Dyno Video of Mike Simard's 427 c.i. 928 engine
07-31-2009, 06:07 PM
#16
Rennlist Member
Sounds like with you, there would be no need for discussion 
interesting that you got so little torque peak with the restrictors. But, in the end, it plays to the advantage of using the rules. lower torque than HP . nice! (easier on the tranmission too)
sounds like you are right there. in fact, you are a little above my set for power and torque now. might be a good race. Im near 2900lbs with driver as I come off the race course. (372rwhp/402rwt)
Have fun and let us know how it does!
btw, how did you get the car so light? thats lighter or near the same as andersons car!
Mark
interesting that you got so little torque peak with the restrictors. But, in the end, it plays to the advantage of using the rules. lower torque than HP . nice! (easier on the tranmission too)
sounds like you are right there. in fact, you are a little above my set for power and torque now. might be a good race. Im near 2900lbs with driver as I come off the race course. (372rwhp/402rwt)
Have fun and let us know how it does!
btw, how did you get the car so light? thats lighter or near the same as andersons car!
Mark
It's a pleasure to enter a torque discussion with you Mark!
Here are the rules with the power/weight table:
http://www.nasaproracing.com/rules/GTS-Challenge.pdf
The restrictors put me at 442 hp and 402 tq. That's 422 for the formula.
My race weight is 2780 (me, the car and some fuel)
That's a 6.59 ratio which is GTS5. It's also just enough to allow slicks which is nice because I can get free used slicks!
Here are the rules with the power/weight table:
http://www.nasaproracing.com/rules/GTS-Challenge.pdf
The restrictors put me at 442 hp and 402 tq. That's 422 for the formula.
My race weight is 2780 (me, the car and some fuel)
That's a 6.59 ratio which is GTS5. It's also just enough to allow slicks which is nice because I can get free used slicks!
07-31-2009, 06:29 PM
#17
Nordschleife Master
07-31-2009, 08:20 PM
#18
Drifting
omg
omg!!!I just saw this thread. You are quite the talented engine builder...I take it this engine and racing is for the fun and the engineering machining is the business...I want to be you in my next life!
andy
andy
07-31-2009, 08:57 PM
#20
Owns the Streets
Needs Camber
Lifetime Rennlist
Member
Needs Camber
Lifetime Rennlist
Member
Thread Starter
08-02-2009, 11:12 PM
#22
Three Wheelin'
Ice', I posted the dyno chart and some pics at Pelican. I'll get the restricted one up.
The restrictors are a pair of 1.5" bore donuts inside the airbox inlets.
With them the power peaks at about 6500 and starts to trail off gradually. That may be advantageous over a smaller unrestriced engine or not. It is nice to be able to get a precise power number that way. If it's less likely to detonate and blow up that might also be nice but this engine is still too much for the car.
MK, the car started as a bare shell with nothing going back on it that didn't need to be there. That's the way to get really light. No orginal wiring, heater, side windows, wipers etc. This car is about as light as one can be and not fall apart or leave you missing something
The restrictors are a pair of 1.5" bore donuts inside the airbox inlets.
With them the power peaks at about 6500 and starts to trail off gradually. That may be advantageous over a smaller unrestriced engine or not. It is nice to be able to get a precise power number that way. If it's less likely to detonate and blow up that might also be nice but this engine is still too much for the car.
MK, the car started as a bare shell with nothing going back on it that didn't need to be there. That's the way to get really light. No orginal wiring, heater, side windows, wipers etc. This car is about as light as one can be and not fall apart or leave you missing something
08-03-2009, 03:17 AM
#24
Rennlist Member
08-03-2009, 03:51 AM
#26
Nordschleife Master
I had a valve break at the keeper groove which was unusual. It was a TRW 968 replacement which is common from all sources incuding from Porsche in Germany. I'm sure that the TRW plant is in China for my valve by the markings and finish. The 3 groove design isn't optimal for heavy use because it doesn't clamp on the stem but is loose to allow rotation. With 80s vintage German Porsche parts that's no problem but my TRW valve was made with looser tolerances and the 3 grooves were just slightly looser than originals. That allowed the retainer to rock quite noticably which will break a valve at the keeper groove. That leaves the only reliable valves as custom Ferreas or Supertechs.
Here's what I am planning to do, perhaps you can give me some pointers.
I am planning to use the stock 928 valves. I've collected a bunch of used valves, I probably have about 100 of each at this point. We'll pick a consistent set among those. This is for a turbo engine so the 37mm and 33mm valves are enough by my estimation. The intakes are magnetic steel and the exhaust have non-magnetic lower part and magnetic upper part. The stock exhaust valves are pretty thick and I haven't seen or heard of a burned one. Also, the weld surface on the exhaust valves should hold well as long as the valve guides are tight. This leaves the tripple groove tip as the weak spot.
On the groove, the plan is as follows. In stock configuration, the valves are loose in the keepers and the keepers butt, which allows the valves to rotate in the seat. This will presumably make the seat and valve contact surface wear evenly and seal longer. My plan is to take the keepers and grind/sand/whatnot them down a bit until the keepers no longer butt. Instead, the collet mechanism will hold/squeeze the valve the same way as with the single groove racing valves. By my estimation, this will hold the valve in a way that it can't bang its grooves up and down against the keeper.
What do you think?
08-03-2009, 10:13 AM
#30
Rennlist Member
