[Technique] Projet monos

Sujet: Re: [Technique] Projet monos Dim 9 Mar 2014 - 18:59

fd-racing a écrit:: here is the pic of the cylinder head and the last cam i made , they are from my 100 hp engine , you cant see the intake , but there's no secret there , first diameter 50 mm and 2 x 34 mm , throttle body 52 mm , exhaust runner is stock

- 1.2 mm on the head surface in order to reach the 13.5 to 1 compression ratio

when you use the rally cam witch has 50 ° intake retard your compression ratio must be at least 13 to 1 if you want your engine running well under 5000 rev/min

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thank you for the info!!

Can you remove 1.2 mm of the head without the valves hitting the piston?! I have been thinking about it but didn't clay it yet so no idea... I have the 654 cc version btw ( 102x80 mm).

Sujet: Re: [Technique] Projet monos Lun 10 Mar 2014 - 11:45

if you take out 1.2 mm on the stock 654 cc head , you must take the same amount on the valves Pocket piston , on my big engine i run 105 mm custom piston made by Mahle racing in US

if you want to raise your compression ratio with the rally cam you have to remove 0.7 mm , or from the head with an special tool , or from the cylinder bottom , but you have to deal with the fact that your cam will advance 5/7 °

Sujet: Re: [Technique] Projet monos Lun 10 Mar 2014 - 14:22

fd-racing a écrit:: if you take out 1.2 mm on the stock 654 cc head , you must take the same amount on the valves Pocket piston , on my big engine i run 105 mm custom piston made by Mahle racing in US

if you want to raise your compression ratio with the rally cam you have to remove 0.7 mm , or from the head with an special tool , or from the cylinder bottom , but you have to deal with the fact that your cam will advance 5/7 °

I indeed want to raise the compression on my 654 cc engine, with the rally cam installed. So I can remove 0.7 mm from the head without modifying the piston or anything else?

Isn't the squish going to be very small near the outside of the cilinder? Thanks for the info!

MJ

Sujet: Re: [Technique] Projet monos Lun 10 Mar 2014 - 15:11

if you milled the head the squish will remains the same , it's 1.2 mm on stock engine, you may control your valves to piston distance.

if you take the 0.7 mm on the cylinder bottom , your squish will be 0.5 mm , its not enought , a minimun of 0.9 mm is required , so you can take 0.4 mm , on the top of the piston , just at the squish area .

as you see it's not an easy job , that's why people normaly run the rally cam with stock comp ratio [Technique] Projet monos - Page 3 584741

[Technique] Projet monos - Page 3 584741

Sujet: Re: [Technique] Projet monos Lun 10 Mar 2014 - 20:15

fd-racing a écrit:: if you milled the head the squish will remains the same , it's 1.2 mm on stock engine, you may control your valves to piston distance.

if you take the 0.7 mm on the cylinder bottom , your squish will be 0.5 mm , its not enought , a minimun of 0.9 mm is required , so you can take 0.4 mm , on the top of the piston , just at the squish area .

as you see it's not an easy job , that's why people normaly run the rally cam with stock comp ratio

VERY usefull information! I'm going to adjust the head and I'll post a dyno run here afterwards. It's clear already that the last dyno run wasn't very good so I'm going to another dyno and start testing there!

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