head rebuild for turbo

[DrMcDave]

alright for some reason i didn't get much help on e30tech

I am rebuilding my head for boost. its going to be NA for a while because this is an expensive undertaking on my part. I am getting PPF rockers and thats all that set in stone at this point.

I need everything else to be able to hit 8k. I do realize the bottom end cannot handle this but i will upgrade that at a later date when i have more $$$ and time.

so i need probably valves that can handle that.
a cam
and whatever springs and retainers.

what should i get and where can i get it. I thank my tax return for part of this project.

[AndrewBird]

Talk to Matt:

http://www.r3vlimited.com/board/member.php?u=7516

He has a stroker turbo and has rebuilt it and then some.

[nando]

8k rpm? Now we know a stock cam won't be good for that, but big cams are generally not used for turbos. many people do use the 272 though, and I think mr325 might be using a 288.

definitely get the HD valve springs, and titanium retainers would be a good idea too. I wouldn't port it very much, I think you'd run the risk of cracking with boost (it takes quite a bit of material removal to port match the exhaust for example). A light porting job would probably be fine, just enough to smooth out the flow, and polish the exhaust ports only.

I think the stock valves will be fine, but I don't know.. not many people have built 8k rpm M20s ;)

I'm sticking to 6900 N/A!

[DrMcDave]

8k rpm? Now we know a stock cam won't be good for that, but big cams are generally not used for turbos. many people do use the 272 though, and I think mr325 might be using a 288.

definitely get the HD valve springs, and titanium retainers would be a good idea too. I wouldn't port it very much, I think you'd run the risk of cracking with boost (it takes quite a bit of material removal to port match the exhaust for example). A light porting job would probably be fine, just enough to smooth out the flow, and polish the exhaust ports only.

I think the stock valves will be fine, but I don't know.. not many people have built 8k rpm M20s ;)

I'm sticking to 6900 N/A!

i thought about it, but 6900 comes fast w/ 3.91 gearing. I do want that euro gearing. I'm not even sure i am going to run to 8k but i want to be able to. Yeah obviously the stock cam falls on its face at like 5800 or something.
I guess i am most worried about the valves. Will the stock valves go to 8k.

[matt325is]

The valves should be fine, the valve springs need to be stiffer, to prevent valve float. Titanium retainers should only be used on race cars, they wear out faster, and are meant to be taken out after a season. I would suggest a custom PPF turbo cam, around 276 or 288 would be good if you want high rpm, you will also want to consider a split pulse manifold if you want good high end power with that cam, the more flow, the better. 8k will also need a pretty big turbo, if you look at the Swedes, they have huge holsets or precision turbo's as they rev high, they flow more air.

If you get the ppf rockers and stiff valve springs, you should be set. I wouldnt worry too much about porting, I port matched my exhaust side, and it'll be fine, there is still a bunch of material left. Make sure to replace your guides and stem seals at the same time.

Here are the pics of my head rebuild: http://www.mkosonen.com/headrebuild

I'd also recommend the MLS steel head gasket, and a resurface of the head for a perfect seal.

matt

[DrMcDave]

The valves should be fine, the valve springs need to be stiffer, to prevent valve float. Titanium retainers should only be used on race cars, they wear out faster, and are meant to be taken out after a season. I would suggest a custom PPF turbo cam, around 276 or 288 would be good if you want high rpm, you will also want to consider a split pulse manifold if you want good high end power with that cam, the more flow, the better. 8k will also need a pretty big turbo, if you look at the Swedes, they have huge holsets or precision turbo's as they rev high, they flow more air.

If you get the ppf rockers and stiff valve springs, you should be set. I wouldnt worry too much about porting, I port matched my exhaust side, and it'll be fine, there is still a bunch of material left. Make sure to replace your guides and stem seals at the same time.

Here are the pics of my head rebuild: http://www.mkosonen.com/headrebuild

I'd also recommend the MLS steel head gasket, and a resurface of the head for a perfect seal.

matt

awesome so it won't be an ungoldy expensive build.

[JRowe]

Before you shoot for 8k, you need to give some serious thought to what you ultimately want the motor to become. Start out with a HP figure in mind and balance that with how driveable you want the engine. If you are going 8k with a turbo, that automatically means almost no bottom and a big turbo that will offer little transition between boost and no boost.

