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Thanks- you guys have me thinking this out a bit more now. The heads are ported by 9M right at 42mm. The used 964 injector-stack housings that I have are 39.6. The new one is 1mm larger at 40.5. The aluminum manifold runner is 41.8. The bottle neck in my case is the bottom of the injector stack.
Rob- what stacks did you use with the RS intake and what diameter are they at the base? If I remember correctly the 993 stacks are closer to 42mm? Sucks that they all shrink with time!
Pete
edit- just for reference- the valves are 50mm/42.5 with 8mm stems.
Pete - the plastic center will mate directly with the aluminum manifolds
Fwiw- on the high horsepower build we just did- the decision was made to use the larger oem RS plastic intake manifolds as opposed to the oem plastic. The difference btw the oem plastic and aluminum are minimal. But the later RS gives you much bigger stacks and tubes leading to the throttle body (or from) and can therefore flow much more air. The heads have to be ported to match obviously...
Are you talking the large plastic plenum or the small intakes the injectors sit in? The PET doesn't show a difference for any of the engines other than the large plastic vs aluminum plenums although the parts did change from 1992 to 1993 MY cars parts ending in 03 vs the earlier plastic units ending in 02. It appears you are using the 993 fuel rails and some other bits.
I just cleaned and inspected my '93 intake and decided to use the leftover 993 bits I have from my 993 track engine (one day I will get it completed) The 993 plastic intakes (lower portion raise the injector up by 4mm so to spray fuel directly onto the valve guides for better cooling otherwise they are identical to the 964 version in size and dimension. The fuel rail also sits 4mm higher. I will look again at 2 Swoosh's cup car which should have the same setup as the ROW RS but I didn't see anything different than what was used on my C2.
Intake prior to cleaning. The plastic units do save considerable weight and have cleaner internal chambers. The cast parts are exceedingly rough castings internally.
I am using the 993 RS intakes which are 2mm larger dia on my track engine. Maybe these are the ones you are thinking of.
The engine is forced induction but using the 2mm wider 993 RS intakes allows me to mate it to the GT3 plenums which are 2mm wider than the RS intakes vs 4mm over stock 964 993 units. This is an early picture. A lot of changes still in the works. Switching to coil packs and intake has to be braced since there will be over 200 pounds of force pushing outward against the rubber couplers.
Are you talking the large plastic plenum or the small intakes the injectors sit in? The PET doesn't show a difference for any of the engines other than the large plastic vs aluminum plenums although the parts did change from 1992 to 1993 MY cars parts ending in 03 vs the earlier plastic units ending in 02. It appears you are using the 993 fuel rails and some other bits.
I just cleaned and inspected my '93 intake and decided to use the leftover 993 bits I have from my 993 track engine (one day I will get it completed) The 993 plastic intakes (lower portion raise the injector up by 4mm so to spray fuel directly onto the valve guides for better cooling otherwise they are identical to the 964 version in size and dimension. The fuel rail also sits 4mm higher.
My plastic intake in one of the above posts is an “03”. What I noticed compared to other images was additional bosses/standoff’s (993 air injection solenoid mounts and 993 air filter mount).. which made it even more work to shave, ugh...
The 4mm difference in the injector boss on the chimney’s is interesting. Explains why the 993 fuel rail seemed a little tight when mounting to the 964 version. Do the 993 chimney’s have a different inside diameter?
My plastic intake in one of the above posts is an “03”. What I noticed compared to other images was additional bosses/standoff’s (993 air injection solenoid mounts and 993 air filter mount).. which made it even more work to shave, ugh...
The 4mm difference in the injector boss on the chimney’s is interesting. Explains why it seemed a little tight when mounting to the 964 version. Do the 993 chimney’s have a different inside diameter?
So many changes it becomes confusing. Internally the 964/993 stock units are identical although the gasket has changed to viton now. The 993 RS intake has a (Correction from above) 4mm larger ID and 2.5mm larger OD if I did my math correctly, it also requires a different gasket which is more expensive than the intake. LOL Although I probably could have made the stock gasket work. My plenum is an 03 as well since it is a 93 MY I don't have an 02 to compare it to but I did a late 91 tip a while back and it was a bit different but can't recall specifically.
