17 replies to this topic

[CPC]

I would just like a opinion on this cylinder head i have.  I have not measured the cc yet, but it has 37mm inlet and 29mm exhaust valves and some fairly heavy porting.   But i don't know if the chambers have been opened up.

 

 

This is being used on a 1380 with 11cc megadish pistons with a 266 cam NA engine at the moment with a 3.1 diff.

 

Basically what im asking could i leave my bottom end as it is and just have the head modified to leave with with a sensible compression ratio to either turbo or supercharged application

Edited by CPC, 15 June 2017 - 08:49 AM.

[hazpalmer14]

What size are the chambers?

[mini13]

37 x 29 is a bit close unles the valves are already offset, it may be likly to crack.

 

compression wise you might be able to get away with it with 18vv pistons, but we need to know the chamber size

[CPC]

The valves are very very close, its still leaded as due to clearance

 

[Midas Mk1]

If you think thats close, i've got a 37 32 head on my 1380 , rizzla paper comes to mind aha 

[r3k1355]

Whats the spec on the cam?

Would it be suited to turbo or would a different one be needed?

[mini13]

Don't like the look of that transition from valve seat to port, looks rather abrupt.

[neal]

A lot of heat is generated with forced induction and you'll need really effective cooling in that area to keep it from cracking, not sure how long it would last with the small gap between the valves.

[r3k1355]

A lot of heat is generated with forced induction and you'll need really effective cooling in that area to keep it from cracking, not sure how long it would last with the small gap between the valves.

 

Water/Meth injection might be a good idea for that issue.

[Turbo Phil]

If the chamber size gives the correct compression ratio for your application there's no specific reason why you couldn't use the head, although the valve sizes are far from ideal from the point of view of both reliability and power output.

Phil.

[HUBBA.HUBBA]

What valve sizes are ideal? Out of interest

[neal]

I'd go no further than 35.7mm inlets and 29mm exhausts on well shaped ports/combustion chambers, but I suppose it depends how bonkers you want to go and are you willing to forfeit a reliable unit for a little more power??

Edited by neal, 16 June 2017 - 06:29 PM.

[HUBBA.HUBBA]

Just thinking that I have a standard spi head I can use for my new super charged desert rat project. Not too fussed about massive power. Wouldn't want to be quicker than my mini! Stuart G Hinted to me the that a decent inlet is where you get the most power for a super charged set up. Presumably so it can suck more air in

[Turbo Phil]

A 29.4mm exhaust will work fine in combination with a 35.7mm inlet. There is a benefit in going larger on the exhaust though. When fitting a 31mm exhaust with the 35.7mm inlet I usually offset the exhaust valve to keep some material between the valves.

Phil.

[HUBBA.HUBBA]

A 29.4mm exhaust will work fine in combination with a 35.7mm inlet. There is a benefit in going larger on the exhaust though. When fitting a 31mm exhaust with the 35.7mm inlet I usually offset the exhaust valve to keep some material between the valves.
Phil.

Sorry when I was saying inlet. I meant the inlet to the super charger. I generally thought that a supercharger needs a large inlet to breath and then ram air into the block. No matter what size of valves the mixture would be forced in?

Edited by HUBBA.HUBBA, 19 June 2017 - 02:53 PM.