JHM stage 1 supercharger kit

[sakimano]

any update SAR?

[sar]

any update SAR?

nar nothing to report yet, my mechanic friend who is helping with the install is away on holiday. hes back next week so hopefully getting started then.

[sar]

Now I'm not hating (as I'm not in the market for a supercharger with new toy inbound), and am genuinely curious from my experience with the 211.
On the 211 the air comes in and goes through a long journey round the engine bay, through an air charge cooler and back into the intake manifold.
It's the chrome pipes in the pic above - the left pipe goes from charger to cooler (black) and then the right pipe goes from cooler to manifold.
The issue that I have found is that the large volume of air between charger and cylinders gives a degree of elasticity to the throttle response and also played havoc with random stalling if snapping the throttle shut. Managed to fix the stalling issue by tweaking the mapping but the throttle sensitivity was much trickier - required tuning to the acceleration of the throttle mapping (so going from 0-50% pedal travel would actually result in the throttle briefly going from 0% to 75% and then back to 50%.


Are JHM looking at a custom manifold? Might be a thought as I would guess the long bent intake trumpets of the OEM are not ideal (but still perfectly adequate) - the advantage here is that they could probably look at a smaller more direct manifold which could also give a larger clearance between the engine help with any heat (could fit spacers without bending fuel lines). Or is this where they are going to put the charge cooler?

How dare you! hater!



They are not changing the manifold. They've put about 30,000 miles supercharged on their stage 1 and then another 20,000 on their stage 2 setup on their in house car. They have ironed out any problems (but to my knowledge never experienced anything like you described)

I have driven them both (stage 1 and stage 2 intercooled) and found that they both basically drove like stock RS4s as far as 'driveability' goes...that ambiguous word again. No weird niggles or annoyances. It literally just pulls, and then pulls like a train up top. Where the all motor RS4 is a little flat up top, the centrifugal blower loves the revs and delivers plenty of air.

There are perhaps gains to be made with a custom manifold, but to be honest I don't think the cost of R&D (and then additional costs in the kit) were worth it. Thing about JHM is they own the cars they make parts for, and they tear them to pieces. Case in point, on the B67 S4, they reworked the internal structure of the intake manifold, and made about 15 whp doing so. On the Rs4, when they took the manifold appart, they found the intake manifold already excellently designed and didn't see any $/power gains worth doing. When they supercharged the car, they felt 'why reinvent the wheel' with respect to the already excellent intake manifold, and sought a different design to the normal blower-in-manifold design. I'd love to hear why TTS put their rotrex cfuge inside the manifold as opposed to going the way JHM did.

i have been in touch with kurt jhm's calibrator and he has confirmed that there is no issue with throttle response/lag/elasticity/stalling. like saki said they have been testing and tweaking this kit now for probably two years now on the rs4 and before that on the s4 so there has been plenty of time to iron out any quirks (if they were even there in the first place).

also jhm have no intention of developing a new manifold for the rs4, in fact they see it as a huge plus point to be able to keep the oem unit. they say the oem manifold is incredibly efficient and is capable of flowing a ton of air.
also they dont have to compromise on there cooling solution for stage 2, they are not trying to cram a supercharger, a new manifold and cooling into the v between cylinder banks.

[sar]

I run no cat d/ps and full milltek system so very free flowing,inlet manifold has had Mrc treatment too,so with this in mind what gains do you think this charger would add roughly,I have a new stock clutch fitted,would this be up to the job? I never launch the car as I have too much mechanical sympathy.The lag effect through long induction piping is a concern,what are your thoughts on it?

i run no cat jhm 2.75" d/ps and full jhm 2.75" catback, and also have mrc everything else, so in a similar situation to yourself. the gains i get from stage 1 are what ever they are but im expecting a decent bump, im really just using stage 1 as a stepping stone to stage 2 when its ready to launch.