Here are the dimensions of the stock 964/993 intakes vs the 993 RS intakes. For some reason it won't let me post some pictures and rearranged them. the 1st and 4th are the stock intake dimensions and the 2nd and 3rd are the 993 RS.
Shoot... you had to go give me a reason to buy more parts! My stacks are a little cracked and I had to plane the base straight, but if it fits the 993 rail a little better and changes the injector direction... sounds like enough reason to do it before I pressure test the fuel system Thanks Anthony!
So the 4mm higher injector boss on the stack will interfere with the 964 injector rails? Anthony I do remember reading several accounts of the bottom ID (outlet) on the 993 stacks being 42.5mm vs. 39.5 on the 964. The thing is I already bought the 964 stacks so- guess I may have to sell them and pick up the 993 units if they do indeed measure closer to 42mm.
The RS units used for Johns motor are part number 993.110.722.00
I tried looking for more info- but couldn't find any on the web and am too lazy to repurpose my laptop for Porsche stuff at the moment- it's set up for "work at home"...
There is a custom made system run by solenoids that injects more air into the stacks- managed along w the motronic. It's a very cool setup. The car dyno'd over 300hp at the wheels, can't remember exactly. And over 300 ft lbs of torque. When you drive it- it feels like nothing I've ever felt- there is no sense from the motor at any rpm that there is any strain or any reason it wouldn't just keep climbing if you left your foot in it- no communication from the motor in any way that "it's time to shift"....super cool and incredibly easy to drive.
I tried looking for more info- but couldn't find any on the web and am too lazy to repurpose my laptop for Porsche stuff at the moment- it's set up for "work at home"...
These are the 993 RS intake stacks I was referring to and the same ones I am using on my 993 TT engine build. There are so many different little things used over the years and many 993 parts are interchangeable with 964 parts depending on need. I did verify yesterday the stock 993 intakes and the stock 964 intakes are identical in every way except the 4mm raised seat for the injector and 4mm of additional length of the mounting for the fuel rail. The numbers I posted are close to accurate and did find the stacks have variations by as much as 0.020" dimensionally.
My track engine should be going in the car this week. Finally but we have to fabricate the custom exhaust and intake, IC etc. So it will still be a while before it is up and running. My C2 engine is nearly done still waiting on some new fuel lines, hardware and painted fan. It will remain stock but I am using the stock 993 intakes and will be doing a custom dyno tune and chip burn. We expect to see 285bhp out of it on the mustang dyno but we will see in a few weeks.
Slightly OT but for those with ultrasonic cleaners is 30L the right size to go for for most part cleaning needs? Wish there was one you could drive the whole car into lol.
$%^&#@!&*((!!! Having a wonderful Saturday, gorgeous outside, garage door open, working on my Intake Madness teardown and mother f'er I screwed up (pun intended) on the last small butterfly screw. I stripped the damn thing. I was humming along and probably got lazy in my technique. By chance I have beautiful new Hazel screwdrivers that I use for precise tasks like this.
My years of work have taught me when this happens to walk away, think, and the re-attack the problem. In hindsight, I should have thought about squeezing the backside of the screws, they are spread locked in place on the other side, and then hitting everything with Kroil or other penetrant, then waiting overnight, clean-up with Brake cleaner in the morning, then try unscrewing. Note to others.
I have a screw extractor set I will try and then there is the drilling it out option.
1)First tried with my screw extractor bit, it would bite then release, too much tension still in the screw
2) I drilled out the center with a 5/64" drill bit, take my time, taking breaks, using cutting fluid, made it right through the center! Still no luck with screw extractor, tried to squeeze the end of screw, very tiny area to work in
3) Made the hole a bit bigger with 3/32" drill bit (I am sure the Europeans are loving the sizes here), then the screw extractor bit worked! Screw started turning no damage to shaft!!!
I was on the edge of my seat the whole time, simultaneously watching my baby sleeping (actual human baby) and wondering how this would turn out. Thanks for closing the chapter for me. (Note baby still 😴
05-01-2020, 12:25 AM
Thanks Anthony!
