944NA Throttle Body Bore - How many mm?

[bergen bimmer]

I have a spare 944NA throttle body that was on my 84 Drivers Ed ride at one time. I know I had a enlarged , bored out one , but Im not sure if it was on the car when I sold it.

The bore on this one is 60mm. Is this the stock bore size?

Thanks in advance.,
Pat Leber

[fast924S]

Im not sure but Im sure someone will chime in, I would measure mine but I hand ported mine, So Im not sure what is.

[harryrick]

the number 57 mm comes to mind as stock...but don't quote me on that one.

[HondaDustR]

Originally Posted by fast924S

Im not sure but Im sure someone will chime in, I would measure mine but I hand ported mine, So Im not sure what is.

Hand ported? what did you do to it? I did a pretty good bore polish on mine, but didn't really change anything. I'm curious...

I don't know what the size is. All I know is that it's bigger than the openning on the end of the stock intake snorkel, which is why I detatched it.

[fast924S]

Well, I port matched it to the intake manifold which took a lot of work, I also took out the ridge that is cast into it and made it smooth, Then grinded down the rod in the center for better flow. It was me being bored and messing around Before I rebuilt it.









Still gotta do a little polishing, Also sorry for the bad pics, It was taken with a cell phone. Again not sure if its gonna make any difference, Just me playin around

I'Ll take some better pics soon

[HondaDustR]

Ah, yes..you reminded me that I did port match mine as well (for me it was waiting for the RTV to set after cracking open the AFM for cleaning). At first with a file, and later did a better job with a dremel (much easier). I did grind and polish the ends of the throttle plate screws flush with the shaft as well. I thought about smoothing the step on either side of the center section where the throttle closes, but haven't done that.







Now what would be cool if I had a method of calibrating it would be to modify a stock AFM by reducing the aerodynamic profile of the door and proportionally reducing the spring tension so it gives the same readings with much less spring resistance that has to be overcome, decreasing the restriction. And get a cylinder head and do a custom port and polish job, and, and...

I've done a few small engine heads with actually some very pleasing results, a OHV Suzuki lawnmower motor, a 16.5hp OHV briggs motor, and most fun of all...a Honda XR150 dirt bike motor. The bike was a totally different ride with the "new" head, and I also polished the carb, piston crown, and port matched the carb, intake boot, and cylinder head port. Hard work doing porting work mostly by hand, but it ran really well. I am a little surprised with the kind of sloppy fit and finish with the casting work, ect. for the bike and even the TB/manifold on the Porsche. I guess mass produced stuff just doesn't come out to high standards, and the expense is not worth the small gains for mass produced machines. I didn't expect much with the mower engines though...and there was much to be desired in their stock form They soon became the most unstoppable mowers I've ever ran.

I'm dying to P&P a 944 head. It would be a huge project, though, since it is x4 and they all need to be as identically done as possible. I like to feel like I did something out of the ordinary that makes my car a little bit better/more unique than a plain old stock sample, even if you can't see it.

[fast924S]

WOW, that polish job is sweeet. Yea I was very surprised on how the ports from the TB to intake are way off, Almost 1/4 of a inch overhang. I will get better pics when done, Im not sure what the step is for but I figure I will try it removed. That AFM idea sounds cool, Or you could just go MAF like I did.












This is before the rebuild

[HondaDustR]

Originally Posted by fast924S

WOW, that polish job is sweeet. Yea I was very surprised on how the ports from the TB to intake are way off, Almost 1/4 of a inch overhang. I will get better pics when done, Im not sure what the step is for but I figure I will try it removed. That AFM idea sounds cool, Or you could just go MAF like I did.

Yeah, makes me wonder what the intake manifold to head ports look like.

But the million dollar question...how much did the MAF setup cost? Is it possible to have a MAF with the stock DME?

[fast924S]

I checkout the Gasket between the intake manifold and head, It matches good on both sides so Im thinkin the manifold to head is ok, really hard to see. The Maf kit is a old kit from Huntley racing, Got it about 4-5 years ago, it cost $1200, came with the MAf and tubing, Fuel controler, AFPR, and a short band a/f gauge. Its is running with the stock DME but it does have a piggy back 4 knob fuel controler from split second.

