HIGHWAYMAN: Bringing the Devore 928 back from the dead
11-22-2017, 10:42 AM
#841
Developer
That's a good chart, Eric, and useful. Can you remove the extrude-honed manifold from it? It was a one-of (and it has now been sold) so I don't think we will see that again. But I'd like to see these two - the stock and the Hi-rise 654 on one page like this.
To answer the question about why we stopped at 6700 rpm: I built and balanced the motor to go to 7,000 rpm, and the dyno operator was cleared to take it there if he saw a reason. But if you look at the torque numbers, the torque had been fairly consistent from its peak at 5400 all the way to about 6200 rpm (nice!), and that is the range the race car driver will be instructed to live in. Above that, the torque is falling off too fast, and he should grab another gear. So, as long as the torque was falling off, there was no reason to go higher. Bob (the guy at the Dyno controls) asked me if I wanted to do another pull and carry it to 7, and I said no.
To answer the question about why we stopped at 6700 rpm: I built and balanced the motor to go to 7,000 rpm, and the dyno operator was cleared to take it there if he saw a reason. But if you look at the torque numbers, the torque had been fairly consistent from its peak at 5400 all the way to about 6200 rpm (nice!), and that is the range the race car driver will be instructed to live in. Above that, the torque is falling off too fast, and he should grab another gear. So, as long as the torque was falling off, there was no reason to go higher. Bob (the guy at the Dyno controls) asked me if I wanted to do another pull and carry it to 7, and I said no.
11-22-2017, 10:54 AM
#842
Nordschleife Master
To answer the question about why we stopped at 6700 rpm: I built and balanced the motor to go to 7,000 rpm, and the dyno operator was cleared to take it there if he saw a reason. But if you look at the torque numbers, the torque had been fairly consistent from its peak at 5400 all the way to about 6200 rpm (nice!), and that is the range the race car driver will be instructed to live in. Above that, the torque is falling off too fast, and he should grab another gear. So, as long as the torque was falling off, there was no reason to go higher. Bob (the guy at the Dyno controls) asked me if I wanted to do another pull and carry it to 7, and I said no.
11-22-2017, 11:42 AM
#843
Drifting
ptuomov is correct in his assessment regarding engine output and shift points. Carl, sometimes saying less is most times saying more.
Considering the intended use of the engine, since it won't be used for championship points or prize money, there's no need to wring it out to max RPM.
As such, choosing a shift-point of 6,700 RPM, the engine should last virtually forever.
Considering the intended use of the engine, since it won't be used for championship points or prize money, there's no need to wring it out to max RPM.
As such, choosing a shift-point of 6,700 RPM, the engine should last virtually forever.
11-22-2017, 11:58 AM
#844
Supercharged
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ptuomov is correct in his assessment regarding engine output and shift points. Carl, sometimes saying less is most times saying more.
Considering the intended use of the engine, since it won't be used for championship points or prize money, there's no need to wring it out to max RPM.
As such, choosing a shift-point of 6,700 RPM, the engine should last virtually forever.
Considering the intended use of the engine, since it won't be used for championship points or prize money, there's no need to wring it out to max RPM.
As such, choosing a shift-point of 6,700 RPM, the engine should last virtually forever.
11-22-2017, 12:00 PM
#845
Developer
This could quickly deteriorate into a bar-stool argument about what wins races, torque or HP. (A bar-stool argument is one that has no firm answer, and will not end until the beer runs out). In my readings, I have found authors who argue both sides. I was instructed that it is torque that accelerates a car out of the corners, and the torque curve of the motor tells us where the shift points should be. But, to each is own.
Here is another item for your rpm consideration. The puke-point on this motor is 6700 rpm. Although fitted with a crankcase scraper, oil diverter for drain-back from the heads, and a good windage tray - you still cannot take the 928 out of the 928... that left head will fill up with oil faster than it can drain back and when that happens, the vent in the left cam cover will puke. Much has been written about the 928 puking liquid oil on many threads - this "anomoly" is well known. I say "anomoly" because the guys at the engine dyno will tell you a LOT of V8's do this, we are not alone. Anyway, on the dyno, we found that the puke-point for this motor was 6700 rpm. Only the left head pushed oil. In a race car, the cam cover vents would be vented to an oil separator or a catch tank , and returned into the motor from there. At the dyno we just let it burp on to the floor.
So... another reason to stay under 6500 rpm... let the oil in the heads drain back, don't starve the sump for oil, and have the race motor last a long time.
Exactly.
