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Carbon airboxes with the Harrop Hurricane on an LS7

 
Old 12-27-2018, 10:35 PM
  #81  
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This thread is awesome, exactly what I wanted to see. I am building a G8 that is getting lots of goodies, but I've been looking for good info on the ITB setup. This car will be LSX454, 2" long tube headers and dual 3.5" exhaust. I've wanted to run the Harrop ITB for some time now, but had questioned the benefits. This build will be strictly N/A, so I'm looking for every advantage.
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Old 12-28-2018, 05:19 AM
  #82  
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Originally Posted by Floorman279 View Post
such an awesome looking setup. congrats....you did say that there were small stroke ls7s running this up to 8000 rpms? how come the 427 (i think thats your test car displacement) seems to be dropping off pretty fast at 7000?
It has to do with the stroke rather than the displacement, as stated in one of the comments. A shorter stroke allows for the 8000 RPM redline. When you increase RPM the time of one revolution of the engine decreases as well as the valve events. This then favors the acoustic reversions in the intake runners, which account for the large power increase above 7000 RPM. At around 6600 RPM these reversion waves have horrible timing with the intake valve opening event, therefore creating the torque/power drop.
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Old 12-28-2018, 05:23 AM
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Originally Posted by lstvr View Post
I see another Maha dyno test!? This one is interesting for me as i can see another comparable dyno sheet, as opposed to the ones in the US where the power figures seem to be so much bigger, you Americans must have some kind of magic air
My graph here is a Kinsler 55mm ITB set up on a 419CI LS3 (4.085x4.00") AFR Cathedral 245 heads.
The lower graph on my one Here is a 454LSX with a Fast 102 on the top.
Haha I agree! The dynos posted with similar setups are sometimes up by 100hp when they convert the RWHP to engine power with the 15% drive train loss . Your graph seems to be right on the money!
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Old 12-28-2018, 05:30 AM
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Originally Posted by LongShotPerformance View Post
This thread is awesome, exactly what I wanted to see. I am building a G8 that is getting lots of goodies, but I've been looking for good info on the ITB setup. This car will be LSX454, 2" long tube headers and dual 3.5" exhaust. I've wanted to run the Harrop ITB for some time now, but had questioned the benefits. This build will be strictly N/A, so I'm looking for every advantage.
Your main benefit will always be the throttle response. On bigger cube engines, ITBs will generally yield more power because you are replacing the one 92mm or 102mm throttle body by 8 60mm ones, which cause less restriction. On the Harrop example, the runner lengths will also cause you to pick up huge power between 3500 to 6200 RPM. You'll be up by about 50 hp in that RPM band. With the drive-by-wire it's also relatively easy to drive. The only real drawback is price
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Old 12-28-2018, 09:11 AM
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Originally Posted by FluiX View Post
Your main benefit will always be the throttle response. On bigger cube engines, ITBs will generally yield more power because you are replacing the one 92mm or 102mm throttle body by 8 60mm ones, which cause less restriction. On the Harrop example, the runner lengths will also cause you to pick up huge power between 3500 to 6200 RPM. You'll be up by about 50 hp in that RPM band. With the drive-by-wire it's also relatively easy to drive. The only real drawback is price
So with the longer stroke of the 454, would you suggest aiming to have a camshaft with peak power lower in the RPM range, say around 6400-6600? I'd be perfectly fine with that honestly, because I can put all the dry sump oiling and valvetrain money it would take to spin over 7500 into something else.... Like sending it to Harrop sooner, for example :p

I also really like the feedback I'm seeing about ITB setups taming down bigger cams at idle and part throttle, that's really good news. What is the science behind that, something about intake vacuum pulses conflicting with each other in the manifold?
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Old 12-29-2018, 07:09 AM
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Originally Posted by LongShotPerformance View Post
So with the longer stroke of the 454, would you suggest aiming to have a camshaft with peak power lower in the RPM range, say around 6400-6600? I'd be perfectly fine with that honestly, because I can put all the dry sump oiling and valvetrain money it would take to spin over 7500 into something else.... Like sending it to Harrop sooner, for example :p

I also really like the feedback I'm seeing about ITB setups taming down bigger cams at idle and part throttle, that's really good news. What is the science behind that, something about intake vacuum pulses conflicting with each other in the manifold?
The 454s I see usually are revved to about 6500 anyways. But for those you just aim your camshaft where you want the power band and the Harrop will just give you that extra push between 3500 to redline, regardless of the cam. When you rev to 7000, that's when playing with the cam starts getting important when using the Harrop, so that you don't have that drop in the power towards redline.

But yea, an ITB does tame a cam. This is due to the fact, as you mentioned, that at part throttle the reversion waves are captured inside the runners, since the almost closed throttle blade doesn't let them escape into the plenum or the airboxes. This means they reversion waves in one runner do not interfere with the other cylinders, which usually causes the buckling effect on cammed cars with a single throttle common plenum manifold.
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Old 04-22-2019, 07:53 AM
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Originally Posted by FluiX View Post
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.
I would like to know the characteristics of the Hurricane in city traffic/daily driving? I am closer to deciding on this intake for my custom 427 build.
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Old 04-22-2019, 11:10 AM
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Originally Posted by Saber-1 View Post
I would like to know the characteristics of the Hurricane in city traffic/daily driving? I am closer to deciding on this intake for my custom 427 build.
As long as your tune is good, itís just as easy to live with as the standard LS intake. On my car, the tune on MAF almost provided a smoother ride than SD. But for that you really need a clean air routing in front of the MAF, otherwise you will get a bad signal.

If you have a cam where you have buckling below 2000 RPM, then the Harrop/FluiX intake setup is much smoother than with a single throttle body intake. Depending on the cam you may not completely get rid of buckling, but youíll reduce by a very noticeable amount.
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Old 04-22-2019, 02:27 PM
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Originally Posted by FluiX View Post
As long as your tune is good, it’s just as easy to live with as the standard LS intake. On my car, the tune on MAF almost provided a smoother ride than SD. But for that you really need a clean air routing in front of the MAF, otherwise you will get a bad signal.

If you have a cam where you have buckling below 2000 RPM, then the Harrop/FluiX intake setup is much smoother than with a single throttle body intake. Depending on the cam you may not completely get rid of buckling, but you’ll reduce by a very noticeable amount.
Thank you for the useful information.

Last edited by Saber-1; 04-23-2019 at 06:40 AM. Reason: more to say...
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Old 04-23-2019, 08:08 AM
  #90  
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This setup will fit in an fbody with a little work btw
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