Once you know what power you are shooting for, it will determine your turbo size. Go with the smallest that will give you the desired power. Less lag and transition between na and boost. It will also make it more driveable. Now, you've probably already considered these things and plan on having little day to day driveability and gobs of power. Otherwise, there is no need for a 8k redline and big turbo.

Personally, someday I'd like to go the turbo route also. I'd like to hit 10-12 psi of boost with a relatively small turbo mated to a "2.7i" engine. It's a good compromise between power and driveability. With proper tuning, you can see 250+ hp at the wheels. More than enough for the street.

Just my $.02.

[DrMcDave]

Before you shoot for 8k, you need to give some serious thought to what you ultimately want the motor to become. Start out with a HP figure in mind and balance that with how driveable you want the engine. If you are going 8k with a turbo, that automatically means almost no bottom and a big turbo that will offer little transition between boost and no boost.

Once you know what power you are shooting for, it will determine your turbo size. Go with the smallest that will give you the desired power. Less lag and transition between na and boost. It will also make it more driveable. Now, you've probably already considered these things and plan on having little day to day driveability and gobs of power. Otherwise, there is no need for a 8k redline and big turbo.

Personally, someday I'd like to go the turbo route also. I'd like to hit 10-12 psi of boost with a relatively small turbo mated to a "2.7i" engine. It's a good compromise between power and driveability. With proper tuning, you can see 250+ hp at the wheels. More than enough for the street.

Just my $.02.

well, i am not looking for huge hp for one. The 8k rpm will help the short gearing of the ix. I am okay w/ it making more power up high because of the transfer case and applying a huge amount of torque right away. I am still in the early stages. I think its going to have the ability to hit 8k but i don't know how much i'll go that high. Atleast not without a lower end rebuild before i try.

i appreciate the opinions guys keep them coming.

[nando]

alex has a set of euro 3.64s he's willing to sell. I don't think an 8k M20 would be very fun or reliable, especially on the street. and with an ix you really need that bottom end to get the car moving..

[DrMcDave]

alex has a set of euro 3.64s he's willing to sell. I don't think an 8k M20 would be very fun or reliable, especially on the street. and with an ix you really need that bottom end to get the car moving..

i've got a line on a just rebuild head so i might get that instead.

[diegom6]

Try to weld the water chanels and if you aren't going to get a MLS HG, do the oring job to prevent a blown head gasket.

here are some pics I took of my car, maybe can give you a idea...

http://http://www.e30tech.com/forum/viewtopic.php?t=23616

http://www.e30tech.com/forum/viewtopic.php?t=22427&start=0

[nando]

I would have them welded anyway, M20 heads seem like they crack pretty easily.

[diegom6]

I would have them welded anyway, M20 heads seem like they crack pretty easily.

M50'S cracks easier IMO

[sweetride01]

Is it ok to keep the engine 2.5 and turbo it?
I figured that a built S52 install would cost me $9K+, and that's not happening any time soon.
So, if I do spend money on rebuilding my head and current engine, I would like to do it with a turbo in mind. As far as hp, I'd look for 280-350hp at the crank.
Right now, I'm looking at $3500 for a redone head with rockers, 288 cam, p/p and valve springs. So, how much more would I have to spend to get the head turbo-ready? How would a GT28-35 turbo work in the M20?
How much bottom end am I gonna have to replace - just new pistons and rods?
What is involved in welding the water channels?

Sorry to (kind of) hijack the thread.

[diegom6]

Is it ok to keep the engine 2.5 and turbo it?
I figured that a built S52 install would cost me $9K+, and that's not happening any time soon.
So, if I do spend money on rebuilding my head and current engine, I would like to do it with a turbo in mind. As far as hp, I'd look for 280-350hp at the crank.
Right now, I'm looking at $3500 for a redone head with rockers, 288 cam, p/p and valve springs. So, how much more would I have to spend to get the head turbo-ready? How would a GT28-35 turbo work in the M20?
How much bottom end am I gonna have to replace - just new pistons and rods?
What is involved in welding the water channels?

Sorry to (kind of) hijack the thread.

You don't need exactly those items to run 350 HP crank...a stock m20b25 well maintened and no tmuch miles o nit will do the job witht he help of a standalone system for at least the fuel delivery.

A 288 cam would be nice but I think is not worth in you are going to use a such small turbo with probably 524td manifold, but if is a adaptor, better! Hotter cams doesn't like too much flow restriction, = backpressure! for turbo application.

PPF rockers/valves springs aren't needed as well for this HP goal, but if you have the money to spend on it, why not!?:p