fast 90 losses?
Thread Starter
Joined: Aug 2005
Posts: 2,649
Likes: 1
From: Mont Belvieu, TX
fast 90 losses? I have been reading a l ot lately about the fast 90 becoming a restriction on higher h.p. levels. What I was wondering was at roughly what point does this beome an issue. You can see from my sig what size engine that I am building and I know that around 550 rwhp is pretty consistent for that size. I am looking to get about 30-40 more, and I was wondering what flow I would need out of a head intake combo to achieve that and still retain decent street manners. I am kind of a half *** budget, so I was wanting to stay away from the really exotic **** if you know what I mean. I will be working on this for over a year and plan on picking up the top end parts a little at the time, so I want to have a pretty firm idea of what I will need going in so if a good deal comes up, I can grab it. I am kinda new at this so, please bear with me on any stupid questions. thanks.
There is a calculation (that I don't know) that can tell you how much intake air flow you need to make X amount of HP. I would say that for a car to make 550-660 rwhp you would have to have about 300cfm or more of air flow on the intake side and about 70-80 percent of that on the exhaust side. This is for a NA combo and a forced induction combo would not require as much air flow since you would be forcing air into the intake runner. Just a little food for thought.
Thread Starter
Joined: Aug 2005
Posts: 2,649
Likes: 1
From: Mont Belvieu, TX
Thanks. I have read that for every cfm of flow you can produce a little over 2 hp. i think that this is fwhp. Does any one know the formula exactly? Also what is the highest anyone has heard out of a ported Fast 90? I noticed that BYUNSPEED has a 96 mm intake and t.b on their site, has anyone used this? Or know anyting about it?
That is correct the calculation is for FWHP but do a 15-20% power lose for the drive line and that should get you in the ballpark. Either way good luck with the combo it lloks as if you have a very well thought out plan and I hope it runs better than you antisipate it to.
I've seen 580-600rwhp out of the FAST90 on 93 octane friendly 447s. I don't think you can get much more out of them. The FAST 90 can flow low 300s if you port the **** out of it, but the real problem is valve shrouding with smaller bores. That's why most 402/408s aren't really making a lot more power over 346s with similar sized camshafts. Anything over 4.125" bore and heads that flow well can produce power when matched to a FAST90.
Thread Starter
Joined: Aug 2005
Posts: 2,649
Likes: 1
From: Mont Belvieu, TX
Originally Posted by JakeFusion™
I've seen 580-600rwhp out of the FAST90 on 93 octane friendly 447s. I don't think you can get much more out of them. The FAST 90 can flow low 300s if you port the **** out of it, but the real problem is valve shrouding with smaller bores. That's why most 402/408s aren't really making a lot more power over 346s with similar sized camshafts. Anything over 4.125" bore and heads that flow well can produce power when matched to a FAST90.
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