That is pretty much how I was seeing it adsgreen,always accepted the system was purely for noise and worth every penny at that! I figured no cats must be of serious advantage in flow given there pretty restrictive,I would be very happy with anything close to 30% gains but if was a lot less given were I'm at already it might not be quite so attractive for me personally?it would be nice to see some Dyno plots to see torque delivery etc

a 30% gain for you would be 138hp, theoretically taking you to 598hp, thats more or less TTS numbers? i think thats wanting a bit much for a stage 1 kit thats half the price of the TTS kit.

[adsgreen]

I doubt (but happy to be corrected) that the setup above will get the same 30% bump as a stock oem engine. Most of the improvements to the NA won't be as relevant when you are shoving the air in under pressure.

[sar]

At last mate!!!! I can't wait to see it

yer took longer than expected to work through the differences between l/h/d and r/h/d. as soon as its done ill take you for a blast!

[adsgreen]

There are a lot of pro's to putting the charger in the V. Certainly a lot easier to map as you are controlling a relatively consistent amount of air with the throttle plate being in front of the charger. Compressor stall (granted, not as relevant with centrifugal) isn't a factor as you're not having compressed air slam against the throttle plate and head backwards through the charger.
There also is virtually no distance between charger source and cylinder helping throttle response again helping mapping.
Also I guess it is easier to mount firmly to the engine with out too many custom brackets.
downsides? obviously a heat source and packaging is a concern and it does limit the size of the charge cooler.
Oh, and cost obviously

I'm sure the standard manifold can flow a lot of air but it's just adding to the distance the compressed air has to travel (with the inverted U shaped trumpets). Is it worth changing? For stage 1 probably not give the cost per bang.

[sar]

I doubt (but happy to be corrected) that the setup above will get the same 30% bump as a stock oem engine. Most of the improvements to the NA won't be as relevant when you are shoving the air in under pressure.

i agree. a 30% bump to stock figures at 414 ish would be 124hp so about 538hp ish would be more realistic.
just to be clear jhm have never used the 30% figure im just using it because lengtster1 mentioned thats where he would see value for money.

[sar]

There are a lot of pro's to putting the charger in the V. Certainly a lot easier to map as you are controlling a relatively consistent amount of air with the throttle plate being in front of the charger. Compressor stall (granted, not as relevant with centrifugal) isn't a factor as you're not having compressed air slam against the throttle plate and head backwards through the charger.
There also is virtually no distance between charger source and cylinder helping throttle response again helping mapping.
Also I guess it is easier to mount firmly to the engine with out too many custom brackets.
downsides? obviously a heat source and packaging is a concern and it does limit the size of the charge cooler.
Oh, and cost obviously

yep like anything in life there are pros and cons to everything. but i dont think mapping/calibration is an issue for jhm.

I'm sure the standard manifold can flow a lot of air but it's just adding to the distance the compressed air has to travel (with the inverted U shaped trumpets). Is it worth changing? For stage 1 probably not give the cost per bang.

i can only say what jhm have told me, they dont see any real downside to keeping the oem manifold only positives. they will use the oem manifold for stage 1,2 and 3.

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Where is the charge cooler going to go? it's the biggest problem with the rs4 in that it's all a bit "tight" under bonnet

[sar]

Where is the charge cooler going to go? it's the biggest problem with the rs4 in that it's all a bit "tight" under bonnet

Ads here is a pic of the jhm intercooler set up on the s4, although things might have changed slightly for the rs4 I expect them to be similar.

[adsgreen]

Its well hidden
Is it the metal lines going to the throttle body area?

Yeah I would expect the high pressure fuel pumps on the FSI to crowd that area.

[stu]

Here's what I think is a standard B7 S4 engine bay for comparison - it hasn't got the welded box on the left. That's all I can see different.

[adsgreen]

Ah yes - good spot.
So also quite a way from the cylinders.

[stu]

...and what's that weird thing where the battery should be in the JHM pic?