Crank with Type 1 main or Type 4 main?

[runningmonkey]

Hi all

Am building a 2332 which am going to turbo and EFI (using CB performance kit)

Iv just bought a 84mm Scat Crank with type 1 mains, but Iv been told what I really should have bought is a crank with a type 4 main bearing?

Could someone please tell what the benefits are of using the type 4 bearing? and am I still going to be ok with my type 1 bearing crank?

Cheers in advance John

[UltraOrange67-2443]

Hi John

T4 mains are stronger.

Sometimes they run a T4 center main.

The Crank can flex at high RPM.

What Crank have you got?

Maybe sell it and get something better, I like Scat Cranks.

Cheers, Nick

[Tufty65]

Hi all

Am building a 2332 which am going to turbo and EFI (using CB performance kit)

Iv just bought a 84mm Scat Crank with type 1 mains, but Iv been told what I really should have bought is a crank with a type 4 main bearing?

Could someone please tell what the benefits are of using the type 4 bearing? and am I still going to be ok with my type 1 bearing crank?

Cheers in advance John

The simple benefit is strength.
I used a type 1 main crank on a 2332 cb turbo motor and it held up for quite a few years but I had the crank assembly dynamically balanced too,all the pistons and rods matched,  it will be ok but will undoubtedly flex more than a t4 main crank will at high rpm.
If your case is a t1 mains bore you could use a t4 centre main crank and use the BMW conversion bearing so it will fit on your case without machine work.
The strongest cranks out there use all t4 mains and bigger but cost more.

[richie]

Hi John

the actual difference is type 4 mains being bigger size means crank has more overlap material between main journals and rod journals which makes crank stronger and less prone to flex. All type 4 mains creates a lot of other problems for case work though, type 4 center main only is not to bad to do mods to case.

Here's some real world experience, not just internet stories

I personally have a Scat 84mm type 1 mains crank I ran in Old cabrio for 8 years, starting as a N/A engine, then Nitrous engine, finally turbo engine and went as quick as 9.66 with, I then sold it and it went into another turbo car, was then sold and went into another turbo car and is still running today 17 years on , its never even been reground, just been polished once so yes it can work without type 4 mains
Its all about the tune & set up, even with type 4 mains if its done wrong it will still break!!!!

cheers Richie

[leec]

That's a great value crank there

[bedjo78]

Hi Richie

was the crankshaft wedgemated ?

[runningmonkey]

Hi John

the actual difference is type 4 mains being bigger size means crank has more overlap material between main journals and rod journals which makes crank stronger and less prone to flex. All type 4 mains creates a lot of other problems for case work though, type 4 center main only is not to bad to do mods to case.

Here's some real world experience, not just internet stories

I personally have a Scat 84mm type 1 mains crank I ran in Old cabrio for 8 years, starting as a N/A engine, then Nitrous engine, finally turbo engine and went as quick as 9.66 with, I then sold it and it went into another turbo car, was then sold and went into another turbo car and is still running today 17 years on , its never even been reground, just been polished once so yes it can work without type 4 mains
Its all about the tune & set up, even with type 4 mains if its done wrong it will still break!!!!

cheers Richie

Thanks Richie! That's put my mine at ease! Many thanks! 

[Andy]

Here's some real world experience, not just internet stories

I personally have a Scat 84mm type 1 mains crank I ran in Old cabrio for 8 years, starting as a N/A engine, then Nitrous engine, finally turbo engine and went as quick as 9.66 with, I then sold it and it went into another turbo car, was then sold and went into another turbo car and is still running today 17 years on , its never even been reground, just been polished once so yes it can work without type 4 mains
Its all about the tune & set up, even with type 4 mains if its done wrong it will still break!!!!

cheers Richie

Was that a Chevy journal crank.

I am in the middle of trying to to choose a crank for a new engine , either 2276 or 2332, for Strip and Street use. 😉

Cheers Andy.

[richie]

Hi Richie

was the crankshaft wedgemated ?

Later on in its life it was when turboed it was yes

[SSRT]

Hi John

the actual difference is type 4 mains being bigger size means crank has more overlap material between main journals and rod journals which makes crank stronger and less prone to flex. All type 4 mains creates a lot of other problems for case work though, type 4 center main only is not to bad to do mods to case.

Here's some real world experience, not just internet stories

I personally have a Scat 84mm type 1 mains crank I ran in Old cabrio for 8 years, starting as a N/A engine, then Nitrous engine, finally turbo engine and went as quick as 9.66 with, I then sold it and it went into another turbo car, was then sold and went into another turbo car and is still running today 17 years on , its never even been reground, just been polished once so yes it can work without type 4 mains
Its all about the tune & set up, even with type 4 mains if its done wrong it will still break!!!!

cheers Richie

Magnesium case or alu?

[bedjo78]

[/quote]

Later on in its life it was when turboed it was yes
[/quote]

thanks .. for good information you passed as always

[richie]

Hi John

the actual difference is type 4 mains being bigger size means crank has more overlap material between main journals and rod journals which makes crank stronger and less prone to flex. All type 4 mains creates a lot of other problems for case work though, type 4 center main only is not to bad to do mods to case.

Here's some real world experience, not just internet stories

I personally have a Scat 84mm type 1 mains crank I ran in Old cabrio for 8 years, starting as a N/A engine, then Nitrous engine, finally turbo engine and went as quick as 9.66 with, I then sold it and it went into another turbo car, was then sold and went into another turbo car and is still running today 17 years on , its never even been reground, just been polished once so yes it can work without type 4 mains
Its all about the tune & set up, even with type 4 mains if its done wrong it will still break!!!!

cheers Richie

Magnesium case or alu?

Mag case when N/A and nitrous, then ally for turbo

cheers Richie

[richie]

Later on in its life it was when turboed it was yes
[/quote]

thanks .. for good information you passed as always
[/quote]

   No problem

[Fastbrit]

Some more real world experience. Ran a welded 78mm stroker from Pauter, all VW journals, turbo and turbo with 50 shot nitrous, for five seasons (one in Flat Attack, four in No Mercy). Engine sold to Ken Blomer and then to Natashia Garcia for use in their cars. Crank never needed grinding, or straightening. Magnesium cases only.

OK, not a long stroke by today's standards, but if everything is carefully balanced, it's amazing how long old shit can last. T4 main bearing conversion was around at the time but all the related hassle never seemed to make it worth it, and I had no evidence it was needed in my situation...