Do these pictures need captions? (32V Intake Manifold Study - HP)
10-27-2013, 10:14 PM
#211
Rennlist Member
If it helps anyone, the port in the head at the flange has a cross-sectional area of 1868mm^2 which is the equivalent of a ~48.75mm or 1.91" tube. So, perhaps a larger runner would not be that beneficial?
That is the port in the head, the manifold itself would have a bit less area if the bung was located in the stock location. In the flange I was working on, the area was 1688mm^2, so there could be another advantage to the higher injector bung location you chose.
Not trying to threadjack, just had the figures handy if they helped this discussion.
That is the port in the head, the manifold itself would have a bit less area if the bung was located in the stock location. In the flange I was working on, the area was 1688mm^2, so there could be another advantage to the higher injector bung location you chose.
Not trying to threadjack, just had the figures handy if they helped this discussion.
10-27-2013, 11:15 PM
#212
Former Sponsor
Thread Starter
If it helps anyone, the port in the head at the flange has a cross-sectional area of 1868mm^2 which is the equivalent of a ~48.75mm or 1.91" tube. So, perhaps a larger runner would not be that beneficial?
That is the port in the head, the manifold itself would have a bit less area if the bung was located in the stock location. In the flange I was working on, the area was 1688mm^2, so there could be another advantage to the higher injector bung location you chose.
Not trying to threadjack, just had the figures handy if they helped this discussion.
That is the port in the head, the manifold itself would have a bit less area if the bung was located in the stock location. In the flange I was working on, the area was 1688mm^2, so there could be another advantage to the higher injector bung location you chose.
Not trying to threadjack, just had the figures handy if they helped this discussion.
10-29-2013, 12:55 PM
#213
Rennlist Member
I once read an article by a famous engine builder [cannot remember the name] who reckoned that a measure of a good street motor is the area under the curve bounded by 80% of peak torque. Rob's motor has 80% at max rpm and as I can infer, probably 80% at or close to 2k rpm.
That is one stonking motor and it would be interesting to see some of the more notable 928 motors on the same dyno. Just as interesting is the way top end power has that broad peak- seems to last forever. Sort of looks like a twin screw output without the rubber band -
Very impressive concept but then I am not at all surprised.
Once the build parameters have been resolved would it be possible to make some tapered inserts [with smaller internal diameter] to tune for 5 litre & 5.4 litre variants assuming you can get the fuel injected OK?
Regards
Fred
That is one stonking motor and it would be interesting to see some of the more notable 928 motors on the same dyno. Just as interesting is the way top end power has that broad peak- seems to last forever. Sort of looks like a twin screw output without the rubber band -
Very impressive concept but then I am not at all surprised.
Once the build parameters have been resolved would it be possible to make some tapered inserts [with smaller internal diameter] to tune for 5 litre & 5.4 litre variants assuming you can get the fuel injected OK?
Regards
Fred
10-29-2013, 11:47 PM
#214
Rennlist Member
I once read an article by a famous engine builder [cannot remember the name] who reckoned that a measure of a good street motor is the area under the curve bounded by 80% of peak torque. Rob's motor has 80% at max rpm and as I can infer, probably 80% at or close to 2k rpm.
That is one stonking motor and it would be interesting to see some of the more notable 928 motors on the same dyno. Just as interesting is the way top end power has that broad peak- seems to last forever. Sort of looks like a twin screw output without the rubber band -
Very impressive concept but then I am not at all surprised.
Once the build parameters have been resolved would it be possible to make some tapered inserts [with smaller internal diameter] to tune for 5 litre & 5.4 litre variants assuming you can get the fuel injected OK?
Regards
Fred
That is one stonking motor and it would be interesting to see some of the more notable 928 motors on the same dyno. Just as interesting is the way top end power has that broad peak- seems to last forever. Sort of looks like a twin screw output without the rubber band -
Very impressive concept but then I am not at all surprised.
Once the build parameters have been resolved would it be possible to make some tapered inserts [with smaller internal diameter] to tune for 5 litre & 5.4 litre variants assuming you can get the fuel injected OK?
Regards
Fred
We happened to be in Anaheim, and Greg happened to have Rob's car in the shop with his prototype intake, so they swapped it onto our GT and we went for a drive. This was just a science experiment, to find out what an intake designed for a 6.5L motor would do with a 5.0L with good cams and exhaust.
Bottom line, +39 hp from intake swap alone, and +23 ft-lb torque, with a quickie Sharktune.
A couple of things are interesting: The first is that this shows a strong resonance effect. It could be tuning, we didn't spend a lot of time-- but the waves in the torque curve look more like resonances, and to a much greater degree than with Rob's motor (green curves). Larger tubes (relative to engine displacement) mean lower velocity, but also less resistance-- hence stronger resonance???
We lost the lower resonance of the stock intake (no flappy), in fact there is a divot there. The timing is relatively flat from there up (roughly 20-deg advance), maybe fiddling with timing and adjusting the RPM scale would help fill that in-- but that might mess up the science.
