Author Topic: Turbo Friendly? (Read 3861 times)

littleboyblues · « **on:** February 22, 2009, 07:04:38 PM »

Turbos generally like lowish compressions and the m42 has 10:1 which is kinda high. I know you can change the crank to lower the compression but i'm just wondering if m42's respond nicely to being turboed.

Thanks

JoeDellio · « **Reply #1 on:** February 22, 2009, 08:47:38 PM »

Quote from: littleboyblues;67031

Turbos generally like lowish compressions and the m42 has 10:1 which is kinda high. I know you can change the crank to lower the compression but i'm just wondering if m42's respond nicely to being turboed.

Thanks

I dont know what these engines can handle stock, but I can tell you I wouldnt want to find out, higher compression will yield more HP in the long run but wont be forgiving on the tune. You have to have a good tuner bottomline in any FI application to be reliable and make the most power out of what you got.

littleboyblues · « **Reply #2 on:** February 23, 2009, 02:57:06 PM »

wouldn't a FI tune be more difficult than a higher compression one?

Danny707 · « **Reply #3 on:** February 23, 2009, 03:43:52 PM »

An FI tune is harder on a higher compression motor.

littleboyblues · « **Reply #4 on:** February 23, 2009, 04:20:09 PM »

That makes sence that a higher compression FI would yeild more than a low compression one but would be harder to tune. So you would go with the lower compression. Doesnt this sort of take away its rev happiness b/c you are stroking it. I assume thats how most people get a lower compression.

bearsbmw · « **Reply #5 on:** February 23, 2009, 05:09:38 PM »

M42 are turbo friendly on stock interals up to 12 psi and m44 are friendly at 10psi... some choose to run slightly higher but I don't think it's a good idea

littleboyblues · « **Reply #6 on:** February 23, 2009, 05:18:37 PM »

Thanks. That clears things up a lot. I just sort of had this impression that everybody had to alter their compression inorder to turbo it. Guess not:)

Deyan · « **Reply #7 on:** February 24, 2009, 07:47:01 AM »

If you use higher octane fuel and I am not sure, but some colder sparking plugs, you could run on 10-12 psi. But at the end it depends how you tune your car (A/F mixure, ignition). A friend of mine run M40B16 on 12 psi without problems and the engine blew on 18-20 psi

and he told me, that 10 psi is like a friendly boost.