Bore out a VQ35HR

Kil'Jaden · 10-28-2009, 04:40 PM

What's the feasibility of boring the engine out to 3.8L? How much money so you think to do it along with all the internals? Durability?

Anybody done it/have an idea of what specific internal parts would work best?

I've spent a lot of time trying to find a thread on this with no luck, but I am sure this has come up before.

Z1 Performance · 10-28-2009, 08:07 PM

it will cost alot

durability? all depends who does your machining and assembly, and who does your tuning

who's done it on an HR? No one that I have seen. Several have done it on the DE, but the internals are different

archangel72 · 10-28-2009, 08:48 PM

What would be the benifits of boreing it out vs stroking it out? GTM has a 3.8L stroker kit for the hr.

Lakeside · 10-29-2009, 06:32 AM

A stroker adds more wear and tear. Pistons speeds are higher! We race stroked motors in the APBA and IJSBA aka jet ski racing and engines need to be torn down and rebuilt more often due to the wear on the two and four stroke engines.

The Torque is amazing! But do you have the cash to rebuild it if compression drops or a bearing fails?

Z1 Performance · 10-29-2009, 07:09 AM

Quote:

Originally Posted by Lakeside

A stroker adds more wear and tear. Pistons speeds are higher! We race stroked motors in the APBA and IJSBA aka jet ski racing and engines need to be torn down and rebuilt more often due to the wear on the two and four stroke engines.

The Torque is amazing! But do you have the cash to rebuild it if compression drops or a bearing fails?

If a bearing fails or compression drops on any motor, you run into the same problem

Piston speed will depend on the stroke of the crank, and the rpm range of the engine - faster piston speeds are not a given by any means. Typically strokers have a lower rpm range than non strokers

A well built motor will be able to cope with this better than a stock engine can, as the quality of the components can be better (and lighter in many cases), as well as the tolerences of the bearings. The success or failure is in the quality of the components and the skill level of the machinist

lee_dfw · 10-30-2009, 02:57 PM

Going from 3.5L to 3.8L with all stroke will increase max piston speed about 8% and max acceleration 9% using the same length rods. Those numbers go down if you increase rod length on the stroker.

Not sure how much that matters.

neverenough · 10-30-2009, 07:27 PM

There is a twin turbo 3.8 hr being built right now. GTM is doing the build for me. Don't want to say to much to soon but it is happening now. There will be a thread keeping track of the build soon.