The other interesting thing is that the engine did not need- and would not tolerate- as much advance as with the stock intake. With the stock intake this engine (GT with cams and headers) wants around 22-23 deg advance at the top end. But with the prototype intake we dyno'ed with 18 deg and that was still too much-- the EZK took out a bunch above 5500 rpm. I don't know what that means-- one theory is that a good intake packs more charge into the cylinder, which means higher pressures and faster burning, which means less advance is needed (or tolerated).
This dyno run was on a Dynojet at Superior Automotive in Anaheim, good folks-- old-school and very experienced. But once again this underscores the fact that all dyno's are not created equal-- we were down a little over 20hp here compared to an identical Dynojet near us (Marysville Speed), equally old-schooled and experienced. Different dyno, different state, different gas, different results. Not a problem, we just did the before/after on the same dyno, same operator, same fuel.
Run-2 (blue) was our "before", GT with headers and 2.5" exhaust, bigger-than-GT cams, JDS Alpha (mafless) system. Run-5 (red) was the "after" with the intake swapped for GB's prototype, and run-17 (green) was the "after" for Rob's stroker (GB headers and exhaust, JDS Alpha, and the same prototype intake).
Interesting stuff, this.
Cheers, Jim
10-30-2013, 12:08 AM
#215
Race Director
Interesting how high the torque peak is on the GT motor.... I would imagine that the stock intake GT feels stronger down low, just to get destroyed by the intake motor in the higher RPM....wow..it also shows how much difference 1.4L makes....small motor torque peak is 5250rpm vs neary flat 4200-5000 for the big motor....HP peaks are similar Robs is falling past 6000 and yours could go even higher than where it was shut down.....
Doing the BMEP calculations between the two is interesting....using a 10% drivetrain loss puts your GT motor at about 373ftlbs at torque peak or 186.25psi vs Robs 516ftlbs at 199psi, granted much lower in the rpm too...I would guess Rob's engine could have an even bigger intake to maximze top end power, but that was never the goal for a street car anyway...
Great data......glad you guys did the testing!!!
Doing the BMEP calculations between the two is interesting....using a 10% drivetrain loss puts your GT motor at about 373ftlbs at torque peak or 186.25psi vs Robs 516ftlbs at 199psi, granted much lower in the rpm too...I would guess Rob's engine could have an even bigger intake to maximze top end power, but that was never the goal for a street car anyway...
Great data......glad you guys did the testing!!!
10-30-2013, 01:55 AM
#216
Drifting
How peaky are the cams in the stroker? Looks like the torque curves for the GT vs stroker show the GT with a similar curve but shifted to the R) - and lower of course! I bet the GT is a different animal to drive with the intake.
10-30-2013, 02:48 AM
#217
Archive Gatekeeper
Rennlist Member
Rennlist Member
Not terribly peaky- The cams in my stroker are reground GT cams, .420 intake and .380 exhaust. Duration is 263 and 256 at 1mm lift. So not too much lift but craploads of duration. The cams in Jim's engine are (I think) Colin's Medium, or Stage II cams, .424 and .424 (?) Dunno Jim's duration specs
10-30-2013, 03:03 AM
#218
Archive Gatekeeper
Rennlist Member
Rennlist Member
FWIW, here's the install on Jim's 90GT. Looks totally different on a 5L motor, no? 
10-30-2013, 06:05 AM
#219
Race Car
Not terribly peaky- The cams in my stroker are reground GT cams, .420 intake and .380 exhaust. Duration is 263 and 256 at 1mm lift. So not too much lift but craploads of duration. The cams in Jim's engine are (I think) Colin's Medium, or Stage II cams, .424 and .424 (?) Dunno Jim's duration specs
How is the idle and the vacuum accessories, any effect vs. stock?
10-30-2013, 10:48 AM
#224
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Very nice intake setup there. One question arisen up after looking Jims GT and Robs stroker dyno graphs,
why GT is able to produce power even after 6000rpm, but stroker stops little before 6000rpm? Perhaps the intake is still slightly too small for
stroker to allow breathing after 6000rpm. Could also be that the plenum size, intake tube lenght and diameter have been designed this way,
no need to spin engine to death if it happens to have enough displacement
Decreasing the ignition advance in case of volumetric efficiency(charge) is increasing is actually good thing.
When the piston is coming up and starts compressing the AF-mixture it needs to work harder if ignition advance is set to higher value
since the fast burning process increases rapidly the pressure in the cylinder.
It's better to get as high as possible charge to cylinder and start burning process later to get more power.
By this way the piston will use it's moving energy by compressing the large amount of charge and not fighting against rapidly increasing
pressure generated by early ignition.
Greg, keep going with the intake development. I like the idea, it's nice and compact package.
Just for general interest, lot's of intake talk here: http://www.theturboforums.com/thread...anifold-design
why GT is able to produce power even after 6000rpm, but stroker stops little before 6000rpm? Perhaps the intake is still slightly too small for
stroker to allow breathing after 6000rpm. Could also be that the plenum size, intake tube lenght and diameter have been designed this way,
no need to spin engine to death if it happens to have enough displacement
Decreasing the ignition advance in case of volumetric efficiency(charge) is increasing is actually good thing.
