Big Boost

Keith,

I got the above #'s from this thread:


https://www.evolutionm.net/forums/sh...d.php?t=103471


I am still in the process of gathering research for myself, which is better the 2.4 block or a stroker kit with a bore.

At this point, I am leaning towards the 2.4 block as the block is bigger and you are not changing the characteristics as originally intended for the stroke of the internals as designed from the factory. You would have to add oil squiters and this engine was not originally intended for boost.

Also, I do not know if the 2.4 block has the same oiling and cooling passages as the 4G63.

propellerhead

iTrader: (3)

How far can you overbore the 4G63? Can you punch it out to 86.5mm without issue? Magnus sells 4G64 overbore pistons in a 87.0204mm size so it seems that you can reduce the cylinder wall thickness quite a bit as long as your not planning on putting down insane amounts of power. FWIW, RnR is putting down over 600whp on a 4G64 with a 86.5mm bore so assuming that all other things being equal between the 4G63 and the 4G64, cylinder wall thickness might not be an issue.

Actually, the rod length and the stroke of the 4G64 are the same as that of a 4G63 stroker. The difference with the 4G64 block is that the deck height is 6mm higher. This is the reason that stroker pistons for the 4G63 have to have the wrist pin moved up 6mm, otherwise they'll stick up out of the block. My conclusion is that the 4G64 and a stroked 4G63 both "suffer" from the same rod ratio issues and redline limitations. I *think* that these issues can be mitigated to a certain degree by doing a careful build in terms of blueprinting the block and balancing the rotating assembly. By properly boring the cylinders round and perpendicular to the mains, ensuring that you've got the right piston clearances and using coated piston skirts I *think* you should be able to reduce the effects of the high side loading created by the low rod ratio. Despite what has been said regarding safe redlines, you'll never run a 4G64 up to 9,000 rpm for extended periods of time. A more realisitic safe redline for a built & balanced 4G64 is around 7,800 rpm.

At this point I don't speak from personal experience and I am merely bench racing. However, if I can come close to or match the displacement of the 4G64 by stroking and punching out the 4G63, I'll stick with the 4G63. It's "ready to go" with no modifications necessary to accomodate the oil squirters. You also don't need to hassle with the taller deck height and associated cam gear and cam belt issues.

At this point I have been working with Jackson Auto Machine to spec out my build. I would highly recommend that you give them a call and talk to Carmella or Jerry. You may end up getting roped into a half hour conversation but you'll probably get some good information regarding building a stroker.

Fourdoor

iTrader: (11)

Since we are both bench racing I will say that I agree with most of what you said
My view differs from yours in one area though. I would prefer the 2.4 block for one simple reason. I don't like putting the wrist pin that high up on a piston. You have to push the rings higher up on the piston, and put the rings closer together to get room for the wrist pin and in my view you end up with ring lands that are two thin and too high up to be as strong as I want in a very high HP / high torque motor. You could get around this by using shorter custom rods.... but that would make the rod/stroke ratio even worse and be expansive as well.

Later,

Keith

Fourdoor

iTrader: (11)

Dave is a former V-8 guy and I bet you he used the Standard bore and stroke numbers in the calculations and then converted to metric in the last step.... the metric numbers are much more precise in the published bore and stroke measurements so you end up with more accurate end results going metric from the start.

Later,

Keith

RnR Racing

iTrader: (23)

Yes, we are currently one of only 2 selling the built 2.4 blocks. They bolt right in and work very well for a very good price. On our shop car we made 630whp and 610ft lbs at 30psi. This was on a GT35R w/equal length manifold. We are currently reving the car to 8500rpm without any issues at all.


I will go into more detail when I get some time about the big advantages of using a 4G64 over using a stroked 4G63 block.

Big Boost

RNR,

I am bring this thread back from the dead, as there is another thread about a 2.4 vs a 2.3 stroker kit. I would like to hear about the big advantages.......

