R/TErnie

iTrader: (32)

I've been thinking about building my engine for the past year or so and I've been struggling with deciding between 4G63/4G64, 88mm/94mm/100mm strokes, Short compression heigh pistons, con-rod's based on weights, and compression ratios. These are the questions that most of us have to answer when building a new engine to take our new found power thirst or to replace a failed previous engine. I wanted to focus on picking stroke... or ultimately the displacement of the engine you choose.

Some Basics that every can agree upon...because they are facts of physics and not a matter of opinion.
- Horsepower is directly related to acceleration (not torque)
- The higher you can shift your powerband in the RPM range the more power you'll make for the same amount of torque.

To maximize acceleration, you must maximize horsepower... to generate the most horsepower you need as much RPM as possible. This brings us to our limiting factor... Engine Speed (RPM)

Ok... Now my thoughts shift to the boundaries or limitations of any given setup. A few main points that I focused on for the Evo are....

- Valvetrain Rocker arms and valve float.
Depending upon hardware these may limit you to 9k or 11k RPMS

- Clutch/Transmission/Shifting.
Any trying to shift an Evo gear box at 9k+ will know what I'm talking about.... I state this as a limitation because dog boxes and Tilton carbon twins aren't exactly affordable or reasonable in a street driven car. No 3k dollar rebuilds on a clutch that lasts less than 10k is NOT reasonable for 98% of the Evo owners out there. Picking a clutch that is streetable, yet is shiftable at high RPMS is difficult since the two have conflicting requirements of design. I consider the Exedy Twin limited to 8500RPM(maybe even less) shifts (specifically the 1-2 shift). The 7.25" clutches have a much lower PMOI and therefor shift much better at higher engine speeds. From feedback on the forums the Quartermasters and Tilton 7.25" clutches shift well to 9k+ My analysis assumes you'll be using QM 7.25" Twin. This means we'll be limited by our clutch combination in terms of shiftability at anything over 9500RPMs or so.

- Gear Ratios
By changing the operating range of any engine you also change the maximum speed that each gear can produce. This may require a change in final drive or a 3/4 gear change. None-the-less this is a $1000+ decision. If you plan on drag racing, having a gear box that allows you to pass the traps at a reasonable RPM is important. Depending upon the power you're planning on making you can estimate the trap speed and then back calculate the RPM required in 4th gear to achieve that trap. This is VERY combination specific, but is an important factor for everyone to evaluate.

Of course Rods, piston weights, camshafts, turbos, engine dampeners, and bearing life will affect how high your engine can make power/survive at... but these components can be selected at a reasonable price during the build to suite your stroke/displacement/RPM operating range.

*****
From this quick evaluation of the RPM limitations of the Evo... I've come to the conclusion that for the limiting components that I have determined are acceptable to me 9000-9500RPM is the highest I can reasonable Rev and Evo without running into large issues.

I look at stroke quite simply. Run the largest stroke you can while not limiting yourself by RPMS. Using Magnus' nice chart here...

http://www.magnusmotorsports.com/tec...EngineList.pdf

Then the following combinations meet or exceed my proposed limit of ~9500
4G63 w/ 94mm crank (just under 9500)
4G63 w/ 92mm crank 9500
4G64 w/ 94mm crank (Just under 10500)
4G64 w/ 92mm crank 10500
4G63 w/ 88mm stroke 10,500
4G63 w/ 88mm stroke (156mm rod) 11,000
4G64 w/ 88mm stroke 11,000

Following my previous optimization concept.. pick the largest discplacement engine with the best rod to stroke ratio. Obviously the 4g64 will have a better R/S ratio for the same given stroke in a 4g63 engine due to a 12mm taller deck. Further more the 4g64 has a STD bore of 86.5mm compared to STD bore of a 4g63 of 85mm. Therefor the 4g64 block for the same given stroke will have more displacement than the 4g63.

4G63 w/ 94mm crank (just under 9500)
4G64 w/ 94mm crank (Just under 10500) <-- better r/s ratio and MORE discpacement.

