Steve's MK2 Sports Sedan

[SportsSedanSteve]

Does 11.8mm inlet lift count as "wild"

Danny's recommendation was the BDA F1 springs. Handle the lift and the revs easily. My REC Gold springs were cheaper by a bit(not much) and have better dynamics than the Isky springs.

[Danny M]

Steve what's the numbers on the cams and how come you didn't weld up the chambers a's you really need the compression

[SportsSedanSteve]

Danny, have a closer look at the chambers. Theirs nothing of them and after the final skim the heads at 137mm.
Cams are Tighe's. Same as been supplied to Belly as far as I know. Specs as attached:
Exhaust cam: CL 106 0.006 311.19 83.67 BBDC 47.52 ATDC Valve lift .448"
Inlet cam : CL 102 0.006 328.07 64.11 BTDC 83.96 ABDC valve lift .461"

I realise getting the required valve clearance will mean machining more out of the valve reliefs but they have to be sorted to suit the bigger valves anyway. Choice of head gasket will be critical. chambers haven't been cc'ed yet.

[Danny M]

Steve those chambers are still far too big
What numbers are on the cams as I have other listing that will give me more info

[SportsSedanSteve]

I ended up editing out most of the info on the cams.
They are Tighe's 440/441.
I'll PM the full camsheet.

[Danny M]

How big are your valve reliefs

[SportsSedanSteve]

Danny, the valve reliefs on the Accralite's are 4mm inlet and exhaust. The piston crown thickness is +.300". There should be enough meat in them to fly cut the valve reliefs deeper to suit the valve lift but how much we won't know until the dummy build.
Do you know from experience what's the safe limit is for crown thickness for an N/A engine with forged pistons?
When i get back home I'm going to do a quickie CC on a chamber because without the exact numbers I can only guess on static compression and I can't model it properly with my software.

Did the camsheet come through on that PM ok?

[Danny M]

The absolute minimum thickness from the deepest point of the pocket to the underside of the crown is 0.200"!
With those camshafts you will need at least another 0.100" on the inlet and 0.080" on the exhausts
Also you will find that you will really want to fit a bigger exhaust cam as that is the combination I started with and the engine will make more expery especially in the mid range with a 440c in both
Also you will have to replace you springs as they wont last long especially with that exhaust profile
I don't need the sheets for those as I have most of them and I have the master sheets for everything he's got over 0.400" on a 1 to 1 profile

[Roger Miller]

Dan,

From memory you said once the after market Kawasaki springs were not up to the task.

Whats his options ?

[Danny M]

Cosworth

[SportsSedanSteve]

Been off the net for a few days

So Danny, am I in trouble with these Accralite pistons as far as crown thickness remaining after the reliefs are machined deeper?

[Danny M]

Without laying eyes on them I would think they'll be too thin

[SportsSedanSteve]

I'll measure the crown thickness myself when I get home next Tuesday and get back to you then.

Which Accralite piston did you get your .200" measurement from? The .300" measurement I mentioned before was done by Milton's who did the head work and block for me. I will say that he did it with verniers and he did say "roughly" .300" plus.

Maybe I should be looking at CP or Woessner pistons. I remember you saying sell em last year!!

[Danny M]

0.200" is the usual rule for minimum crown thickness

[SportsSedanSteve]

Well, they are pricks to measure properly. I'm getting something like 6.24mm to 6.4mm at the centre of the inlet valve relief.
There is extra material in the forging around the bosses for the gudgeon pin but machining the valve reliefs will directly affect the strength of the piston here I'm thinking.

[Belly]

Hey Steve, sound like you are trying to do this properly if so, put some good Pistons in it, get the CP's that myself and Danny use and you will have no problems, do it correctly the first time you will save some money in the long run and weld the head up, put it in and forget it - I have spent so much money on Engines and cars and I have learnt do it properly the first time

Belly

[SportsSedanSteve]

Is there a CP part number for these pistons or are they a custom design?
Will they suit the 136mm "long rods". I haven't got the little end specs here with me either.
The block is already honed to suit the accralites.

[SportsSedanSteve]

Dummy build on hold for another week till Mike has more space in his engine room. Guess the answer to the big question will have to wait for a bit longer.

[Roger Miller]

[SportsSedanSteve]

Stupid server up here won't let me look at photobucket pics

Roger, any chance you can upload them to the forum as per normal so I can see them?