JMP VF40

[SoobyDoobyDoo]

This is sort of a follow up to Tysparks’ JMP vf52 review, thought I’d just start a new thread rather than thread Jack the other one. I’ve got a spare VF40 core from DRdave a while back and was wanting to give it the JMP treatment, hopefully later in 2024 (we’ll see depending on how funds go). My question is for those who have it, can you give some details if it’s behavior (ie, spool, rom range, etc). Also, how does it respond to ots maps? I’d much rather have a pro tune but I may delay that so I have enough funds for a short block prior to doing that (just to be on the safe side). Just trying to explore options and do some research. Thanks in advance!

[KZJonny]

Everything about it is good, as long as you want to stay in the "small and snappy" turbo range.

- spool is faster for sure, like a couple hundred RPM
- it pulls harder and longer than stock, like nearly to redline, or at least it doesn't give up quite as much at 5.5k RPM (I tend to downshift around there anyway to get back into a good torque range, since I don't do any track stuff.)
- I have mine on a COBB STG 2 Map w/ EL Header + Catless UP and Grimmspeed catted DP + full catback / no problems with boost spiking incontrollably, tho I do plan on a protune at some point in the very near future + 3 port EBC, just to get everything working together as well as possible. (Also a GS top mount....)

I don't see needing a new short block to accomodate the upgraded turbo, nor should you need fuel injectors, tho I did install a new AEM pump + wiring + Sti pump controller, just to make the most of the stock side feeds.... Unless yours is aready showing it's age, or you are burning more oil than normal? Maybe a set of head studs wouldn't be a bad idea if you really want to turn up the wick. I am pretty sure I will have to do that upgrade soon, since 16.5-17psi peak boost seems to be lifting my heads a tiny bit. Still digging into that.

Looks stock because it is a stock frame. Sneaky, sneaky...

[SoobyDoobyDoo]

Thanks @KZJonny just looking for a basic upgrade, that’s it. I’ve heard about the improved oiling so that’s a def plus. I’m about 45k on a stock block, will probably keep stock boost levels as well. I’d just like to have funds available for a new short block in case…you never know. But I’ll probably get newer injectors and new fuel pump and the sti controller like you did cause mine are all original (cars got ~91k original miles on it, going on 19 yrs). Would just like to have new items to replace the originals. Thankfully doesn’t really burn any oil…I’ve only had to top it off a handful of times in the three years I’ve owned it. 3k oci too since rebuild. Goal is to ultimately keep it fun and reliable. Whatever power I can get out of it with new injectors and the turbo I’ll be happy with, not looking to make crazy stupid power as it’s my daily. Plus I’ve got an auto, so will be looking to do hexmods valve body upgrade with shift kit…would like to tune the TCU too cause I’ve got paddle shifters and I’d like the shifts to be a little quicker in sport mode. 

[KZJonny]

58 minutes ago, SoobyDoobyDoo said:

But I’ll probably get newer injectors

Do your own research of course, but using anything but stock injectors will take using any OTS tune off the table. You'd need to go in for a tune on a dyno, or install a wideband and video the AFR at the same time you are doing pulls for logs. Not a small job, and with the custom VF40 you should still be within safe limits on the 550cc stock yellow tops. This is quoting what I was told by Dave at Cryotune. So.... take that for what it's worth. Get a spare set and have them cleaned and flow tested. There really isn't much in a fuel injector to fail, really, not that they can't.

Even an e-tune or dyno tune on stock injectors doesn't require having/installing a wideband, so again, just something to think about.

 

I sort of suspect that if you are really just looking for 'daily driver' upgrades, you will be plenty happy with the uprated VF40 and stockish fueling. I am asking a little more from my car that it sounds like you are, so you really may not need all of that, but on the other hand a pump is cheap and I think I got my STi FPC for like $50 CAD... so, all of those things are sound investments.

[SoobyDoobyDoo]

Thanks for the feedback and also the bit about the injectors. I'll stay with stock then-I wasn’t planning on going super crazy but figured maybe something with a little more flow in case I ever wanted to do more in the future. Honestly stock would be fine for what I’d like to do. I figured the ots tune duty cycle would account for the flow but glad I learned something. I was wanting to install a wide band just to keep an eye on things (also planning on installing an oil temp/pressure gauge as well) just for monitoring purposes…but that’s further down the road. Appreciate the feedback about the turbo and what it did for you as well, hopefully at some point I can do a dyno tune with someone close by or an e-tune with one of the tuners on here.