After enjoying my JHM tune so much, I wanted to check out the other “go fast bits” they have for the 4.2L V8 on my B7 Audi S4, so I picked up a Lightweight Crank Pulley and their modified Intake Manifold. While I’m certainly not the first car with either of these parts, as they’re used & enjoyed by MANY enthusiasts in the B6/B7 S4 forums, I thought I’d give a quick review here like I do all of the other modifications to my S4. After driving around with both installed a few weeks I am a VERY happy customer, and I’ll give some notes below on each.
JHM Lightweight Crank Pulley Review
This part is very impressive, and a great “bang for the buck” mod. The JHM website downplays the impact it will have a bit, citing “This mod is not a drastic HP increase but it is a great piece of the puzzle” but I’d argue it has a much bigger impact than simply a piece of the puzzle. I found shifting to be much smoother, and the jerkiness in gears 1-2 almost completely disappeared. It’s made driving my car considerably easier to rev-match and shift smoothly, and for that alone it is well worth the $350. While JHM may be correct it doesn’t add a ton of horsepower, it does improve the drivability and “smiles per gallon” quite a bit, and is something I’d strongly recommend as one of the first mods you do. I also think it helps smooth out the hyper-responsiveness of the JHM tune in low gears, so if you have a JHM tune and this has been an issue for you, then you should make sure this is your next mod.
I debated between getting the full JHM Intake Manifold setup and just going with the spacers, but after a few emails with JHM and chatting with my local shop, I decided to go for the full setup. The JHM Intake Spacers are a great deal and help the engine with cooling, but unfortunately they can’t really be reused easily as they’re made to mate up with the OEM manifold and not the JHM modified Manifolds. While you could modify the spacers to work with the JHM Intake Manifolds, its quite a bit of work and simply better/easier to order the JHM Intake Manifold with built in/integrated spacers. Each manifold is built to order and JHM takes a stock manifold and modifies it to improve airflow and contribute more top end power. After you install yours, you ship your original manifold back to JHM so they can modify it and sell it to a future owner. Mine had about a 2 week build time, which isn’t bad all things considered. You have several options when ordering, the most important being getting the integrated spacers. I also opted for the heat shielding and ordered it in the darker grey color (my original one was light silver) to give it a slightly different but OEM look.
Driving wise, JHM reports a 16whp/22 crank hp gains with their headers installed, and about 10whp/13 crank hp with just piggie pipes. I haven’t dyno’d my car recently but I’m guessing it contributed closer to the 10whp range – it’s nothing drastic, but the car pulls really smoothly and consistently. I have no doubt it’ll help on track days and canyon runs where the engine gets especially hot, and I do feel a little more uumph in the higher range on the butt dyno.
Combined these parts work nicely with Crank Pulley helping more in lower gears and lower RPM and the Intake Manifold in higher gears and higher RPM, thus making the engine feel stronger across the entire powerband. Coupled with my vented hood, I’d venture to say my engine should remain pretty cool even after extended periods of hard driving, and as always this car puts a huge smile on my face which is always my #1 goal when it comes to modding. Thanks JHM for the great parts and supporting the platform!
PS – yes I need a new engine cover I am debating on getting carbon fiber ones or just trying to find a cheap used one. I did wipe down the engine bay prior to snapping these pics, so don’t be too hard on me!