VTEC Killer

iTrader: (4)

The 2.4 is better because the block is taller, so that alone gives you more potential for displacement and the standard cylinder bores are larger, this alone give you a better rod ratio, rather then using the longer rods in the shorter 4G63 block.

evoviiiyou

iTrader: (3)

Email or call Switzer Perfromance Innovation and ask for Tym.
www.switzerperformanceinnovation.com

trinydex

iTrader: (12)

you're gonna have to clear this up for me and maybe show some proof cuz i keep hearing that the galant 4g64 has more bore than the 4g63 and it's not just stroked. set me straight.

why do you need oil squirters in this block?

btw... to answer the thread question... roadrace service also makes these to order.

ShapeGSX

Yes, and you can bore the 4G63 out to the same bore as the 4G64. The center to center bore spacing is identical between the two blocks. The 4G63 and 4G64 are essentially the same block, except that the 4G64 has a taller deck and the bores get machined a little larger.

trinydex

iTrader: (12)

and i have an additional question for propellerhead... wouldn't the 4g64 have a larger rod ratio... and hence not suffer from the limitations that you were talking about?

http://e30m3performance.com/tech_art...ratio/kin2.htm

and also according to this... it seems like changing rod ratios albeit are bad for the ring placements don't increase or decrease the rev capacity for the engine that much. it's like splitting hairs. they performed their example with 1cm of change and it only yielded about 200 rpm difference... if we're talkin' almost half that... i doubt there will be issues.

Ted B

iTrader: (6)

The difference in bore between the 4g63 and 4g64 blocks (if the info posted above is correct) appears to be 1.5mm, or 0.060", which could be significant if the cylinder walls in the 4g63 block do not have the same wall thickness. If this is the case, I would be most cautious about performing that size overbore in the walls of a motor that is going to be asked to make a great deal of power.

Additionally, swinging a comparatively large 100mm (3.93") stroke in that small engine creates a highly undersquare situation that puts substantial stress on the bottom end. Meticulous balancing and solid bottom end support (e.g. main studs and straps) are smart propositions.

And finally, as Fourdoor mentioned, lengthening the stroke with no changes in rod geometry is fine to a point, whereby the oil control ring is pushed into the piston pin, and the ring lands are so near the crown that the top of the piston becomes thin and less durable. I haven't seen a piston intended for a stroked 4g63, but the increased 4g64 deck height probably makes for a better/stronger piston.

Ted B

iTrader: (6)

The 4g64 block allows for maintaining the same rod/stroke ratio due to its increased deck height. In other words, it allows for use of a longer rod AND longer stroke, which preserves the rod ratio.

propellerhead

iTrader: (3)

Okay, it's my limited understanding that rod ratio has a larger bearing on piston sidewall loading (and subsequent wear) than it does on overall RPM limits. Naturally side load will limit maximum safe engine speed to a degree but what I was looking at was mean piston speed.

With a 100mm stroke, mean piston speeds in a 4G64 (or stroked 4G63) @ ~7,800 rpm is approximately that of a standard 88mm stroke 4G63 spinning at ~9,500 rpm. Also, the maximum g forces experienced as the piston comes off TDC with a 100mm stroke are MUCH, MUCH higher than with an 88mm stroke.

And yes, as Ted B and others have mentioned, without the extra deck height the wrist pin ends up being pushed up 6mm into the region of the oil control ring. In the motor I had built teflon support "buttons" or plugs are inserted into the wrist pin bores to help support the oil ring.

Ideas or comments are certainly welcome.

Ted B

iTrader: (6)

With a 100mm stroke, the piston travels 200mm/rev, which at 7800rpm = 26.0m/sec

As far as I can tell, the 88mm stroke equivalent at a piston speed of 26.0m/sec is 8863rpm.


For perspective, this is the same piston stress equivalent of a 5.0L Mustang GT engine turning over 10,000 rpm.