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For drag racing I think you'd want to shorten the runners up and nail the first reversion right around peak power. The second harmonic is much weaker than the first isn't it?
The holley sniper barely has any runner length. You won't be losing any tuned point with the sniper - it's performance is purely from huge flow and velocity over the longer runner stuff at high rpm.
For drag racing I think you'd want to shorten the runners up and nail the first reversion right around peak power. The second harmonic is much weaker than the first isn't it?
The holley sniper barely has any runner length. You won't be losing any tuned point with the sniper - it's performance is purely from huge flow and velocity over the longer runner stuff at high rpm.
You are right about the harmonics strength. They weaken as the number of reversions increase. However, on the Hurricane you hit the 3rd reversion at about 5700 RPM, while a MSD hits the 3rd reversion around 6500 RPM. At 6500 RPM the Hurricane is in a slump in between the 2nd and the 3rd reversion, meaning the pressure waves just reach the inlet of the runner instead of being at the opposite side at the intake valve. Now if you rev higher, the 2nd reversion will exactly hit the intake valve.
The shorter runners are also only good when the timing is right. So comparing single throttle body intakes, hitting the 3rd reversion just right will yield more power than being in between the 2nd and 3rd reversion. However, if you are able to hit the 2nd reversion at the same RPM as the 3rd reversion, you will gain LOTS of power over the 3rd reversion intake.
Hitting the 1st reversion between 5500 - 8000 RPM would actually require a very long runner. The MOPAR 'long ram' was one of these intake manifolds that tried to hit the first reversion. In theory it is good if you have enough space in the engine bay to make such a long runner, with it still being aerodynamically an acceptable design. A drawback of these runners is the increase in the friction losses on the long walls. The 1st reversion runner is twice the length of the 2nd reversion runner. The 3rd reversion runner is 2/3 in length of the 2nd reversion, so the increase in friction is not as great there anymore. In other words the gains from the increased energy of the 1st reversion vs. the 2nd have to outweigh the losses due to friction and 'bad' runner design due to space issues in the engine bay.
robz and GARY2004Z06 on the Corvetteforum had a very similar setup to yours with a 388 LS7 revving to 8150 RPM. If I'm not mistaking they made the fastest NA Corvette with a regular H pattern shifter on a quarter mile. They used the Harrop Hurricane with great success due to the RPM of the engine. You might wanna contact them about dyno charts. I know there are a few videos on youtube with the car.
robz and GARY2004Z06 on the Corvetteforum had a very similar setup to yours with a 388 LS7 revving to 8150 RPM. If I'm not mistaking they made the fastest NA Corvette with a regular H pattern shifter on a quarter mile. They used the Harrop Hurricane with great success due to the RPM of the engine. You might wanna contact them about dyno charts. I know there are a few videos on youtube with the car.
ok yeah I know the car. Rob still pops in here from time to time
ok yeah I know the car. Rob still pops in here from time to time
I've been tempted to change course with my short-runner Plazmaman (above) for the Hurricane for my street build with a beefed-up L680. The only hesitation has been with fitment. Regarding performance, it seems like a no-brainer in a daily driver roll. I would appreciate your opinion and that of others'.
I've been tempted to change course with my short-runner Plazmaman (above) for the Hurricane for my street build with a beefed-up L680. The only hesitation has been with fitment. Regarding performance, it seems like a no-brainer in a daily driver roll. I would appreciate your opinion and that of others'.
harrop sent me the dimensions and I think it’ll just fit in an fbody without cutting but will take work. Not a bolt on deal at al but if you’re not afraid to think outside the box it’ll be fine. As far as streetabiility and performance I don’t think you can beat ITB’s especially with Big cams since they eliminate port reversion at low rpm and idle.
harrop sent me the dimensions and I think it’ll just fit in an fbody without cutting but will take work. Not a bolt on deal at al but if you’re not afraid to think outside the box it’ll be fine. As far as streetabiility and performance I don’t think you can beat ITB’s especially with Big cams since they eliminate port reversion at low rpm and idle.
I failed to point out that my Chevy SS sedan is of the Zeta platform 2014-2017. Harrop wasn't sure about the fit-up, as the difference between the right-hand drive engine bay (Aussie) is different, and they don't any reference to a left-hand drive (USA) configuration. I think the AC hard lines on the Chevy SS version is a potential issue. If I proceed, it's likely I would be the first to try it on this particular body type.
Last edited by Saber-1; 10-10-2018 at 11:30 AM.
Reason: more to say...
So here are some preliminary dyno plots. We gained about 10-20 hp nearly everywhere, depending on RPM. However, compared to my old setup, which was in one of the images posted above, we lost 20-40 hp depending on RPM.
I did some CFD to resolve this issue, as the airboxes are actually better than the old design. It turns out that the hoses have 25% momentum (mass flow) loss compared to a straight pipe of equal diameter and length.
Therefore I will make a carbon filter box, similar to the old design and we should be back on the amazing gains we had previously. On the old run, the throttle was released around 6200 RPM as our rear seal blew that time, so that's why the dyno goes down drastically towards the end.
I failed to point out that my Chevy SS sedan is of the Zeta platform 2014-2017. Harrop wasn't sure about the fit-up, as the difference between the right-hand drive engine bay (Aussie) is different, and they don't any reference to a left-hand drive (USA) configuration. I think the AC hard lines on the Chevy SS version is a potential issue. If I proceed, it's likely I would be the first to try it on this particular body type.
