V2Rocket

No, the NA manifold curves in on #4 to clear the AOS and it gets close to the fire wall too.

Here’s the 944S AOS hybrid thing he mentioned

https://rennlist.com/forums/944-turbo-and-turbo-s-forum/1080785-oil-filler-relocate-alternative-option.html

regarding plenum volume, there are some guidelines but don’t lose sleep over a certain volume to displacement ratio. Go with what fits… Look on YouTube for “kegalodon” for some entertaining info.

JRP944

I suspected that might be the case, but seemed like a nice solution to keep it stock looking and keep a real oil fill. I know the Lindsey Racing relocation kit exists and plenty of others have done similar things with a simple hose and filler cap so it's not the end of the world.

Thanks for bringing that one up again. I actually have it in my subscribed threads.

It's funny how heated the topic of plenum volume and design can get. You get responses from some who swear up and down that if you don't get it 100% right and perfectly designed that it just will never work. Then you get responses from others who essentially say the same thing as you did - make what fits in the engine bay and roll with it. I know Michael Mount has said the same thing in some of his threads and obviously any production BMW M-car had compromises in there somewhere for cost and manufacturability.

JRP

V2Rocket

I've seen alot of that too over the years. Generally there isn't 1 right answer and most people don't really know what they're talking about.
Lots of info gets quoted and parsed and context gets lost. Sure, some engines run great with a plenum that's 400% the engine size but those engines have an inlet restrictor to meet class rules. Not really relevant for cars without a restrictor.

A NASCAR makes 900hp at 8500rpm or so out of a 360" engine, with a plenum under 200". But listening to some folks online, that's all wrong...

962 kid

I definitely get the plenum volume thing, my thought was more about trying to make it so there is adequate clearance around the velocity stacks. Packaging trumps all. Have you considered expanding the plenum downward, like an S54?



As far as engine management goes, the stock ECU, at least with the stock mapping method, probably won't work. Because the 944 doesn't have a TPS(just an idle switch and a WOT switch), you don't get any accel enrichment. Having mapped a lot of ITB cars, accel enrichment makes or breaks them. I'll be happy to be wrong, but I'd expect a fight to make it work.

All in, it's very cool. I hope to see it all come to fruition!

JRP944

I created some preliminary designs where I did extend the plenum like the S54. My concern there is that it won't fit the 951's. It would be great to have a system that worked on both NA and turbo cars to expand the product reach. Definitely more work to be done here.

Thanks for the support!

JRP

Tom Pultz

JRP, you might want to check out the thread "Shaftless Throttle Bodies" in the 944 Turbo section over on car pokes. Very interesting discussion.

Chalt

I wanted to comment earlier on this thread but I thought I would reveal my ignorance, I went and read a little about ITB's. At least I know what they are now. They look nice.

Buuuut, what I wanted to ask then is the same, now.

Is this a cool engineering project, mainly?

Reason I ask is, everywhere I have ever read, is there is little you can do to get big power gains on a 944 NA. And, people who have done so, have spent a lot of money for not much gain. The conventional answer is just go buy a Turbo, OR, if you are into a little bit of problem-solving/fabrication/punishment, swap the engine for an LS.

If it is for a cool engineering project, nice aesthetics and great throttle response, I do get that. Beautiful design, and looks like you are having fun designing this. But won't the power gains be modest at best for an NA?

Forgive my ignorance on this, I know I am unwashed, unclean.

JRP944

Thanks for clueing me in to the Car Pokes thread. I had heard of the site but never visited. Looks like they are planning to use the AT Power throttles, which are very nice indeed, albeit expensive. Though I guess when you factor in what they are for the price, it's not so bad. They ooze quality.

JRP

JRP944

Ha, you're not unwashed or unclean! Good questions and no reason they can't be covered here even if they've been answered in bits and pieces via other threads.

You are correct - the gains on a standard NA will be very minimal in the horsepower department. The benefit is more in the increased throttle response, the intake sound and of course the cool factor. A really snotty NA motor with a hot cam would see far more benefits. Perhaps that is the dream...

I have an NA car, so that is my test platform. If I had a 16v, I'd be starting there instead. The benefits to the 951 and the 16v cars will be greater, so the hope is to eventually expand to those applications. Essentially I would like to see the NA kit and the 951 kit be the same, so I still have some things to work out in the design of the plenum. The 16v would use a different inlet manifold, different throttle body size and different ram tube extensions and plenum base. The basic throttle body design is the same, just machined open larger with a larger throttle plate.

Honestly, seeing some ITBs on a 07k converted 944 would pretty cool. The design I laid out works well for a 5-cylinder since each throttle is separate and can be spaced appropriately.

And yes, at the end of the day it is a fun engineering project. I think ITBs are cool and like designing stuff so here we are.

JRP

Chalt

That all makes sense, thanks for the kind answer. It makes sense that your goal is kit for the 16v and the 951 also. Really cool project. Didn't know the intake sound would be different!

sm

I find most cars, even a Honda Accord, is more than fast enough for public roads. If you can bring this product to market and enhance the driving experience and sound of our motors, similar to what the CSL intake plenum has done for the s54 BMW motor, then I think that’s a win. I have a 16v intake from the 968 I can lend you.

Chalt

Okay, so I just youtube searched "bmw s54 engine sound" on youtube.
I listened to this one:

So are those BMW's naturally aspirated? Is the sound because of the ITBs or mainly aftermarket exhausts? Are the ITBs stock on the s54's?

sm

The stock CSL car allegedly has one of the best induction sounds due to the carbon fiber intake plenum. It’s s54 motor does have ITBs.

See the ~2:00 mark of this video:

JRP944

This quoted video above is a better example of the induction sound of the ITBs. The video previously posted was more exhaust sound since most of the shots were taken from the rear of the car.

Here's a decent example of ITBs on a 16v 944:


JRP

JRP944

I just might take you up on that. I just discovered there is a place down the street from me that provides 3D scanning services. I think I'll take them my NA manifold stub today and see how well they scan it. I measured it and modeled it myself, but being able to scan a whole manifold locally would be a huge help.

JRP