decomp plate comp rattios on late spec m20b25

[midnight]

basically im gonna be strapping a big silly turbo on my face lift 2.5 and was wondering what the comp ratios would be reduced to with a decompression plate and what safe limits of boost would be also???????

[Colonel Sanders]

i have an mls for sale .120 takes the cr down to 8.0 for sale, i have fitted it but the car has never been run. just opted to rebuild the full motor with low comp pistons so have no need for the gasket

[march109]

i have an mls for sale .120 takes the cr down to 8.0 for sale, i have fitted it but the car has never been run. just opted to rebuild the full motor with low comp pistons so have no need for the gasket

That really depends on if the block has been decked before. CR depends on stroke, bore and combustion chamber volume (assuming you include headgasket volume ect..)

It will certainly reduce CR though and allow you to run more boost than stock..

[fowler]

Jesus Kev you can chuck a bar down that engine without pissing about with decomp plates and stuff
whats the point just get manifold and turbo job done of course oil feeds etc .
Regards
Ben

[midnight]

actually i spoke to antoine and hes got an mls so will slap it on, cheers for the offer rossle, and ben my old car shit to many gaskets so not taking chances this time, i want plenty boost too

[Turbo-Brown]

Wonder if the old setup popped gaskets because of the little hotside (assuming you're talking about the turbo in your sig there?) Just a thought really.

[maxfield]

If you want to run silly boost, shouldn't you be thinking about low comp pistons rather than a decomp plate?

[Turbo-Brown]

You'll probably find more power using a big turbo and the same boost you used to have, so having the silly big turbo doesn't necessarily mean silly big boost.

All the same, if it were me I'd use low comp pistons.

[march109]

You'll probably find more power using a big turbo and the same boost you used to have, so having the silly big turbo doesn't necessarily mean silly big boost.

All the same, if it were me I'd use low comp pistons.

For the price paid for custom pistons a decomp place just seems a waste, especially when you consider its really another weak spot.

How many mm thick does the decomp plate need to be to drop the CR by a factor of 1 on an M20?

[midnight]

well im not using the cossie turbo in my sig, that blew up when it was on my fietsa, yeah it was quite a punie hot side on that one the new one im going i think is called a holset hx355, not sure think its similar to the hx40, well not massive boost obviously, but on my old one died on 12psi, im looking at about 1.4bar, which should be sufficient with the large hot side and the mls gasket and compression of roughly 8.1-1. i am thinking about fukll steel internals with low comp pistons, but dont really want the cost of building it to spiral out of control at the mo

[Colonel Sanders]

nor did i mate but im 8k into mine now since i bought that stuff from you....

[midnight]

bloody hell sean u must be on some serious mission mate, what turbo did u use then?

[Colonel Sanders]

its a holset hybrid, will be good for around 600hp, im aiming for around 450, 500hp?
one thing led to another and it just never ends!!!lol
but it will be worth it in the end....

[midnight]

hell yeah thats what im getting this time too some comedy sized holset, the only thing is every time u make it faster something else brakes..........

[Colonel Sanders]

thats whay ive uprated everything, including suspension, driveline and brakes. thats why its cost so much, the car could prob handle anything i can throw at it. but im sure it still wont be smooth for a while, there are always bits that need tweaking with a new build.
so what are you looking at doin now then?

[midnight]

well imk gonna get this turbo build done on the new e30, and see how it holds up, and bit burther down the line maybe go full steel bottom end etc with the m20 or go full out on an m50 engine

[Karan]

id just invest in some forged pistons and maybe rods, decomp plate/thick h/gs just seem like temporary bodges to me

[Colonel Sanders]

well imk gonna get this turbo build done on the new e30, and see how it holds up, and bit burther down the line maybe go full steel bottom end etc with the m20 or go full out on an m50 engine

i thought about an m50 motor, but i have a love for the m20 motor, potential for well over 1000hp, and cheap an easy to build..

[Karan]

well imk gonna get this turbo build done on the new e30, and see how it holds up, and bit burther down the line maybe go full steel bottom end etc with the m20 or go full out on an m50 engine

i thought about an m50 motor, but i have a love for the m20 motor, potential for well over 1000hp, and cheap an easy to build..

surely there arent any 1000bhp m20s out there?

[Colonel Sanders]

limmet had around 1200hp from his m20, il see if i can hook the video out.
alot of people think the m20 aint a very good engine for power but they take to turbos really well.

[Turbo-Brown]

Thought Limmet's 1200bhp car has an S50B32 in it?

Do vaguely recall an M20 with about 800bhp which might also have belonged to him.

[midnight]

yeah thats what i was thinking but its just the m50 breathes so much better being a 4 v per cylinder engine

[Karan]

Thought Limmet's 1200bhp car has an S50B32 in it?

Do vaguely recall an M20 with about 800bhp which might also have belonged to him.

i may take my s38 apart and get some pistons and rods in there and go for some big power after i have built an engine for my silvia

[Turbo-Brown]

I imagine it's cheaper to build an S38 with modified parts than standard thinking about it. £600 for pistons and about £300 for rods and you're a good part of the way there!

[Colonel Sanders]

Thought Limmet's 1200bhp car has an S50B32 in it?

Do vaguely recall an M20 with about 800bhp which might also have belonged to him.

he had m20s too, found the vid, enjoy...
http://www.miloop.se/film_view.aspx?movie=7550

[Colonel Sanders]

and another
http://www.miloop.se/film_view.aspx?mm=5&movie=5726

[Karan]

omg i just creamed myself! what a perrrrrrrrrrrfect car

[Colonel Sanders]

tis very sexy!! the m20 can be pushed very far...

[Turbo-Brown]

Crikey! Budget build though?

[Colonel Sanders]

haha yeah, cos its an m20. thats why i see no need to leave my love of m20s..

[Colonel Sanders]

speaking of wich, his old motor is for sale now....
http://www.pure-pf.com/phpBB2/viewtopic.php?t=19611

[midnight]

hell yeah