I always say, if it fits in a Corvette, it'll fit in anything. Up top you have plenty of space. On the sides you may have to move the ABS module. On the RHS valve cover, you will need to shave off the oil fill port. Or you may get away with putting that valve cover onto the LHS so the oil fill port would be all the way in the back, behind the airboxes. Of course, our airboxes are much more space efficient than the cast ones from Harrop, and you don't need to buy 2000$ CNC valve covers for them to fit
I finally got the final dyno results with the complete Hurricane/FluiX setup at good weather. The power increased by about 10-15 hp above 4500 RPM. The first image shows this dyno run. On the second image I plotted all important data on one plot for easier comparison between the old intake/intake manifold setup vs. the Harrop/FluiX one. The plot compares corrected flywheel power.
The values through 55 rpm would most certainly satisfy me. Not sure how to interpret what's going on @ 3800-4000, but I'm pretty sure I could live with it.
The values through 55 rpm would most certainly satisfy me. Not sure how to interpret what's going on @ 3800-4000, but I'm pretty sure I could live with it.
The dip at 3800RPM is when the reversion reach the point between the 4th and the 3rd harmonic. In other words, the reversion wave just hits the inlet of the runners instead of hitting the intake valve. It's quite normal, but intakes with shorter runners would be between the 5th and 4th reversion there, and the higher you go on the reversion number, the smaller the effect of the waves will be. So on a normal intake it's there as well, just not as apparent.
The dip at 3800RPM is when the reversion reach the point between the 4th and the 3rd harmonic. In other words, the reversion wave just hits the inlet of the runners instead of hitting the intake valve. It's quite normal, but intakes with shorter runners would be between the 5th and 4th reversion there, and the higher you go on the reversion number, the smaller the effect of the waves will be. So on a normal intake it's there as well, just not as apparent.
So, something like my Plazmaman Manifold may produce less power-band torque at the same point? These go with my Plazmaman (unused) manifold w/102mm in my previous post (above). I suspected it had something to do with 'reversion; just a bit fuzzy on the topic. I've wanted the Hurricane for quite some time.
Perhaps I'm obsessing over swapping out the Plazmaman in favor of the Hurricane; thinking the difference in improvement may be too small. I have yet to find any test numbers on the Pazmaman - only rumors. Anyway, would appreciate your thoughts.
Last edited by Saber-1; 11-12-2018 at 10:17 AM.
Reason: more to say...
So, something like my Plazmaman Manifold may produce less power-band torque at the same point? These go with my Plazmaman (unused) manifold w/102mm in my previous post (above). I suspected it had something to do with 'reversion; just a bit fuzzy on the topic. I've wanted the Hurricane for quite some time.
Perhaps I'm obsessing over swapping out the Plazmaman in favor of the Hurricane; thinking the difference in improvement may be too small.
An intake that works on a lower reversion will always make more power, but you will have those dips throughout the RPM band. The problem is, making the power at the right RPM. So if at 7000 RPM the Harrop is in between the 3rd and 2nd reversion at its worst point, an intake that just hits the sweet spot of the 3rd reversion will probably make more power at that RPM. But anywhere else the long runner intake is superior. The second reversion on the Harrop would hit its sweet spot at 7500RPM. Again, the lower the reversion count, the higher the pressure waves strength. So if an engine were to hit that 2nd reversion, that would yield a huge power bump at that RPM. After that if you would rev even higher, when you'd get in between the 2nd and 1st reversion, there would be a huge power loss though, until the 1st reversion is timed just right again.
But to the Plazmaman, I'm not too familiar with that intake and how long its runners actually are. From pictures they look very short (3-4 inches?), and that they don't extend into the manifold themselves. That would be a good intake for high boost forced induction, just because the billet can take the force and heat. But it would loose power over a MSD intake (I think it has approximately 7 inch runners) for sure. Even for forced induction it would loose power over an MSD, but it's not quite as apparent on forced induction setups as NA. NA is where the art of intake/RPM matching really shines.
If the Haroop airboxes don't fit under the hood then let me know . And really, the Hurricane is not that difficult, especially if you have the option of a MAF as I do.
I remain interested in the Hurricane manifold, but how did you tune the air fuel ratio? Not sure if the ITB meters both, or you incorporated individual vacuum lines back to the vacuum box/MAF? If so, I would appreciate knowing how you accomplished this e.g. photos, etc.. I was reviewing the video at time stamp 1:00–1:38 and I was curious.
I remain interested in the Hurricane manifold, but how did you tune the air fuel ratio? Not sure if the ITB meters both, or you incorporated individual vacuum lines back to the vacuum box/MAF? If so, I would appreciate knowing how you accomplished this e.g. photos, etc.. I was reviewing the video at time stamp 1:00–1:38 and I was curious.
The Hurricane has a small common plenum below the linkages, connecting all 8 runners. This is where you get your vacuum signal from. So for speed density you then have your pressure information, RPM, and with a temperature sensor you have enough to calculate density. Obviously, when you use the MAF version, everything works as it does on the stock car, besides that you need to scale your MAF information as with some of the aftermarket intake pipes.
The Hurricane has a small common plenum below the linkages, connecting all 8 runners. This is where you get your vacuum signal from. So for speed density you then have your pressure information, RPM, and with a temperature sensor you have enough to calculate density. Obviously, when you use the MAF version, everything works as it does on the stock car, besides that you need to scale your MAF information as with some of the aftermarket intake pipes.
Thank you for that helpful information. I wasn't aware of the integration, and that I can specify a MAF version from Harrop.
BTW, my raised hood finally arrived from New Zealand so the Hurricane should fit without any interference. I would still solicit your help for a clean tubing transition to the Harrop air/filter intake (post #30 pic-1). Granted, it requires quite a prep work, but you may get the idea.
Last edited by Saber-1; 11-23-2018 at 09:12 AM.
Reason: more to say...
10-08-2018, 06:42 PM
