Compression difference between USDM and JDM VVT motors?
 

Looking for a new motor for my rotrex'd VVT swapped 90. I was on the hunt for a bp4w as they are around here in Florida and a lot of the guys recommend them. Searching the threads, it's recommend for the slightly lower compression for rotrex boost.

There's also a couple VVTs, including an imported low miles JDM motor. Days of searching I'm getting conflicting info that the JDM BPZE/BP6D is 10.5:1 and the USDM is 10 1. Can anyone confirm or deny?

If I'm strictly 93 pump gas, is 10:1 compression fine for 230ish whp for track, autox, street car? If the JDM is 10.5:1, is that safe or getting out of hand?

Thanks.

I have a set of JDM VVT pistons.
Can confirm they are 10.5.

The 10.5 motor won't be any weaker. Just may require a different tune. It can safely do 230whp just as well as the 10:1 motor can.

I wouldn't pay extra for one. I wouldn't pay less for one, either.

Thanks, did you order them or found used?

It's already a pretty good deal AND comes with a square top and warranty for $999.

rotrex doesn't make torque. you're totally fine with the higher compression

Sounds like a no-brainer.

Thanks for the input guys.

Can you please post pictures of the pistons? I purchased a JDM motor a while back and I would like know if this motor has the same pistons as yours.

This is what my broken 10.5:1 JDM pistons looked like.

https://farm5.staticflickr.com/4295/...dc822e32_b.jpg
https://farm5.staticflickr.com/4315/...99d080f1_b.jpg
https://farm5.staticflickr.com/4314/...4485778e_b.jpg

That looks a lot like a standard VVT piston.

Stock USDM 01-05 pistons do not have that third step-up in the center.

Brought the pictures up on an actual computer with a real screen not an iPhone and I see the difference now. Thanks.

/\ very helpful, thanks

Yes, very helpful!

Placed the order for the JDM VVT with square top motor yesterday, hopefully it's not shit.

Interesting that they dropped the dome away from the spark plug in the center of the 10.5:1 slug.

Those are great photographs, thankyou.