Ed MD

Carl, I didn't mean to offend. Yes, I acknowledge the intake pulse/ water hammer effect, what ever you want to call it, when the intake valve slams shut, a sound wave echoes back up the intake runner. Sound a basically a high frequency pressure pulse. If you time it right, and use resonance to your advantage, this sonic wave can be used to pressurize another cylinder. Chrysler used this technology back on the 1960’s. I should have stated "that in general there is a vacuum on the intake side" . The question is- is this significant, and to what extent, I would think that if so, more work would have been done such what has been done on the exhaust side, like the exhaust throttle valve (actually Yamaha called their's an EXUP valve) to compensate for the reflected pressure wave travelling backwards towards the engine on the exhaust side, i.e. reversion.And I now understand the trepidation express by Bigs at the beginning. Ed M

Carl Fausett

No worries, ED MD - you did not offend in the least bit.

Sorry Tony - I thought for sure I remembered some posts of yours with
EGT on each cylinder. Oh well.

Yes, Louie - I too would have liked to see some radiusing of the intake ports at the top in Andy's manifold. Sharp corners always cause turbulence and must be avoided. Yet, when the "runner" is basically the length of the port in the head - I do not know how much a bell would matter anyway.

Fabio421

It's nice to see that this thread has remained civil. That has been a rarity among boost threads in the past. Good work gentlemen . On behalf of myself and countless others, thank you.

Now, I think I understand Carls posts as saying that they both have stengths in a different rpm band. And that because of the TS's mounting fashion, it may be losing some added benefit, that could be had if the tuned runners remained.

How much would you gander could be gained by this tuning of the runners and are we at the point where it makes sense to explore it. I am sure that there are gains to be made, but at what cost per hp/ ft. lb ? It is a very interesting subject.

What if you could somehow mount the blower in place of the spider on the 16v cars for instance? I am using the 16v cars for an example because I think it would be much easier to fit under a stock hood. Putting it there would allow for the use of the tuned length runners. I'm sure theres a way it could be done. That would be the cheapest way to see what gains are to be made. But there isn't a TS for the 16v cars to compare it to yet. But they say they are working on it. [Sigh] So I guess we would just start another apples to oranges comparison with that.

Carl Fausett

Fabio - your killing me! We have had a SC kit for the 16v cars that preserves the intake runners for 4 years now.....
....sometimes I just don't get it.

Anyway - as to installing a twin screw on the 16v heads - I didn't try it because:
1) designing the manifold to allow for spark plug access on the 16v cars would be challenging
2) the CIS cars have mechanical injectors - a twin-screw would mean that the owner would have to have the $$ and be willing to convert to an aftermarket electronic fuel injection system, (one of our design goals was a simple installation - this alone adds complexity and cost) and
3) my strong preference to retain the unequal length intake runners to maximize the MPG and the power band.

BTW - I looked up the Whipple specs and it looks like some of them will go above the Eaton in RPM's quite nicely. All the sites were vague on what the max rpm of their twin screw was, but they advertise up to 14 psi at 6,000 engine rpm - the Ford Mustang has a 6.5" crank pulley - my math says the Whipple is turning about 16,000 rpm at that point. That should be plenty.

sweanders

Nope, a massive torque curve is normal for a turbocharged engine. Just study dyno charts of 951 with different typ of intakes - they all give an early torque curve if the turbo is sized properly.

Regarding the choice of TS, Centrifugal or turbo it is not very hard to decide if budget is not an issue. A turbo makes more power than the other because of less parasitical loss, a TS is a very efficient supercharger with a very big power plateu while the centrifugal would never be a personal option for me.

Bill Ball

Tony:

Thanks for trying to clear that up. Carl had me worried here for a moment, particularly with the level of details he presented about your problems and tuning struggles. I was pretty sure he had it wrong, especially with the individual injector tuning.

I would think if leanness and high EGT in one or two cylinders getting more air than the others were happening, you would be having detonation in those cylinders. I believe it is a potential concern or I would not have paid any attention, but many things in life are potential concerns. The only time I've had detonation was when I bought some Safeway gas. Never experienced it otherwise, even racing out in the desert in 95 degree heat and 170 MPH with no intercooler and the AC running. Of course, my kit is modest and not too stressful. If Tony has not encountered these issues in Las Vegas, I can't get real concerned.

Carl Fausett

Enjoy your 928, Bill. And don't let me make you worry about it.
That is not what I was setting out to do. Just trying to educate, that's all.

If Tony does not have twin-screw individual EGT readings - does anybody else?

mspiegle

Thats what I thought! I was about to send you a PM and inquire about some of your research because I didn't remember you making any of that public.

Bill Ball

Advice taken!

hacker-pschorr

There you go opening that can of worms. If money is no object, I'm sure most would opt for a stroker and forced induction. Three stroked / SC 928's are in the making up here in GB. One has been running all summer, the other two are in various stages of engine assembly.

Bill Ball

Hey, do we know the owners or are they too busy for all the desk jockeying here?

Tony

I would love to have individual egts on my engine..just to see whats happening. I know BLOWNBEAST has them on his CS engine. ..I saw them at Sharktoberfest. I believe he got them from Prof Ott. ? They screw right in below the exhaust ports into a factory fitting.

Do you have a a set Louie? or can you point me in the direction on how to make them? PM if you like.
Are they K type as i already have a unit to read the temps...not all at the same time but i can get an idea of whats happening at least.

Mike. If i was tuning injectors individually, it would not be somehting i would have kept hush on thats for sure. It would have been quite a feat for an individual to do. I think the closest we are getting to that now on our cars is the work being done by John Speake.

Its all good guys...never been better for this car as far as HP options

I cant say enough how the TS has woken up my 2.20 auto off the line.

ErnestSw

I think Sterling has EGT sensors at each cyllinder.

mspiegle

John definately deserves a few more of those:

SharkSkin

This thread has been a great read. Thanks to all! One little nit though:

Actually the turbine boost in the M1 is the various compressor stages of a gas turbine engine! No pistons in that puppy at all,. When you're ready to offer a retrofit for the 928 let me know, I'll see what I can do about knocking over a few banks to fund such an appropriate shark upgrade.