4G63 w/ 94mm stroke
85.0mm bore 2133cc (STD)
85.5mm bore 2159cc (+.020")
86.0mm bore 2184cc (+.040")

4G64 w/ 94mm stroke
86.5mm bore 2209cc (STD)
87.0mm bore 2235cc (+.020")
87.5mm bore 2261cc (+.040")
*** be weary of core shift with 4g64... the cylinder walls become much thinner when boring the cylinders.***

As you can see...when each block has been bored .020" the minimum amount of bore required when building a used engine block... the 4G64 has an extra 76cc's of displacement and according to magnus capable of 10-10.3k

From this analysis I'm beginning to think a 96mm 4G64 would be best suited for my setup. The RPM capability of the 94mm 4G64 exceeds my setup's capabilites by about 1000rpms

96mm stroke 87mm bore 4G64 would be 2283cc another 47cc's (or half a tenth of a liter) and have a maximum engine speed of around 9300RPM (for reference a 85.5mm 4G64 w/100crank is 2297! 14cc's bigger but rev limited to 8k)

In essense you'd have the displacement of a 2.3L 4G63 stroker, but the Rev range of a 2.2 4G63 (92mm stroke) Extra discplacement without the loss of Rev range...yet not excessive rev range that is not suitable for the other components on the Evo (transmission valve train etc)

My point of this long winded thread is that I've come to the realization that all of all the engine options available for the Evo... none of them suite my needs perfectly. My solution would be to have a custom 96mm crankshaft made with rods and pistons. There may be some combination that allows me to use a shelf 156mm rod with a custom piston... or a custom rod with a std piston... or custom rods and pistons. I'd have to sit down and do the math.

Well well... during writing this I realized that someone already did this...
I think the AMS 2.3RR is very similar to what I've spec'd except for one detail... the stroke. They say their engine is 2270cc which with a 4G64 (extended deck) and .020" bore and a 95.5mm stroke you're EXACTLY 2270cc.

I would think having a slightly lower RPM limit 9100 or so would be acceptable (shift-ability) and would be attainable with a 96mm stroke, custom 154mm rod

Judging from the R/S ratio's of the two engines that are evenly spaced on either side of my RPM target (9k)
100mm 4G64 w/156mm rod = 1.56 8500RPM LIMIT
92mm 4G63 w/150mm rod = 1.63 9500RPM LIMIT

My ideal R/S ratio will be between these erring on the higher r/s ratio side... approximately 1.60 R/S ratio.

I did a little excel chart to help my decision process.


Now that I have my GREAT idea... let me know if I messed up anywhere and what you think?

I would have magnus put a custom setup together for me

JohnBradley

iTrader: (30)

Eric,

I would use a 97mm K1 since it is (or was available) and a normal length rod. That way you only have 1 custom part to order instead of 3. I had thought the RR was 86.5 x 97 but I might be incorrect I havent run the math yet.

Since you are planning on being RPM limited because of the gearbox, the 97 and some 156s should work really well.

just my thoughts.

p.s. -got the bore sizes an extra 10mm on the 2.2 and big 2.2...should be 87

apagan01

iTrader: (299)

Gl, i like how you are doing your research for an educational decision

R/TErnie

iTrader: (32)

Thanks for the look out. I somehow missed that lol

A 86.5 with a 97mm stroke would be a 2280cc

Looking at this... I think I've messed up my deck height calculation. I didn't half the stroke (I should be using 44mm instead of 88mm)

JohnBradley

iTrader: (30)

235mm and I look for .010- 0.000 down the hole and then a .040-.051 gasket to keep at least 40 thou.

miragevo

iTrader: (21)

How about use a 100mm crankshaft and custom 159mm rod and custom piston that has the pin shifted up 9 mm instead of the 6mm std. stroker piston. It's cheaper to get rods and pistons made rather than crankshafts, I would think. This would net you a 1.59 rod stroke ratio. I think Magnus sells 159mm rods and I spoke to JE and they can safetly make this pistom. Aaron...John Bradley uses a similar piston that shifts the pin up at 9mm.

JohnBradley

iTrader: (30)

Just to add, I cant get custom cranks done in stroke (as can anyone else I assume) so it might be that the AMS 2.3RR is a slightly shorter stroke. They might leave the .5mm (.020) for deck clearance or something and then run a slightly normal (as in whole measure) rod length.

R/TErnie

iTrader: (32)

235 @ .009" down the hole is 234.702mm which is what I put for deck height (which it's technically not, but it's the total length of the components for this analysis)

miragevo,
I added your idea to the list. RPM limit shows to be still too low. we're talking minimum 9k. Not to mention that's a custom piston with the wrist pin WAAAY up in the oiling ring. Funny thing is that it's the EXACT same piston dimensions that Aaron had to run in his 2.2L LR 4G64! I highlighted them in gray. Your concept allows 500RPMS less than my current best option.

