JHM stage 1 supercharger kit

[nij]

Subscribed too, plenty of write up and photos please.

I've emailed JHM, enquiring about their supercharger kit a couple of months ago, but no reply.

[RIV]

Do they do this kit for the b8?

[lengster1]

I've already optimised performance of mine with 460ps would I gain a further 100 or not?

[docurley]

I've already optimised performance of mine with 460ps would I gain a further 100 or not?

Figures are based on stock cars so o would say you would have to calculate out the remap for starters the exhaust and CAT's I would not know but I would say no to 100th on top of your current setup.

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Where does it fit into the intake system?

the blower feeds right into the throttle body. Feeds up from below. Stock airbox is removed, aux rad is removed.

Where other superchargers replace the intake manifold, which can be a costly piece of design and limits your supercharger size/cooling size, the JHM kit basically acts as a really effective airbox and feeds the OEM intake manifold via the throttle body. Their stage 2 setup uses a very large intercooler setup. Intake Air Temps were basically ambient and even below if you fire some ice in the A/W IC reservoir.

Ah I see. Yes I remember now you can get away with that with a centrifugal supercharger pre-throttle.

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?

[sakimano]

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.

[sakimano]

I've already optimised performance of mine with 460ps would I gain a further 100 or not?

You have to think about the volume of air being delivered to the car via the supercharger, and the volumetric efficiency of your engine.

Effectively your car needs oxygen rich air + fuel + spark to make power...and adding a supercharger with a fixed pulley size will deliver a certain amount of air but that's not going to change if you add exhaust to the mix. The supercharger is fixed at XX,XXX max RPMs and that determines the maximum amount of power it can make at that pulley size.

Assuming your exhaust system is reasonably efficient (as the stock system is), you won't likely see big variances from supercharger + stock exhaust to supercharger + piggies/Milltek or something along those lines. With that being said JHM had one customer's car on hand and tested stage 1 SC + JHM catless downpipes + stock exhaust...and then tested again by adding their catback exhaust (2.75") and there were some gains with the better exhaust. They also tested another supercharged car that had a competitor's exhaust and the JHM exhaust car did quite a bit better than the competitor. There could be other problems with that car too though, keep that in mind.

Really though the supercharger is driving the bus, so if it's moving XXX CFM of air, the car's ability to make power depends more on the efficiency of the supercharger and the intake side, and will more than likely not depend on the exhaust efficiency as much as a naturally aspirated car would. A naturally aspirated car needs effective and efficient exhaust in order to actually help draw air in to the motor on the intake side. If the exhaust is choking the system (too small, poorly designed) the naturally aspirated car has a hard time. If you make big improvements on the exhaust side when you're NA, you can see the motor's efficiency improve and we have seen RS4s pick up 50 hp this way with a tune that eliminates some of the Audi ECU restrictions.

[docurley]

I've already optimised performance of mine with 460ps would I gain a further 100 or not?

You have to think about the volume of air being delivered to the car via the supercharger, and the volumetric efficiency of your engine.

Effectively your car needs oxygen rich air + fuel + spark to make power...and adding a supercharger with a fixed pulley size will deliver a certain amount of air but that's not going to change if you add exhaust to the mix. The supercharger is fixed at XX,XXX max RPMs and that determines the maximum amount of power it can make at that pulley size.

Assuming your exhaust system is reasonably efficient (as the stock system is), you won't likely see big variances from supercharger + stock exhaust to supercharger + piggies/Milltek or something along those lines. With that being said JHM had one customer's car on hand and tested stage 1 SC + JHM catless downpipes + stock exhaust...and then tested again by adding their catback exhaust (2.75") and there were some gains with the better exhaust. They also tested another supercharged car that had a competitor's exhaust and the JHM exhaust car did quite a bit better than the competitor. There could be other problems with that car too though, keep that in mind.

Really though the supercharger is driving the bus, so if it's moving XXX CFM of air, the car's ability to make power depends more on the efficiency of the supercharger and the intake side, and will more than likely not depend on the exhaust efficiency as much as a naturally aspirated car would. A naturally aspirated car needs effective and efficient exhaust in order to actually help draw air in to the motor on the intake side. If the exhaust is choking the system (too small, poorly designed) the naturally aspirated car has a hard time. If you make big improvements on the exhaust side when you're NA, you can see the motor's efficiency improve and we have seen RS4s pick up 50 hp this way with a tune that eliminates some of the Audi ECU restrictions.

Nice info, even I understood all that.

[sakimano]

Do they do this kit for the b8?

they'll only do a kit for a car they own, so likely not (since the B8 RS4 didn't get sold in north america)

I can see an RS5 kit in the future, but not an RS4 unfortunately.

