Arrow 88mm crankshaft

[Karlheinz]

Hi guys,
I saw in the Arrow website this product, but I found two version:
- normal 88mm
- narrow 88mm.
Well: what are the difference?!?!?
Thanks.

[andy escos]

no idea on your question but i heard the 88 mm crank is no good for high revs .8500 +rpm

[SCS j1mbo]

Narrow journal or normal journal

Narrow journal is 49mm big end size and normal 52mm big end size.

Normal journal is stronger

[Karlheinz]

Thanks a lot J1mbo

[SCS j1mbo]

Welcome

[Karlheinz]

I think that a 2288cc (91mm pistons with 88mm crank)
YBP produce a lot of torque

[Boostjunky]

Whats the benefits if haing a narrow journel.?
If any..?

Reason i ask is as jimbo said normal is stronger, so why did they make a narrow one .?

[SCS j1mbo]

I personally would go up to a 92mm bore size and use an 84/82 crank as an 88mm crank is alot of crank!

The narrow journal crank was done to allow the fitment without having to take the sides of the block away

[steveboyslim]

Narrow journal or normal journal

Narrow journal is 49mm big end size and normal 52mm big end size.

Normal journal is stronger

I would argue that the narrow is stronger, less distance between the counterbalance weights.
The narrow journal crank was done so that the counerbalance weight can be less creating less flex in the crankshaft so that the bearings do not get such a hard time.

Steve

[MK Motorsport]

I would argue that the narrow is stronger, less distance between the counterbalance weights.
The narrow journal crank was done so that the counerbalance weight can be less creating less flex in the crankshaft so that the bearings do not get such a hard time.

Steve

HI steve
wouldnt bearings get a harder time being narrower less suface area , less support ,faster wear

mark

[steveboyslim]

HI steve
wouldnt bearings get a harder time being narrower less suface area , less support ,faster wear

mark

To a degree yes, but a BDA/G/X , BDT and BDT/E uses the narrow size bearings as do many of the division 2 rallycross engines, reduced reciprocating mass giving the bearing less of a hard time.

Steve

[SCS j1mbo]

Steve is your theory based on what other engines use and what abuse they have taken

Or through testing each to breaking? I've seen narrow journal cranks snapped clean through the big end before not normal

[MK Motorsport]

To a degree yes, but a BDA/G/X , BDT and BDT/E uses the narrow size bearings as do many of the division 2 rallycross engines, reduced reciprocating mass giving the bearing less of a hard time.

Steve

hi steve
i thought narrow journal was done for less surface area means less drag etc ok for a race engine ,and arnt the above race engines, that are designed to be stripped after a meeting ,when i worked at race teams this was done after every race, ok for racing not what you want on a road track car surely ? so i would have thought normal journal best and with the extra support of a full width bearing much better

mark

[steveboyslim]

Steve is your theory based on what other engines use and what abuse they have taken

Or through testing each to breaking? I've seen narrow journal cranks snapped clean through the big end before not normal

From what has been used and is in use in rallycross and from the designer of the crankshaft.
I have not seen an Arrow narrow YB break although I have seen other brands break.
I must admit I do not full understand the design side of crankshafts, I am told it is to do with engine harmonics and counterbalance weight single or double.
As an example, although not a YB, SCS has built several BDT/E engines with 700+ bhp, they have the narrow bearings with a double counter balance crank.

Steve

[SCS j1mbo]

From what has been used and is in use in rallycross and from the designer of the crankshaft.
I have not seen an Arrow narrow YB break although I have seen other brands break.
I must admit I do not full understand the design side of crankshafts, I am told it is to do with engine harmonics and counterbalance weight single or double.
As an example, although not a YB, SCS has built several BDT/E engines with 700+ bhp, they have the narrow bearings with a double counter balance crank.

Steve

I am the same and am not entirely clued up on cranks steve but I know what I see withh my eyes. And we always stick with normal journal due to seeing the one broken, more so a just in case attitude as we also only use arrows cranks now.