Can anyone tell me if the huge power difference between my Euro M28/22 (310hp) motor and the US M28/20 (235hp) motor is because of the different compression ratio or are the heads different or other?

Sorry to be a bother , I have asked this on my other post , but I am running out of time on the option to purchase a complete US motor as opposed to only the cam for my Euro motor and need all the help I can get.

Thanks guys.

 

simple..... bigger vavle heads, bigger runners , huge throttle body, higher compression, much better cams. not to mention the less restrictive LHjet mass flow sensor vs the little 1.5x 2" Ljet AFM

 

So there is no way that I can use the heads or at least cams on my Euro motor ?

 

what is the best way to squeak more ponies out of a us? are euro parts interchangeable?

 

You can use US cams and heads, but you will loose hp.

 

I don't understand your question Andrew. Do you have a Euro engine with a bad cam? I'd just replace the cam if you can find one.

The heads/cams are responsible for the majority of the power difference.

 

Which I most definitely do not want to do, hence all the questions.

 

I bought the car with a broken cam and the only place I can find a replacement (used) is from the US and I am in South Africa.

I can however get a complete US spec motor here (ironic hey) for a not much more than the cost of the cam.

So I wanted to try and make sure that there was no possible way that I could use the US spec motor without losing 60 odd horses.

Someone mentioned to me that they knew the history of the car that I bought and it had overheating issues , which he suspects that they machined the heads incorrectly which might be causing the cam to break, if that makes any sense ?

It is becoming more and more apparent that I will have to go the route of getting the cam , but now I have the added worry about there being a fault on the head due to the previous 2 owners both having to replace the camshaft.

 

if you are really worried, pull the motor and pull the heads and machine them. probably not the issue. i would just put the new cam on, that might have been damaged as GB has said and be done with it. again, a US spec motor is a huge difference . (everything on the top of the block! and yes, its all interchangeable for the most part)

 

Second day I had the car I already pulled the motor to make life easier and to check everything.




I am going to stop beating myself up about this and simply spend the money on the cam and rebuild.
Still have to check if I have any bent valves.
Any ideas on how to do that without removing the heads ??

 

Good luck.

 

Gotta love RL on your phone.

 

Without being able to spin the engine, I don't know of a way to check for bent valves. You can't do a compression test like it sits.

If the engine is already out it's not a big deal to pull the valves. However, if you have bent valves, I would expect to see witness marks in the top of the piston as well.

 

Check for bent valves with a leakdown test. The test puts air pressure in the cylider with piston at TDC on the compression stroke. The 'leakdown' test is a flow measurement through a precision orifice, with pressure upstream and downstream of the orifice used to figure out how much air passes through bent valves and/or leaking rings.

For just a simple test go/no go on valve leakage, you can put each cylinder at TDC and put air pressure on them. It doesn't take much, and you really don't want a lot since you risk the air spinning the engine. Test is usually done with 100 PSI to make the flow test easy, less needed to just listem to the exhaust and intake for leaking air through a bent valve.

 

Thanks for the advice guys.

Very much appreciated.

Hopefully one day when all is said and done, I can also be a 928 expert !