[RIV]

RIV wrote:
Do they do this kit for the b8?

they'll only do a kit for a car they own, so likely not (since the B8 RS4 didn't get sold in north america)

I can see an RS5 kit in the future, but not an RS4 unfortunately.

If they do an rs5 kit, surely that should go on the b8?

[sakimano]

RIV wrote:
Do they do this kit for the b8?

they'll only do a kit for a car they own, so likely not (since the B8 RS4 didn't get sold in north america)

I can see an RS5 kit in the future, but not an RS4 unfortunately.

If they do an rs5 kit, surely that should go on the b8?

Same engine, yes, however different front end, different physically etc. And at the end of the day, JHM's opinion is that if they don't own the car, they don't want to sell the kit for that car because they want to troubleshoot everything for a full year before they sell one to you or me.

Case in point, the 4.2 FSI S5 engine which is the lower revving variant of the 4.2 FSI B7 RS4 engine. JHM wanted to develop a kit for the S5 4.2 but refused offers from customers donating their cars. People said 'but you have an RS4...and have had one since 2010...it's the same thing almost'. No dice. JHM wanted to own their own S5 and do it that way. Since there is no chance of them owning a B8 RS4, I can't see them selling the kit to B8 Rs4 owners.

They have owned their S5 for over a year now, and have launched tune, exhaust, downpipes, rotors, clutch, flywheel, and have had their supercharger on the car for 4 months already. They're still nowhere near launching the supercharger kit for the S5 to the public though, if that gives you any idea of how they like to do their due dilligence.

[hlbeckley]

RIV wrote:
Do they do this kit for the b8?

they'll only do a kit for a car they own, so likely not (since the B8 RS4 didn't get sold in north america)

I can see an RS5 kit in the future, but not an RS4 unfortunately.

If they do an rs5 kit, surely that should go on the b8?

Think APR are developing an in mani charger for RS5, maybe that will work

[manual_daniel]

I've already optimised performance of mine with 460ps would I gain a further 100 or not?

You have to think about the volume of air being delivered to the car via the supercharger, and the volumetric efficiency of your engine.

Effectively your car needs oxygen rich air + fuel + spark to make power...and adding a supercharger with a fixed pulley size will deliver a certain amount of air but that's not going to change if you add exhaust to the mix. The supercharger is fixed at XX,XXX max RPMs and that determines the maximum amount of power it can make at that pulley size.

Assuming your exhaust system is reasonably efficient (as the stock system is), you won't likely see big variances from supercharger + stock exhaust to supercharger + piggies/Milltek or something along those lines. With that being said JHM had one customer's car on hand and tested stage 1 SC + JHM catless downpipes + stock exhaust...and then tested again by adding their catback exhaust (2.75") and there were some gains with the better exhaust. They also tested another supercharged car that had a competitor's exhaust and the JHM exhaust car did quite a bit better than the competitor. There could be other problems with that car too though, keep that in mind.

Really though the supercharger is driving the bus, so if it's moving XXX CFM of air, the car's ability to make power depends more on the efficiency of the supercharger and the intake side, and will more than likely not depend on the exhaust efficiency as much as a naturally aspirated car would. A naturally aspirated car needs effective and efficient exhaust in order to actually help draw air in to the motor on the intake side. If the exhaust is choking the system (too small, poorly designed) the naturally aspirated car has a hard time. If you make big improvements on the exhaust side when you're NA, you can see the motor's efficiency improve and we have seen RS4s pick up 50 hp this way with a tune that eliminates some of the Audi ECU restrictions.

Nice write-up and very interesting, thanks. I like this thread and the lower cost SC option. I think it has got a lot of people thinking again.

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To put exhaust tuning into context for a na car, you get more movement on the intake charge from the exhaust leaving the cylinder that you do from the piston going down.
For forced induction it's all in the intake boost so you just want the gas out as quick as effortlessly as possible so bigger is usually better

[rwilsonrs4]

Be interesting to see the results , i,m not a fan of Centrifugals , but it will look very OEM when done .
the downside is , the power increases will only be significant when your well up the RPM range, thets the way centrifugals work , The M112 Rootes on mine produces significantly more power and a LOT more torque until 5k where the TTS which overtakes the PES .the PES gives real grunt low down instantly as its a positIve displacemt pump tho its less efficient at higher RPM. The TTS kit on the car which My Kit came off when he upgraded was dyno'd on the same RR at MRC so the comparisons are very real,i have both the RR charts for the PES and the TTS so it was interesing to see the difference on the exact same car with 2 different kits on , the TTS kit is definately better put together engineering wise tho .
look forward to the findings