Fast 78 vs fast 92
08-15-2018, 11:44 PM
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Fast 78 vs fast 92 Wondering the difference between a fast 78 and fast 92 I have a 2001 z28 a4 with ported 243s btr racing stage 4 cam longtubes 3 inch exhaust yank 3600 stall and wanting to put a 150/175 nitrous shot just to get the best performance results also would I be able to port the fast 78 to a 90 or 92mm tb
08-16-2018, 03:52 AM
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The 92 needs a different throttle body whereas the 78 can use the stock one. Of course the 92 makes a little more power. Also are you asking can the 78 accept a bigger TB like a 92mm?
08-16-2018, 12:38 PM
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Fast 78 vs fast 92 yes I’m wondering I know the fast 78 is an older intake I got it for a pretty good deal and it’s in great shape. I know the runners and easily be ported but what about the snout for say like a 92mm throttle body I know the factory can be ported but I’m wanting to go bigger since my cam specs are 621/594 238/242 btr stage 4
08-16-2018, 12:44 PM
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Well I know they make a kit that allows the LS6 intake to accept the 90/92 throttle body, so I'm sure it can be done, but don't know who would do it. Since you already have the 78 I'd get it ported along with your throttle body. That would save some money and still get you some nice gains
08-16-2018, 12:52 PM
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Every intake known to man was tested a couple years ago on an lsx engine. It was a built engine making good power so your gains may or may not be the same. I just happen to have the test results printed out at my desk.
For comparison:
LS6 intake - 557hp/483tq
FAST 78 - 571hp/490tq
For comparison:
LS6 intake - 557hp/483tq
FAST 78 - 571hp/490tq
08-16-2018, 12:55 PM
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Fast 78 vs fast 92 So I shouldn’t go with a bigger throttle body on my fast 78 just a proper port and bolt it back on? And how much horsepower would I gain if I were to put a 90/92 tb
08-16-2018, 02:22 PM
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Ok so then that tells me it’s basically not worth to even do a 90/92 Tb because wouldn’t be adding much more hp for the money so should I just use the 78mm off my Ls6 intake or just buy an aftermarket 78 the fast didn’t come with the Tb
08-16-2018, 04:40 PM
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08-16-2018, 06:07 PM
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Maybe it was ported 78 would be close to stock 92mm. Either way. Even the fast 78 is great over the ls6. In that awesome test of the intakes. Just seeing the max numbers doesn't do the intake justice. As the tq peak changes rpm. Where the ls6 was getting past 450 at 6500rpm & the fast 78 is climbing past 450 at 5700rpm. The 92 may make a little more power but the 78 is still an awesome intake.