When the piston is coming up and starts compressing the AF-mixture it needs to work harder if ignition advance is set to higher value
since the fast burning process increases rapidly the pressure in the cylinder.
It's better to get as high as possible charge to cylinder and start burning process later to get more power.
By this way the piston will use it's moving energy by compressing the large amount of charge and not fighting against rapidly increasing
pressure generated by early ignition.
Greg, keep going with the intake development. I like the idea, it's nice and compact package.
Just for general interest, lot's of intake talk here: http://www.theturboforums.com/thread...anifold-design
10-30-2013, 11:08 AM
#225
Rennlist Member
Interesting comments, Fred -- Thanks! I've always believed that a broad torque curve that didn't quit was a key component of an enjoyable car.
We happened to be in Anaheim, and Greg happened to have Rob's car in the shop with his prototype intake, so they swapped it onto our GT and we went for a drive. This was just a science experiment, to find out what an intake designed for a 6.5L motor would do with a 5.0L with good cams and exhaust.
Bottom line, +39 hp from intake swap alone, and +23 ft-lb torque, with a quickie Sharktune.
A couple of things are interesting: The first is that this shows a strong resonance effect. It could be tuning, we didn't spend a lot of time-- but the waves in the torque curve look more like resonances, and to a much greater degree than with Rob's motor (green curves). Larger tubes (relative to engine displacement) mean lower velocity, but also less resistance-- hence stronger resonance???
We lost the lower resonance of the stock intake (no flappy), in fact there is a divot there. The timing is relatively flat from there up (roughly 20-deg advance), maybe fiddling with timing and adjusting the RPM scale would help fill that in-- but that might mess up the science.
The other interesting thing is that the engine did not need- and would not tolerate- as much advance as with the stock intake. With the stock intake this engine (GT with cams and headers) wants around 22-23 deg advance at the top end. But with the prototype intake we dyno'ed with 18 deg and that was still too much-- the EZK took out a bunch above 5500 rpm. I don't know what that means-- one theory is that a good intake packs more charge into the cylinder, which means higher pressures and faster burning, which means less advance is needed (or tolerated).
This dyno run was on a Dynojet at Superior Automotive in Anaheim, good folks-- old-school and very experienced. But once again this underscores the fact that all dyno's are not created equal-- we were down a little over 20hp here compared to an identical Dynojet near us (Marysville Speed), equally old-schooled and experienced. Different dyno, different state, different gas, different results. Not a problem, we just did the before/after on the same dyno, same operator, same fuel.
Run-2 (blue) was our "before", GT with headers and 2.5" exhaust, bigger-than-GT cams, JDS Alpha (mafless) system. Run-5 (red) was the "after" with the intake swapped for GB's prototype, and run-17 (green) was the "after" for Rob's stroker (GB headers and exhaust, JDS Alpha, and the same prototype intake).
Attachment 774152
Interesting stuff, this.
Cheers, Jim
We happened to be in Anaheim, and Greg happened to have Rob's car in the shop with his prototype intake, so they swapped it onto our GT and we went for a drive. This was just a science experiment, to find out what an intake designed for a 6.5L motor would do with a 5.0L with good cams and exhaust.
Bottom line, +39 hp from intake swap alone, and +23 ft-lb torque, with a quickie Sharktune.
A couple of things are interesting: The first is that this shows a strong resonance effect. It could be tuning, we didn't spend a lot of time-- but the waves in the torque curve look more like resonances, and to a much greater degree than with Rob's motor (green curves). Larger tubes (relative to engine displacement) mean lower velocity, but also less resistance-- hence stronger resonance???
We lost the lower resonance of the stock intake (no flappy), in fact there is a divot there. The timing is relatively flat from there up (roughly 20-deg advance), maybe fiddling with timing and adjusting the RPM scale would help fill that in-- but that might mess up the science.
The other interesting thing is that the engine did not need- and would not tolerate- as much advance as with the stock intake. With the stock intake this engine (GT with cams and headers) wants around 22-23 deg advance at the top end. But with the prototype intake we dyno'ed with 18 deg and that was still too much-- the EZK took out a bunch above 5500 rpm. I don't know what that means-- one theory is that a good intake packs more charge into the cylinder, which means higher pressures and faster burning, which means less advance is needed (or tolerated).
This dyno run was on a Dynojet at Superior Automotive in Anaheim, good folks-- old-school and very experienced. But once again this underscores the fact that all dyno's are not created equal-- we were down a little over 20hp here compared to an identical Dynojet near us (Marysville Speed), equally old-schooled and experienced. Different dyno, different state, different gas, different results. Not a problem, we just did the before/after on the same dyno, same operator, same fuel.
Run-2 (blue) was our "before", GT with headers and 2.5" exhaust, bigger-than-GT cams, JDS Alpha (mafless) system. Run-5 (red) was the "after" with the intake swapped for GB's prototype, and run-17 (green) was the "after" for Rob's stroker (GB headers and exhaust, JDS Alpha, and the same prototype intake).
Attachment 774152
Interesting stuff, this.
Cheers, Jim
That seems pretty good to me! When can we put one on a 5.4L!