The 97mm crank with the 1.13CH "stroker" piston seems to be the best combination with a custom length connecting rod.

**** Turbo Discussion *****
My theory for this built block is to make a 6262/HTA3586 that hits peak torque @ 5k and carries to 9k. Here's some collected info that may help support my theory. Maybe I'll need some FP5R's or some those special S2R's

I look at this dynochart... Precision 6262 on a built 2.0L (thanks GST Motorsports) 500whp by 5600 RPM and it will carry power past


Another 6262 on a built 2.0L This one on a dynojet... showing the turbo @ 37psi carrying to 9k.


John Bradley's dyno chart from going from a 2.0L to a 2.2L ON 92 PUMP... just imagine what a 2.3L would do that could rev to 9k? Note 3586HTA

miragevo

iTrader: (21)

R/TErnie,
On a positive note, my idea also nets you the most displacement for possibly better spool up. The custom piston also looks just like the AMS 2.3RR you have in your first post. I spoke to JE about this a while back as well as discussed it with Aaron and I think this is the way to go as far as pistons are concerned. I did some research about pin placement and read that the higher you can get the pin in the piston the better.....I think the piston that Aaron runs is "THE PERFECT PISTON". They are also pretty light too. I would use this piston and work backwards from there. If you do this while keeping the stock readily available choices of 100mm crankshafts in mind, it lands you at a 159mm rod...and a slight compromise in rpm capabilities, but netting you more dispacement in the end.

miragevo

iTrader: (21)

You would need a custom 157.5mm rod if you decided to go with the 97mm crank

R/TErnie

iTrader: (32)

I see your point miragevo. I guess I need to rework the analysis sheet for a piston with a 1.012" Compression Height versus a 1.13" Compression height.

the previous analysis used the shelf stroker piston...

Time to get back to the excel charts! Thanks for the input.

Ted B

iTrader: (6)

Maximizing hp means moving peak VE (torque) to the right, and that isn't easy, especially given a motor (4G63) that wasn't especially engineered for the purpose. And of course, even where one does this, everything to the left suffers (which doesn't matter so much if it isn't a full-weight street car).

Likewise, moving VE to the right while increasing displacement by stroking exposes weakness in port flow while increasing mean piston speed for a given rpm simultaneously. Once MPS reaches 25 m/s, things tend to wear out in a hurry. FWIW, the 'max rpm' for combinations as listed by Magnus are well beyond that figure, and lie squarely in the zone where dealer pricing on replacement parts, some in-house machining capability, and deep pockets become very important. Be forewarned.

Unfortunately, the 4G63BT will never be an F20C, and one fairly significant part of the disparity lies in the head. As we are volumetrically limited, we have to compensate by increasing (boost) pressure, and that raises a different dimension of issues.

I didn't get if this was a dedicated drag car or otherwise. I think you'll find however that the real world differences between some of these configurations is like splitting hairs in a relatively expensive fashion.

Just my $0.02.

Steve93Talon

iTrader: (5)

We're running an S362 in a divided T3 .85 housing on a built 2.0 in a 1G DSM, seeing full boost around 5200 rpms, making 700+whp and still at mid 600s to 9k. A similar setup on an IX should spool a bit quicker. A 2 liter with a properly sized twin scroll setup is where it's at.

R/TErnie

iTrader: (32)

Ted,
I ran into the head issues with the 1st gen neons... going from 2.0L's to 2.4L and having to spend a lot of time in the cylinder heads to get them to flow as they should. The camshafts required to get a 2.4L power band to behave as it should...were astonishingly large in comparison to what was being ran on the 2.0L engines. I also understand that valve area will play a large role in achieving the power at the given engine speed.

If I lock piston speeds to ~26.5 meters/sec....
88mm - 9034 RPM
92mm - 8641 RPM
94mm - 8457 RPM
97mm - 8196 RPM
100mm - 7950 RPM

In this case I really only have one winner that meets the requirements... 2.0L and I could do that with a long rod 4G63.

I guess this NEW chart... needs to be updated with RPM limits based on piston speed and not based upon my interpolation of Magnus recommendations.

R/TErnie

iTrader: (32)

Using the piston that miragevo suggested with the factory 88mm crank in the 4g63 block...