DonE

Agreed.

Unfortunately, showing a dyno of 500 hp doesn't mean much anymore given tuners who enter BS correction factors. I worked very hard and spent a lot of money to produce a CIS car with 412 rwhp, verified using 2 different dynos. I think 400 - 425 rwhp is most likely a max number for a CIS car.

onboost

I understand this to be true as well and that has been my belief.
However, I also understand that Porsche, and many others were getting 500 hp out of these engines in the late 70s and through the 80s etc.. on CIS..

If that's the biggest drawback to getting these kind of numbers then obviously somebody somewhere was doing something to get some fuel delievery... supposedly DP, Andial, Powerhaus and others were getting 500 hp out of no-EFI motors.. or at least that's what they were selling!

Any thoughts?

DonE

You're talking about factory race cars now.

If I would have had a big dollar budget, I bet I could have reached 500 hp with my CIS. It would have only lasted 500 miles before a rebuild, but with custom valves, valve train, rods, rod bolts, head studs, fire rings, pistons, turbo, intake, exhaust, intercooler, etc, etc, I bet it would have been possible.

PorschePhD

The 935 didn't use CIS nor did a majority of the big HP cars. They used hybrids of several system and most were based on MFI. To increase flow all one did was change the pump curving. My point it Porsche never made HUGE power through a fuel head.


As Don has mentioned there is no way Twin plug adds anything HP wise. If it does it is from a more efficient burn and you can gain a little TQ (like under 10 overall) It purpose has never been one to increase HP rather make a complete burn and be able to back off the timing to achieve the same thing yet allow a little more compression. Instead of timing needing to be so far advanced to make sure the flame is complete in the chamber from the spark plug to the other side of the chamber (remember CIS pistons create a swirl effect as the flame iginites) you run less timing because it flashed both halves of the piston. So complete burn is done with less timing. The real gains come from the ignition systems usually used with the TP and the ability to change the curve to be a little more aggressive down low and back off in the mid and top range based on MAP retard.

schnele

Stephen is on the money, the 935 used the crude Zytec system for fuel management.

DonE

Crude?

schnele

Zytec is very difficult for end user interface, if you have a race team to tune it for WOT only then it should be fine.

JBL930

Forgive my ignorance, to go twin plug with CIS would you need a 12 point dizzy like this?



Or is there another way of doing it?

PorschePhD

No there are several systems, one that uses another cap and rotor off of the cam, then many systems that are direct fire and digital. They use a sensor off of the crank, flywheel etc.

A.Wayne

my experiences are different in that Twin plug cars do show a difference even at idle when you disconnect one set of the ignition system.

yes , you can use multiple coils or wastespark coils or twin distributors ala 964..

Daley88930

i am in total agreement with Chuck. Mine has not been on the Dyno but it scares the Hell out of me. Anyway, check out this guy--I have talked to him several times and he is for real. SPEZIALMOTORER
Good Luck