Smifee Posted March 31, 2023 Posted March 31, 2023 Probably asked a million times but what's the clearance like on a front mount turbo? Looks like there a bit tight.. Quote
rerb Posted March 31, 2023 Posted March 31, 2023 I had more issues with the frame crossbars than the wheel/fender. I cut out the lower cross and had to shave away at the upper one to clear the wastegate actuator rod, this is with the proboost merge collector. Stock oil cooler lines also wouldn't play nice between the headers so I had to upgrade to stainless. Quote
Smifee Posted March 31, 2023 Author Posted March 31, 2023 I'm more worried about riding hard and the wheel hitting under braking, I'm a track racer so abuse the front end, thinking a under seat turbo maybe a better option Quote
clivegto Posted March 31, 2023 Posted March 31, 2023 12 minutes ago, Smifee said: I'm more worried about riding hard and the wheel hitting under braking, I'm a track racer so abuse the front end, thinking a under seat turbo maybe a better option When building your headers drop the forks through the yokes to check front wheel clearance. You can off set the turbo if needed or even grind a bit off. First time I put one together then went for a test ride pressed the front brake and the front wheel locked up. Scarry shit, b12 kit on a 7.5 slabby. I quickly modified the headers to fit correctly Quote
TLRS Posted March 31, 2023 Posted March 31, 2023 Forks bend too so make sure you have a little extra. If need be try fit something soft that wears very easy so you can verify the room required. Quote
TiZiK Posted May 9, 2023 Posted May 9, 2023 On 3/31/2023 at 6:09 PM, TLRS said: Forks bend too so make sure you have a little extra. If need be try fit something soft that wears very easy so you can verify the room required. How much you think forks actually bend? Serious question. I use old fork tubes as breaker bars and they are tough as nails. I'm running a Holset HY35 on a slabby and also had to remove the crossbrace and shave down the other mount on the left side for proper clearence. I have a good 1.5inches between the turbo and tire but this fork flex claim is always looming in the back of my head so I'm really curious about how much flex there actually is? Quote
Arttu Posted May 9, 2023 Posted May 9, 2023 I haven't ever tested this by myself but I recall estimations around 10mm from other people. So you should have at least that much clearance when the forks are fully compressed. 1 Quote
imago Posted May 9, 2023 Posted May 9, 2023 38 minutes ago, Arttu said: I haven't ever tested this by myself but I recall estimations around 10mm from other people. So you should have at least that much clearance when the forks are fully compressed. You do hear figures and guesstimates from time to time for fork flex, but "How much do forks flex?" is like asking "How much will the power increase be if I fit a turbo?". There are some obvious things involved, such as the larger the fork diameter the more resistant to flex they will be. Also things like USD forks are much more resistant to flex due to the much longer outer tubes. The real answer is way more complicated of course. Forks of what length? What's the bike's mass? What's the grip loss point of the tyre fitted? etc. With all the possible variables there isn't a reliable figure for fork flex. The only vaguely useful rough guide I've ever heard of (which ties in to the 10mm thing) is; for conventional forks you should be able to get your hand between the tyre and anything behind it (turbo, frame, headers) as the minimum. For USD forks you should be able to get your fingers all the way between the tyre and anything behind it. For a lightweight modern bike with large dia thin wall USD forks like a GSXR1000 then you should be able to get the tips of your fingers between the tyre and anything behind it. Obviously that adds another variable, who's hand? but as it's a rough guide you're looking at an average. 1 Quote
clivegto Posted May 9, 2023 Posted May 9, 2023 It's not a good idea if the front wheel can touch the turbo. Don't ask me how I know I just do 1 Quote
BillyR Posted May 10, 2023 Posted May 10, 2023 It really depends on the frame, something with less rake is always going to be tight. A friend of mine with a slabbie turbo has a simple trick, to get good clearance on his front mount he just taped a section of 1.5" thick foam pipe insulation to the front tyre while he put it together. Never had any problems. 1 Quote
TLRS Posted May 10, 2023 Posted May 10, 2023 To add another variable.. speed. Might grow the tire a tiny bit. Without having any realworld figures, 10mm seems plausible everything considered. Maybe someone curious with a running bike can do some tests. Video maybe or the foam? Quote
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