Here is another item for your rpm consideration. The puke-point on this motor is 6700 rpm. Although fitted with a crankcase scraper, oil diverter for drain-back from the heads, and a good windage tray - you still cannot take the 928 out of the 928... that left head will fill up with oil faster than it can drain back and when that happens, the vent in the left cam cover will puke. Much has been written about the 928 puking liquid oil on many threads - this "anomoly" is well known. I say "anomoly" because the guys at the engine dyno will tell you a LOT of V8's do this, we are not alone. Anyway, on the dyno, we found that the puke-point for this motor was 6700 rpm. Only the left head pushed oil. In a race car, the cam cover vents would be vented to an oil separator or a catch tank , and returned into the motor from there. At the dyno we just let it burp on to the floor.
So... another reason to stay under 6500 rpm... let the oil in the heads drain back, don't starve the sump for oil, and have the race motor last a long time.
As such, choosing a shift-point of 6,700 RPM, the engine should last virtually forever.
Last edited by Carl Fausett; 11-22-2017 at 12:18 PM.
11-22-2017, 12:03 PM
#846
Developer
Until you come up against a Viper ACR, GT3RS, etc that has more power than you and you're on the front straight at Road America or the back straight at VIR. Then you will wish that you had a higher Rev limit to get all the power...
11-22-2017, 12:24 PM
#847
Drifting
Carl, if you could post the real graphs from the runs, perhaps that would motivate Erik to take down his manually generated graphs he so kindly produced for all the 6.54 admirers/ooglers. 
11-22-2017, 12:24 PM
#848
Banned
Thread Starter
Guys, remember this was done on an engine dyno as Carl stated. When I get the car together, and all systems are working (breathers, accusump, etc.) then I will break it in a little with some autocrosses and get time on the motor.
Also, keep in mind that this setup has the crappy dyno headers - I believe that the custom MSDS headers will give it a little more power as well.
I will probably end up putting the whole setup on a chassis dyno locally after it's had some time on it to dial it in and see where we are at. Yeah, I know there is a wide variance on chassis dynos and it will never again be an apples to apples comparison, but we can still get an idea of what it puts out in the real world with all systems operational as it would be in the car.
If you follow the graph that Erik graciously made, 300 more RPM buys you like 15 hp. or thereabouts if I am reading it right.
11-22-2017, 12:26 PM
#849
Banned
Thread Starter
A GT3RS has significantly less power than this car and is close to 800 pounds heavier......my car makes as much power at the wheel as an RS makes at the crank.....
11-22-2017, 01:01 PM
#850
Developer
A GT3RS has significantly less power than this car and is close to 800 pounds heavier......my car makes as much power at the wheel as an RS makes at the crank.....
11-22-2017, 01:40 PM
#851
Nordschleife Master
This could quickly deteriorate into a bar-stool argument about what wins races, torque or HP. (A bar-stool argument is one that has no firm answer, and will not end until the beer runs out). In my readings, I have found authors who argue both sides. I was instructed that it is torque that accelerates a car out of the corners, and the torque curve of the motor tells us where the shift points should be. But, to each is own.
Here is another item for your rpm consideration. The puke-point on this motor is 6700 rpm. Although fitted with a crankcase scraper, oil diverter for drain-back from the heads, and a good windage tray - you still cannot take the 928 out of the 928... that left head will fill up with oil faster than it can drain back and when that happens, the vent in the left cam cover will puke. Much has been written about the 928 puking liquid oil on many threads - this "anomoly" is well known. I say "anomoly" because the guys at the engine dyno will tell you a LOT of V8's do this, we are not alone. Anyway, on the dyno, we found that the puke-point for this motor was 6700 rpm. Only the left head pushed oil. In a race car, the cam cover vents would be vented to an oil separator or a catch tank , and returned into the motor from there. At the dyno we just let it burp on to the floor. So... another reason to stay under 6500 rpm... let the oil in the heads drain back, don't starve the sump for oil, and have the race motor last a long time.
If the redline is going to be 6500rpm or 6700rpm, my guess from the dyno curves is that one could get more average power between shift points by reducing the intake runner cross-sectional area. If you're making more of these manifolds, I'd make the next version intended for a 600hp engine and 6500rpm redline with slightly smaller runners IDs.
Out of curiosity, what are the camshaft specs on this engine?
11-22-2017, 03:42 PM
#853
Banned
Thread Starter
This is the first real reproduceable manifold that you can just slap on an engine and achieve big power with. Unlike the ITB setup that made a little more, the tuning of this setup is stupid simple and at the risk of repeating myself, one can easily reproduce the product. And it will last forever, no delamination or deterioration like the CF ones out there.
11-22-2017, 04:05 PM
#854
The Parts Whisperer
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11-22-2017, 04:07 PM
#855
Banned
Thread Starter
Yeah, I think the ITB setup was 630 or 640, don't remember exactly. Maybe someone else can dig up the number.
But my point is ITBs are finicky to setup correctly, I have done them on another (non 928) and they are almost not worth the hassle.
But my point is ITBs are finicky to setup correctly, I have done them on another (non 928) and they are almost not worth the hassle.