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Xu9J2 Compression


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24 replies to this topic

#21
Thijs_Rallye

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I've never turbo'ed a XU9, so I don't know and above that it is not my decision to take ;).

 

Newer engines run a CR of 10 and above with a turbocharger, but back in the old days they were more around 8 / 8,8 ish.

 

it's up to you, try reading a book like Maximum boost by Corky Bell.



#22
mostormxu9

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Nobody turbo'ed a xu9 here?

Xu10j2te turbocharger is suitable?

How much boost is safe for this CR?



#23
B1ack_Mi16

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I run 9.2:1 on my 2.2 16v T16 engine.

 

But I have a big turbo so don't get boost till 3000-3500rpm ish.

I have max boost of 1.4 bar this far at 6200rpm and haven't seen any knock tendencies yet.

 

However if you add a lot of boost low down in the rev-range I think it might be applicable to knock easier at lower revs.

But you can run a fair bit of boost at 9.2:1 indeed I'm sure you can add 1 bar quite easily with correct fuelling and ignition.



#24
wicked

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In the end it's about the dynamic compression; that is a function of static compression, valve timing, boost....  

The common way is to trade static compression for boost to keep the same dynamic compression. Modern engines also use the valve timing to keep higher static compression off-boost. 

 

One limit for your dynamic compression is that it will start to knock if you go too high. But that level will differ per engine. If you have a lot of back pressure from your manifold/turbo it will knock sooner that a high end manifold with big turbo.

 

The xu10j2te turbo is suitable and has been used before. It's not suited for really high boost/big bhp numbers but it is an easy conversion. 

I would just try it.

Note that the turbo technics conversion for the 1.9 had a compression of 1:8.6 so you're not so far off.. 


Edited by wicked, 28 August 2017 - 10:38 AM.


#25
mostormxu9

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Thanks my friends.

In fact I dont want to give the engine high boost.

The safe range and 24/7 using is more important for me than achieving bhp.(using it all days)

I think about 9 psi almost.

You said an important topic.

Can I use Mi1.9 fuel injector for this boost?(216cc at 3 bar) I can use 3,5 bar regulator also.

Also buying a xu10j2te turbo and exhaust manifold is easiest way for me.

If i can achieve 160 bhp is  ideal for me.