What other simple things can we do to boost VE

Also what do you think that step is for in the TB

[HondaDustR]

Originally Posted by fast924S

What other simple things can we do to boost VE

Also what do you think that step is for in the TB

I don't know about simple, but the stock AFM is certainly one limitation, and I have heard the camshaft is a bit limiting for the high end (probably why these motors are so sick @ 3000 rpms, though). Then probably the cyl head ports.

As for the step, probably not for anything important, probably just a result of the casting dimensions giving some leeway for having to machine an exact bore size.
I'd be sure to only smooth the step and not to disturb the dimensions of the central area where the plate meets the bore.

[fast924S]

I agree, I think That step is for the machining of the bore for the plate, I made very sure I didnt mess with the surface where the plate seats. Im intrested to see how my engine runs after the rebuild with the JME cam shaft and other mods.

Besides the AFM, I think the next big restriction is the stock head, About a year ago, I ran a test with one of those PC dyno's That had all the info/demensions of our motors already loaded, It seemed to be very accurate with HP/tQ numbers, But I did notice from the data that the stock head with the stock cam/valve's just cant flow huge amounts of air to make alot more HP. The whole 8v with a single cam is the biggest problem, 16v with 2 cams is the way to make more power in NA form. But I hope to show some good dyno numbers with my 8v NA setup this spring

[HondaDustR]

A good porting job combined with a cam should pick up a few horses. keep us posted.

[fast924S]

DEF. Let me know if you find anything else that needs porting polishing or boring ;-)

[HondaDustR]

Check the intake manifold gaskets for proper dimensions. Unfortunately, this is probably only really possible to do well if the cylinder head is dismounted and the valves removed, but if you happen to be porting a spare head anyway, might as well pick up a spare manifold to match to it.. I've seen so many gaskets that are cut a tad smaller than the actual ports, or cut off center. Why spend 20+ hrs porting and polishing if a stupid piece of paper is hanging out into the air stream? They should be flush for best results. Too large is not good either, since it creates a ridge that will probably cause slight localised turbulence, but not nearly as bad as too small. I had to trim the AFM to airbox gasket so it didn't intrude on the airflow.

What really needs to be done is the inside of the intake manifold. It looks like crap in it's stock form, but it's so enclosed, I have no idea how it could be done. Not to mention it is sooo bad, it would take forever without some kind of thing other than fingers and sandpaper. It would probably be easier to just fabricate a custom one that isn't cast using pine cones. Or retrofit the tuned manifold used in the 968 by cutting the stock one just before the fuel injectors and welding the 968 part, which would also be apropriately trimmed to fit.

[gotmetal1]

Originally Posted by bergen bimmer

I have a spare 944NA throttle body that was on my 84 Drivers Ed ride at one time. I know I had a enlarged , bored out one , but Im not sure if it was on the car when I sold it.

The bore on this one is 60mm. Is this the stock bore size?

Thanks in advance.,
Pat Leber

Hey im looking for a bored out throttle body. for my 87 924s(for what i understand, also the same for the 944's) did you do it your self for the one you soled or did you get someone to do it for you.,,

[speedracing944]

You could always extrudehone the intake manifold.


Speedy

[dallas911]

Anywhere in CA I Can Bore my 1991 NA 944 S2?

Called a Few places , Nobody's Calling Back, Not at working.....

[v2rocket_aka944]

I had a 944 NA throttle body done by these folks a few years back. Quick shipping, reasonable price, etc.

Maxbore.com throttle body boring service and repair



Before anyone asks, no, going to a 60mm throttle was not worth any power at any RPM on an otherwise stock 944 NA 2.5L engine.
But I would bet there's some power to be gained on a 3.0L 944S2.

[dallas911]

Originally Posted by v2rocket_aka944

I had a 944 NA throttle body done by these folks a few years back. Quick shipping, reasonable price, etc.

Maxbore.com throttle body boring service and repair



Before anyone asks, no, going to a 60mm throttle was not worth any power at any RPM on an otherwise stock 944 NA 2.5L engine.
But I would bet there's some power to be gained on a 3.0L 944S2.

Thanks! I Called him & He's Working

I'll let you know how a 3.0 Does on Dyno, Tune Is:

KN Filter, TB. FVD Chip (not steve Wrong) High Flow Cat that's Emission Friendly....