Changing Pistons

[Aslet]

Has anyone changed the pistons in a 944NA to ones from an '88 of to Euro spec pistons. I have my engine out and apart and was thinking if I could get the higher compression pistons and another 10 or 15hp it may be worth doing. Overall getting '88 or Euro pistons are, well, hard to find. I was thinking of getting some J&E pistons that are 100mm with the same top as the higher compression pistons. It would cost about $800 for a set that are properly coated, but they would be new and made exactly how I want them. Any thoughts? Anyone know if I did get pistons made to the '88 pison specs if this would increase my compression to the 10.6:1, and give me more hp like the '88 944?

THANKS!

[krystar]

u'd need to get the 88 DME to make proper use of those pistons.

or u could go all out and get some 13:1 CR pistons and run a standalone engine management system like microsquirt.

[v2rocket_aka944]

88 pistons were 10.2 throughout the world, iirc 158 hp
euro pistons 82-87 were 10.6 and those engines were rated at 163hp

either way youd need the matching dme and better gas

[Schumi]

That same amount of horsepower can be had for a fraction of that price in the form of one of Russel's 944 MAX chips.

Raising the compression without swapping in the ECU from the high compression motors or retuning the chip somehow will gain little performance.

[Rasta Monsta]

I say go for it, as long as it's apart. . .I just put a set of slightly higher (euro) compression pistons in my 931, also from JE.

You might also call Diamond Racing. . .they come highly recommended by a buddy of mine who races 2.0s.

[HondaDustR]

Do you need the whole DME computer, or just the chip? Some 88 spec pistons AND Russel's 944MAX chip would be even better. Just buy the 88 version.

If you find OEM pistons, they have to be the same tolerance group as your cylinders.

[Aslet]

Needing the different DME makes sense. I was planning to at least get a late model DME and a chip. I will just make sure to get a chip for an '88. Is the actual DME any different? I've been thinking about a different DME since I have an early car with no chip. I know Russel said I could get a DME from a late model car and just plug it in, then put a chip in that. As long as I get a properly programmed chip for the compression of the different pistons it should work fine and get me that extra horse power, correct? (I think I would go for the 10.6:1 compression like the Euro cars).

Other items I was planning on using:

ENGINE:
Crossdrilled and knife-edged crankshaft
Lightweight fly wheel
MSDS headers and 3" exhaust (no cat and hi-flow muffler)
Late model DME and chip that works with my system

SUSPENSION:
Already have Koni yellows, 300lb springs, and 27mm torsion bar
M030 sway bars w/ reinforced mounts and custom Derlin bushings

DRIVETRAIN:
Spec cluth set
Rebuilt tranny
LSD


Any more input about this setup?

[Rasta Monsta]

I would take the money for the machine work on the crank and spend it instead on a crank scraper/windage tray setup from Ishikara/Johnson. My buddy just had his knife-edged, and to say his motor has lost some of its buttery 2.5 smoothness would be an understatement.

[John_AZ]

Originally Posted by Aslet

Needing the different DME makes sense. I was planning to at least get a late model DME and a chip. I will just make sure to get a chip for an '88. Is the actual DME any different? I've been thinking about a different DME since I have an early car with no chip. I know Russel said I could get a DME from a late model car and just plug it in, then put a chip in that. As long as I get a properly programmed chip for the compression of the different pistons it should work fine and get me that extra horse power, correct? (I think I would go for the 10.6:1 compression like the Euro cars).

Other items I was planning on using:

ENGINE:
Crossdrilled and knife-edged crankshaft
Lightweight fly wheel
MSDS headers and 3" exhaust (no cat and hi-flow muffler)
Late model DME and chip that works with my system

SUSPENSION:
Already have Koni yellows, 300lb springs, and 27mm torsion bar
M030 sway bars w/ reinforced mounts and custom Derlin bushings

DRIVETRAIN:
Spec cluth set
Rebuilt tranny
LSD


Any more input about this setup?

Might want to consider buying a Kevlar cam timing belt. $130+-

I have read that the light weight FW and the weight off the crank by knifing will stress the OEM cam belt and eat the cogs upon startup and high rpm shifting.

GL
John_AZ

[Sterling Doc]

Many 944 Spec racers run '88 pistons or shaved heads to et to 10.5 compression on early ECU's, and make good power safely. The late ECU's are quicker to pull timing when it's hot (prob d/t higher compresssion giving less margin), but if you run good 93 octane gas, you should be OK with any ECU.

[Aslet]

Rasta (or anyone): I have seen the crank scrappers, do they actually do anything? I will be installing an oil pan baffle, but I have read the scrapper also helps the oil situation.

Sterling: I already run 93 octane, even though I know it doesn't do anything for the car. Doesn't the ECU need to be programmed to what compression you are running to use the power?

[Rasta Monsta]

Interesting testimonials can be found HERE. . .

[Aslet]

Is this what you suggest I get?

RS BARN: Performance Parts & Engineering

[Rasta Monsta]

I have never seen that company before, but I like the prices. I just put an I-J scraper in my 2.0, and it was a pretty nice piece.

[Aslet]

If you install a scraper would I still install an oil pan baffle? Also has anyone done that oil pickup reinforcement? I have heard that it can be a weak point...

[HondaDustR]

Man! Where was that site when I had my oil pan off! $80 would easily have fit into my budget, and to have a real crank scraper!

I would get the scraper and the oil pickup bracket if it was me. If I was building a spec race motor, the windage tray looks good, but kind of pricey, but then again, it might be money better spent than knife edging the crank. Full on knife edging and an aluminum flywheel would probably be too extreme unless it's strictly a track motor. Driving in traffic with that would probably suck big time. The medium lightenning package at Lindsey Racing looks like a good compromise. I almost decided to go for it. That plus the scraper would be awesome.

[Aslet]

My only concern is that a knife edged crankshaft varies depending on who does it. I will have to confirm that the knife edge scraper would work with how mine turns out. I also am going to add an oil pan baffle. I think the scraper, baffle, and pickup reinforcement would be a good combo. I'm not so sure about the windage tray.

Back to the pistons though. Anyone else running 10.6:1 Euro spec with 93 octane and have good results? Also, does anyone have experience with J&E pistons? I can get a set of pistons made to any spec and coated for around $800. Considering used Euro ones are almost impossible to find and '88 ones are around $500 for a set and they are used so they may have issues...

[Aslet]

Also, do the early 944s have knock sensors? That could be an issue if you raise the compression...

[Sterling Doc]

None of the 8V 944's have knock sensors except the Turbo. Nothing needs to be reprogrammed for the higher compression - you're not adding any fuel or changing the ignition timing. The only issue you have to be careful for is detonation - should not be an issue with good fuel & plugs.

I'm sure a custom chip could get you some gains, but it's not necessary just to be able to use high compression pistons.

[HondaDustR]

They may be able to make a custom scraper if it turns out that different. I would go with the J&E pistons, since you can have them however you want them, they'll be brand new, and they're not a whole lot more than used 88 pistons.