NGK sparks plugs wires
2" exhaust and moffler
ACCEL Coil
240cc inyectors
52mm TB
K&N filter
Elantra BRAKES ( upgrade )
195/50 R15
2.5" lowering springs
Ate. brake Fluid

I've seen one 1.3 L Citroen AX Sport (more info about AX here) over here with 13:1 compression, and it runs finee on regular 98 octane pump gas... So, i have a question: where's the problem with Mitsus? I've never seen Mitsu with that high compression...

Oh, and sorry, i'm offtopic, but i really don't know a thing about X1 pistons...

_________________
2000. Hyundai Sonata EF 2.0 (Hyundai version of 4G63 and F5M22)
1991. Mitsubishi Lancer C62 1.5 (4G15, F5M21)

Well you know how all those "rumours" got started dont you?

I used to have an X1 Excel 4G15 bottom end (carby motor) with a X2 Excel 8-valve 4G15 head. If you just slap those 2 together you get a CR of ~10.5:1 which runs fine on premium fuel even with advanced ignition timing.

There are no problems with valve interference or anything else, just use stock cam timing, stock everything.

The 4G15 bottom end I built myself with balanced internals and the 8v head was professionally ported. Otherwise it was stock. It made pretty good power all the way to 6800rpm rev cut, especially in the mid-range (stock cam). Unfortunately that motor was let down by the stock X1 Excel KM-164 gearbox with its 3.4:1 final drive which was destroyed by the time it all came out ready for the 4G61T.

so... just the pistons wont give me that CR ( 10.5:1 ) i will need the excel head, right?

sorry if I misunderstood.


one more question, wich be the best 2" or 2 1/4" for exhuast pipe?

i saw that the best is the 2" but some of you guys has the 2 1/4"

_________________
Stock Sucks...!!
Mods List:

Custom cold air intake
Iridium Sparks
NGK sparks plugs wires
2" exhaust and moffler
ACCEL Coil
240cc inyectors
52mm TB
K&N filter
Elantra BRAKES ( upgrade )
195/50 R15
2.5" lowering springs
Ate. brake Fluid

If I can run pump gas with a turbo then you can do it with upped compression.











If you have any questions about this set just ask.

_________________
2012 Explorer Limited
1989 Colt GT clone 4G63t auto
1992 Talon TSi
1990 Talon TSi
1995 Crown Vic
1993 Ford F-250 BBF
1987 Chevy Sprint Turbo

I guess that setup would work - pretty stealth at the least. I notice the inlet manifold brace has been removed to make room. How is the turbo being held up in that postion?

No you dont need an Excel head since the X2 Excel head is the same as all the Mitsubishi 8v EFI heads.

It still had the exhaust mount on the front of the block. Yes, it was a very tight squeeeeeez.

_________________
2012 Explorer Limited
1989 Colt GT clone 4G63t auto
1992 Talon TSi
1990 Talon TSi
1995 Crown Vic
1993 Ford F-250 BBF
1987 Chevy Sprint Turbo

Oh my, I used to keep the 4G15 FAQ but I can't remember; what will compression be like when swapping a 12V head on a X1 bottom end?

_________________
Got rabies?

what other kind of pistons would I get 11.5:1 CR ??

i want to race, i was thinking about corolla pistons ( olds models ) has a nice pistons.

any ideas??

i guess 10.5:1 its ok......... but if i want more, which ones should I get?

_________________
Stock Sucks...!!
Mods List:

Custom cold air intake
Iridium Sparks
NGK sparks plugs wires
2" exhaust and moffler
ACCEL Coil
240cc inyectors
52mm TB
K&N filter
Elantra BRAKES ( upgrade )
195/50 R15
2.5" lowering springs
Ate. brake Fluid

A bit of a threadjack to be sure, but it's kinda' on line regarding the topic at hand.

These '86-'89 X1 Excel pistons work in a 4th gen 12v 4g15? Just bolt 'em up to the OEM Mitsu connecting rods and you're good to go with 10.5-1 compression?

G.

I think so. Maybe they even work w/ the 5G engines. IIRC they didn't change much internally when they made the transition form 3G 4G1x engines to the 4G ones.

_________________
Got rabies?

Is the Hyundai X1 engine an actuall 8v g15 Mitsu engine? Same block, crankshaft, rods and pistons?

Were they supplied by Mitsu for installation in those early year Excels?

Can you confirm as to fitment into the 12v engine? In regards to wristpin size, and proper deck heighth, sufficient valve clearance, etc, of course.

Thanks Ethereal,
But one needs a more definite answer than, "I think so," and "Maybe...."
Believe me though. I value anything that you can pass on. I highly regard you as one of the gurus when it comes to info and experience with our cars.
G.

The Excel's engine is indeed the Mitsu 4G15, just build by Hyundai.

_________________
Got rabies?