200 Crossflow Turbo Head Porting

[XPT 673]

For all of the crossflow experts in here. When I eventually rebuild my motor, it will be a 200 injected turbo.

Everyone here goes into detail on porting mostly for N/A 250 xflows for obvious reasons.

I have an unmarked XE carby head (from a 250) which I'll be using. My question is do I bother with porting and larger inlet valves or will that make it doughy off boost being a 200? Or should I just do a basic cleanup of the ports with standard sized valves?

Also I planned on using something like a Dynotec "stage 2" cam (exact specs unsure) thinking that a mildish cam on a 250 would be a bit wilder on a 200. The car will be manual with pretty large turbo so off boost performance is important.

[slydog 7,873]

Well I will be interested in this as well but I would deffinatly look at a custom camshaft for it with wide lobe sep and some lift.Duration isn't needed on a boosted engine but lift and a wide lobe sep helps.The camshaft will only tell the engine WHEN it is going to make it's power and how much to a degree but you don't want close enough you want right so off the shelf is not wanted here.

 

As for the head lets wait and see but you would assume been boosted it will be a case of the turbine will push it in no matter what and tune to suit.That said a bigger inlet and a worked exhaust port as you need exhaust flow to move the turbo could only help here IMO but most likely wrong...LOL     

[ando76 4,354]

Anything you can do to promote flow in any application is a good thing.  More air/fuel in makes for more power, especially when the cam is set to take advantage of it. 

 

It really depends on what you are chasing with the package.  being a 200/ 200 motor it will love to rev and that is a good thing with the boost.  I would suggest an EF crank in there as well to help smooth harmonics tho. 

 

An off the shelf grind may be suitable in a moderate power level, basic set up but really I would be talking to any of the local cam grinders and coming up with something to suit your application. 

 

Obviously BA turbo motors perform very well and I think this is in part due to their better flowing cylinder heads, so a tickle up of your XE head can not hurt performance. 

 

I guess what I am trying to get at is you need to work out what power level you are aiming at, and probably add another 100hp as boost becomes addictive (from everything I have read) and design the package around that application. 

 

In a light xp ute any power you generate will be good fun.  I am aiming for 450@ the wheels for my XM turbo project and I have a ported E2 head here that runs some good numbers.  Ray HALL up here, who is a well renowned turbo man, told be he made over 550 at the wheels from a turbo x-flow in the early 90's.  smart man.  It had a good cylinder head and great tune so I guess the two go hand in hand. 

[XPT 673]

Thanks for the responses guys,

Sly I know what you are saying about cam selection, and from what I understand you don't want too much overlap with a turbo motor. I guess it's all a balancing act. If the ports are too big coupled being 200ci with around 8.5:1 compression and a large turbo (MP T70) it will be a dog off boost. If ports/valves are too small you restrict top end power. This is a grose simplification of course.

 

Ando I hear you with the 4litre EF fully counter weighted crank only problem is it will become a 250 again due to the stroke. The last time I read the RTA rules my car can only be 3 times it's weight in capacity with forced induction. 1170 x 3 = 3510cc maximum capacity that's the reason for going with the 200. Otherwise the extra 50 cubes would be great!

 

I will probably talk to someone like Wade or Camtech for their recommendations if you guys think there isn't an off the shelf mild cam suitable. I'm not going to be running massive boost (1.2 bar max) due to the fact that I'll only be using prepped 200 rods and probably hypatec pistons. Looking at the compressor map my turbo can pump a theoretical 450-500 hp worth of air at 1 bar so if I can make everything work as efficiently as possible hopefully it can make good power.

 

As for power levels I want enough power that the car is fun to drive without doing a 360 every time I put the boot in. So I'm guessing maybe 350-400rwhp. If It did anywhere in the 11's I'd be chuffed.

[gerg 10,871]

I reckon a tidy-up of the throat and de-dag of the rest of the port is as far as you should go. Maybe a port-match (can't hurt) Otherwise it will, like you say, be a slug until the turbo comes on. Remember you don't have nice, long runners in your inlet to help with port tuning. Air velocity is the key, so port size needs to be as small as possible, particularly if the engine is 20% smaller than what all the bits were intended for.

 

I'd keep the valves stock size too. I reckon the exhaust port could cop a bit more work as I reckon it needs it. Don't bother with 3-angle valve cuts, etc, especially on the exhaust. You need all the surface area in the seat that you can get to transfer heat out of the valve.

 

Camshafts, I'd go with a towing cam. They come in at about 1800 on a 250 so a 200 might be at 2100 or so. It actually had a towing cam in it (FYI everyone: this donk used to be mine) and that was very torquey if you can remember.

[ando76 4,354]

200 - 250 how are they going to tell when you have the sump on.  rules were meant to be broken. LOL.

[XPT 673]

I don't know any engineers, but I'm sure they'd want some proof of the capacity and that "nah mate she's a 200" wouldn't be enough. I'd just hate to get to that point and get knocked back. Besides all that it's a bit different. Ando how did you plan on getting your XM engineered ?

[slydog 7,873]

200 turbo cubes right here...

 

[XPT 673]

Yep, Joe Gauci's Corty. What a weapon, I think it's a twin turbo V8 nowadays.

[ando76 4,354]

Read post 6. lol

[Clevo120Y 815]

Cylinder head wise I would be improving the exhaust side of things, not in size but around the bowl and short turn. I think the E2 has the largest stock exhaust valve from memory so that would be a good start plus it has a large open chamber to keep comp lower for boost. Intake port wise I would just be doing some work in the throat and short turn and leaving the main port runner size stock but just adding some texture on the walls.

[XPT 673]

Thanks mate, I will attempt to put all of that into practice. Mine is an unmarked XE carby head which I've read elsewhere is a decent head for turbocharging. I guess I will find out when I give it a go, thanks for the advice !

[Tyler06 266]

They go on the engine numbers to find out what literage it is so if you don't tell them they wont know its been changed.

[XPT 673]

 

They go on the engine numbers to find out what literage it is so if you don't tell them they wont know its been changed.

Only problem it's a 250 which I'm destroking to a 200. It will be something different anyway. Besides I get to put super pursuit 200 badges on !

[gerg 10,871]

I think 3.3 litres is still a decent size donk. Folks are getting stupid power out of RB26s so it can't be all bad. Ok they've got 72 over head cams, 21 turbos and 14 computers but it shows that cubes aren't everything.

[XPT 673]

I think 3.3 litres is still a decent size donk. Folks are getting stupid power out of RB26s so it can't be all bad. Ok they've got 72 over head cams, 21 turbos and 14 computers but it shows that cubes aren't everything.

Or a 2JZ for that matter, even though it's a Massey Ferguson to both by comparison I should be able to drag it kicking and screaming into being a half decent thing.