m42racer

It's all about trying. Maybe it will work, maybe it won't. I do not think the problem will be Ignition. Years ago they said, "you will drop off the edge of the world if you sail passed the horizon". The problem with many in this business today, is that they still think the same.

I'm sure you can always have it better on paper, but quite often the engine never reaches the expected potenital, so the requirements are never pushed to the limit.

Jean

This debate is too technical for me, but if it helps, I have the stock twin ignition in my car. It runs faultlessly.

JJayB

Thank you for the math applicaation but I don't think there has been enough attention to the thermal load you would be developing if this is a sustained 8500 rpm. I know from my track days heat kills the power in these motors. When I see inlet temps of 145 f. I change my shift points down to 6200 for the motor to live. The 935 and 962's had water cooled heads which allowed for higher boost and rpm. By moving the power band upward in a turbo motor you are in effect moving the torque curve higher which would be great for dyno days, but you've got a slug at low speed. I can tell you've given this project a lot of thought, but I would like to know what you belive is the usable power range.

Kevin

JJ, I did not say sustain.. I am saying that we will hit 8500 RPM's or a few hundred shy.. Wouldn't it be something to strap the new Variable vane KKK turbo's on this engine? The turbine side is large enough to sustain 7500 RPM. I think that I proven that I can build turbochargers that provide a ton of power under the curve, we will have to stretch it up the RPM ladder a bit. As far as your inlet temps, you might need a larger intercooler. I think you are also running on the edge of the GT1's (you are running K16/24's?) efficiency range with your 3.8ltr if you are over 1.1bars.

Geoffrey

Heat is definately an issue. I have data from monitoring cylinder head temperatures and in my 3.4l engine it showed 170c at .7bar, 200c at 1bar and 220c at 1.2 bar. Based on information I could find regarding air cooled cylinder heads, the general consensus was that above 200c was a cause for concern. This engine was running 180-195f degree oil temps and 110-120f intake air temps. High compression N/A engines I see in the 150c range on the cylinder heads. On the dyno they loose quite a bit of power from 120c to 150c. It has been said that the 993RSR sprint engines, while making 408hp of PMNA dynos, would drop 20hp after a few laps due to the heat build-up. This is consistent with what I have seen.

Jean,

With your factory ignition, you are beyond peak torque after 6666rpm, so the cylinder pressure isn't as high and the demands on the ignition system are not as great. This is likely one contributing reason to the engine appearing to run fine. The thing with ignition systems is that while they run, how do you know that they are optimized? Right? Ignition systems are not a matter of working or not working, that would be worst case, however, they can be working and still be weak and not producing the potential power another setup could.

JJ, at 145c I would look for a more efficient intercooler, I don't like to see IATs above 140 and prefer them below 120.

Rickard 993 Turbo

Yes true, then the soloutin look like this

Geoffrey

if only it was that easy...

Rickard 993 Turbo

It's not that easy, it cost a lot of money, but there is a solotion

K24madness

Are your sure about that Jean? The last protomotive twin plug 993 beast I have seen had dual Crane CDI units on it. The motor is out of the car becaused it was wrecked. I drool over it often.

I love the technical aspect of this thread!!!!!

Red rooster

Geoffrey,
I am sorry if it came across that I doubted what you were saying !!

What I was saying was that a few simple sums on ignition coil energy storage levels and the time required to achieve them didnt explain what you are seeing.

How much has the boost pressure got to be raised to give ignition misfire ? I am interested, because this is suggesting that even at standard boost there is not a lot of spare ignition energy !!
With a handle on this , maybe a different coil characteristic ( inductance-resistance ) would be better .

I agree that CDi solves pretty well any rpm issue but it does have the downside of very short spark duration which can be a problem for some motors !

This is like any search for perfection ! always nearly there !!!

All the best

Geoff

Jean

Geoffrey, I cannot follow the technical aspects of your statements but I will give it a try.
I am running indeed the stock coils but I should have specified not the stock spark plugs, and it does make a huge difference. The engine dyno tests showed the engine peaking at 600HP with the stock spark plugs no matter what boost it was running. After the spark plug change, the power immediately went up and did not plateau again until 1.14Bars, there will be a threshold somewhere later, not sure where though. In the meantime, this engine was producing outstanding HP per absolute bar, meaning ignition was not only running well, but producing horsepower, as shown also on my dyno charts.

K24, you are perfectly right, and initially we were going to go with the Crane Hi-6 with dual coils or dual MSD 6a's, but after seeing how this engine behaved with this semi-stock setup and not even custom injector drivers, and bearing in mind the paramount need to keep it simple due to the lack of local support that I have here, there was no need for it. It can be upgraded if need in the future with the high end stuff.

Geoffrey is right when he says that the engine can be running smooth however not producing power, and this is what was seen on the dyno, the HP was limited with stock plugs, and no sign of cylinders dropping out etc.. That's the magic of a turbo engine, on a weaker C2 or C4 N/A engine you would certainly feel an issue, especially with the lousy triple electrode FR5DTC that they run apparently.
In my case power and smoothness are all there it seems?

JJayB

Kevin
Thanks for clairifying that is not going to be a speedway racer with 80% time at 8500. As to my efficiency range. You are correct I'm at the end of this project and not looking to engineer the next level. I'll let you do that. I have found that there is little on the motorsport scene at least at the club level that is a match for the power of the 3.8 in its present configuration. I'm sure somebodys friend has a relative that has something faster but we have yet to meet.

Geof
The Calif. desert can be cruel with 110 f temps. This is usually when we see elevated inlet temp. By using a progrmable ecu, I switch to a lower boost, timing etc. program to control the inlet temps.

IrocMan

Damned,
There's no week I don't have a dream about it.
It's the only thing I miss to build my engine. I'm thinking about machining one for my twin turbo, did you heard about someone who already tried (succeed?) it ?

Kevin

Simon, M42Racer has/had 2 or 3 top/center fan systems.. The cost is $$$

Rickard 993 Turbo

Yes a guy here in swden has made a kit with CF top fan