Cranks for boosted applications.
Little bit of a noob here when it comes to boosted Pontiac but I wanted to get a general understanding on y’all’s experience and opinions on cranks.
I’m in the initial process of collecting parts for a Boosted drag and drive motor. A couple months ago I called Frank at All Pontiac and made a deposit on an aftermarket iron block. While talking to him, he recommended a 4.25 bore and 4.25 stroke Billet crank. I’ve seen previous threads from a couple years back where people have stated keeping the stroke shorter would be ideal and even some have said 4.00 and under, but I’ve also seen a few guys successfully running a longer stroke successfully. What’s the current consensus in stroke? I’m looking to build something capable of mid nines initially with room to grow as I gain more experience with the combo. So I’m figuring in a 3600lb car I probably need to be in the 1k-1200hp range? Am I crazy? |
have you received your block? i put my deposit down 2 months ago as well and hoping it gets here soon.
frank rec'd me to go with a 4.35 bore with my roots blown build and at the time i was gonna use my 4.0 crank . i instead used that crank in my 400 and going to run a 4.250 crank in the ia2 block with a procharger. seams like 4.0 and 4.250 is the general consensus on boosted apps even using a new block |
IMO the smallest stroke is the way to go. I go mid nines with a 3.75" stroke with a 198ci motor . More stroke will just make it harder to get down the track ..
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It seems like a decent amount of guy’s suggest the shorter stroke I’m just trying to better understand why. And those billet cranks are a big purchase. |
The reason why is that with a turbo torque becomes so multiplied it becomes a problem to get traction. So a short stroke will help you in that respect.. You still will have more torque then you will need with the shorter stroke. Im building a motor now with 3.330 stroke because even with 3.750 stroke it was too much imo...
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Lots of big power boosted Pontiacs with 4 inch strokes out there. Its what Chief ran.
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A YSi Vortech Supercharger would make 1200 in a street car with a basic BB Chevy engine years ago. A Procharger supercharger can easily make the same power. A boosted Pontiac Turbo Engine (one turbo) would require a Large turbo (or 2 turbos ) and would be very soft on the bottom unless paired with a 400+ cid engine. Tom V. |
Mine is a 400 ci 60-over make's a ton of power no dyno numbers.
I just bump the cam a bit to a solid roller I'm hoping for 1-1200hp with iron heads, When I get the 77-firebird done I'm going to install it in that might be a while unless I just have to know and put it one of my other cars. I might dyno it this time too. GT |
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