Upgrading my 1915

[Erlend / bug66]

Hi

I'm upgrading my 1915 this winter..

Going from:               To:

Mahle 94               Mahle 94
Stock crank               DPR 69mm
Stock rods               CB Super Race 5,4” H-beam rods
Lightend flywheel            same flywheel
35,5x32 heads               044 Wedgeport 44/37 or 42/37
web 109               Web 86CorB (CB two piece lifters)
10-1 CR                  11-1 CR
weber 40 idf               48 IDA


What do you guys think? It's going to be a street/strip, needs to be able to ride to work (show off ) but SCC will be it's glory.

No, I'm not buying JPM raptor Kalle Need to be able to afford other things (got a car #2, bike etc)

[BeetleBug]

 

It`s hard to beat the 86C.

But more importantly is that you build something that can match the BIG heads you`re planing to use.

BB

[Erlend / bug66]

It`s hard to beat the 86C.

But more importantly is that you build something that can match the BIG heads you`re planing to use.

BB

11-1 and cam? 42 vents, shortend intake runners

[TexasTom]

If you're switching cranks, why not go with a 74?
Easier to make compression, minimaL shims, extra torque, more air flowing to make those ports work ...
 

[Erlend / bug66]

It's staying as a 1915

[TexasTom]

Just curious ... figured you had a reason.

I'd at least go with the smaller intake valve, 42.
Its gonna rev to the Moon!

[Torben Alstrup]

Wedge´s are too big. Stay Mini Wedge w. 42/37 and that thing will buzz.
Your largest challenge will be getting enough compression. Those heads needs to be flycut DEEP! and then you will run into piston to valve clearance problems.
OR call Steve Timms or Denham and ask to have made a set that suit your needs. Might be a better solution when you want to stay 1914.

T

[Erlend / bug66]

Just curious ... figured you had a reason. Yup: dare to be different

I'd at least go with the smaller intake valve, 42.
Its gonna rev to the Moon! Hope so!

[Erlend / bug66]

Wedge´s are too big. Stay Mini Wedge w. 42/37 and that thing will buzz.
Your largest challenge will be getting enough compression. Those heads needs to be flycut DEEP! and then you will run into piston to valve clearance problems.
OR call Steve Timms or Denham and ask to have made a set that suit your needs. Might be a better solution when you want to stay 1914.

T

Why? Airspeed?

[Zach Gomulka]

If you're switching cranks, why not go with a 74?
Easier to make compression, minimaL shims, extra torque, more air flowing to make those ports work ...
 

Agreed!

[Erlend / bug66]

It's staying as a sub-2L, only because I'm stubborn

So the 44/37 won't flow as good, because the motor won't pull enough AF-mix through the heads? (because of low airspeed)??

[andy M.]

Having had a little experience running a hi po 1914 I can see little wrong with your intended spec, my car runs 44 x 37 valves, fk 89 and 11.5-1 comp on the street and runs nice and cool on the way to work and back, and with a set of slicks on there it's knocking on the door of an 11 sec quarter. Admittedly it is quite light though...

Andy

[BeetleBug]

Car # 2 in this video has a 1915 ccm engine: http://www.facebook.com/photo.php?v=10150354696368350 180.8hp and it sounds really nice!

[Erlend / bug66]

Having had a little experience running a hi po 1914 I can see little wrong with your intended spec, my car runs 44 x 37 valves, fk 89 and 11.5-1 comp on the street and runs nice and cool on the way to work and back, and with a set of slicks on there it's knocking on the door of an 11 sec quarter. Admittedly it is quite light though...

Andy

What pistons? Notched?

[andy M.]

mahle with a notch, can't remember how deep, valves are ti with jpm springs and retainers,

andy

[Erlend / bug66]

I think I need to notch the pistons, or weld and reshape chamber to raise the CR.

[Erlend / bug66]

Is there any way other then a mock up to figure out how much I need to notch? Even that is probably a game of chance?

[andy M.]

First off you'll need to get the heads flycut for your desired compression ratio, then mock it up and see what happens, you might get away without notching but I doubt it,  my old set up with a 10.5 -1 ratio needed notching,

what happens with your set up all depends on lift and other variables.

andy

[Erlend / bug66]

Not my first engine, and I'll mock it all up. Can't wait!

Can we see 90bhp pr litre?

[andy M.]

that should be more than feasible

[Erlend / bug66]

whould my little 1915 flow enough through a 44mm intake valve, or should I use a 42mm valve and get some more speed through the valve. the manifolds will be shortened and ported all the way up to the carb.

hmm 

[Speed-demon]

why not buy a set of steve tims stage 2s they are 42mm.