Is it necessary to have a closed deck to get high numbers? I've been thinking of going with a single turbo setup instead but 800+ would still be the goal.

To the OP you have a very legitimate question and we have a lot of customers ask this question. Since you decided on a 4.0L we can give you an example of what our newest build is:

Bullitt5897's 4.0L closed deck motor

Bryant racing billet 4.0L crank
LA Sleeves
Carillo rods
CP 96mm pistons
Race bearings
Oil pump gear upgrade

Now here is the explanation of the parts and why:
Bryant racing cranks are the absolute best cranks on the market! Perfectly balanced and bulletproof!
LA Sleeves are also another point of strength. Coupled with a closed deck collar the sleeves give the cylinder the rigidity it needs for high boost applications.
Carrillo rods and cp Pistons are the best in the industry and you just can't beat them.
The upgraded oil pump gears are crucial to the longevity of the oiling system and will ensure the oil pump stays pumping up to super high rpms!

So OP to answer your question:
We would recommend closed deck blocks for all of our customers. They work very well and many of our new high horsepower clients are making the switch. Sleeving the cylinders will make sure that your cylinders can take a beating in the worse case scenarios and still have a salvageable motor. For anyone pushing the limits we recommend sleeving the motors. Sleeves cost about $600 and is a great insurance policy to save your block.

If you would like a personal quote or just want a more personal answer based on your build send us a pm and we will be more than happy to guide you in the right direction so that you only have to do this once.


- The RJ MFG team

No a closed deck is not needed but it gives the cylinder walls extra rigidity at the top where you see the most force due to the stroker cranks and larger bore Pistons. Think of it as an insurance policy for your cylinders. We are big advocates of proven technology and that's what we bring to the market. From our oil pump gears, GTR intake conversions and closed deck blocks all proven to work and be reliable.

Abec, glad to hear you made a choice, I barely keep the engine build thread up to date as many of the manufacturer for parts do not directly list parts for the VQ37 on their website. Typically I have seen VQ35 but no mention of the 3.7 engine which makes it difficult to know if they support our engine or not.

I will say, it seems some known and new companies are producing parts so it might be a time to re-build the sticky.