Opel GT Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
Hello to all!
i have read here many articles about turbo conversion, but i still have some questions.
Aim is about 170-200kw from the engine. I have 2.2 block (also 1.9 and 2.0 engines)
question is what upgrade internals should i use, i have read all about chevy pistons and ford 2.3 rods
but maybe i can go straight to H beam rods and some good forged pistons.
As for the cam i have Enem X1 at the moment wich should work. there will be intercooler and
management will be Meqasquirt 3. I have a 6cyl cut intake with custom fuel rail.
For the drivetrain i will be using getrag 265 and rear will get either Gripper or Quaife LSD.
Should i go for bigger valves and porting the head?
I read RallyBobs setup for turbo cih, but because im not in US it might be better to get some other
pistons and rods.

Harri
 

·
Opel Rallier since 1977
Joined
·
2,127 Posts
I hope these comments will have some value to your project.

Bigger valves and porting are often not needed, but for that power level, which is up around 1.8 or 1.9 HP per cubic inch, you may well need that. I'd try it with just boost initially and see how much you get. For information, I am getting 1.75 HP per cubic inch with 47 mm intake and 40 mm exhaust valves with 14-15 psi boost on a Mitsubishi Starion 2.6L turbo engine, with the stock (large) intercooler, and 2.5" exhaust.

As for the X1 cam, I am not convinced that is the right cam. Turbo cams typically have wider lobe separation angle (LSA) and limited duration. If you have too much overlap (cused by too much duration and too small of an LSA), then you loose a lot of your intake charge; it just blows straight through from the intake to exhaust during the cam overlap. The turbo and exhaust get red hot with just normal running when that happens.

Again as an example, the stock Mitsubishi Starion 2.6L turbo has a 264 duration cam for intake and exhaust, with an LSA of 110 degrees which works out to 45 degrees of valve overlap. That cam produces 1.35 HP per cubic inch in stock form and 11-12 psi boost, with the stock (large) intercooler.

The Enem X1 cam has a 284 duration so with a 109 LSA, that is 65 degrees of overlap. The actual value of the X1 LSA is not clear to me; the Enem site lists it as 109 in 1 place and 107 in another place! If it is actually 107, then the overlap increases to around 70 degrees. So research cam overlap for turbo cams before you get too far.

An exhaust size of at least 2.5" with no muffler ought to be used.

And yes to the stronger rods and pistons! You are trying to push the engine pretty hard. I have run that 1.75 HP per cubic inch on the Starion engine with both hypereutectic and forged pistons. I also increased the static compression ratio from the factor 7.4 to a true 8.2:1. That made a huge difference in low RPM engine and boost response, which is of great value in a rally car engine. It wants to knock at around 16-17psi with premium fuel, so you may have to go a little lower on the static CR.

With your electronic control, I would want to have a knock sensor in the system and try to add in some knock control to try to avoid damage. I think your boost is going to be in the 15-20 psi range to achieve that level of HP, and that is a pretty high boost on gasoline. And I would think intercooling is manadatory for that level of performance.

What turbo family are you thinking of using? And is this for racing only, or for street driving too? If street driving, then you will probably care more about low RPM boost response and torque than if you are racing.

Sounds like fun!
 

·
Registered
Joined
·
802 Posts
The 22E pistons are not durable enough for a 200kW turbo build and neither are the cast rods. Which head are you planning to use ? A P22E head has stainless exhaust seat inserts that might be an advantage, just as the 45/40 valves. The Enem I10 turbo with 280° duration and 10,9mm lift has a 114° LSA. Another alternative could be the Y12/P13 profile with a 288° duration and 11,1mm lift and with a 112° LSA.
 

·
Super Moderator
Joined
·
13,686 Posts
I agree the 2.2 head is a better choice. It has a higher intake-to-exhaust flow ratio.
 
1 - 5 of 5 Posts
Top