Long time reader, first time poster...

I'm prepping my DE (03) for a HKS supercharger kit with a final HP target of ~550HP crank. I reached out to JWT who recommended a C2 intake/C8 exhaust camshaft setup which I've just received and about to install.

It only just occurred to me that the C8s are more aggressive in duration and lift, meaning the exhaust is 'wilder' than the intake. This seems pretty unusual to me considering intake and exhaust are typically matched in a set OR the intake is wilder than the exhaust.

I've since reached out to JWT for clarification but was interested to see if the community has any experience with this kind of setup?

Thanks

 

Air is being forced in through the intake and needs to escape as efficiently as possible?

 

I wouldn't run those aggressive cams with that supercharger but it's up to you, those are going to like to rev and you risk overturning the supercharger. That supercharger with the max boost pulley is going to need to stay within factory rev limits. I'm doing the same kit eventually, I'm going with HKS cams, they are mild but will still make max power at 6800 RPM.

 

Thanks guys. Yeah, I was initially going to go with a set of S1s, but I figured JWT knew what they were talking about. At this stage it's well and truly too late, so I'll live with the result (how bad can it be?). I'll be running NA for a few months until I get my hands on the SC, so it'll be interesting to see how they behave in the meantime.

I mean, I'll keep the factory rev limit but perhaps to your point I'm missing out on a little extra top end by not pushing it further.

I'll update when I hear back from JWT again.

 

The thing with HKS supercharger is not a lot of people run it so info isn't as common place, if you don't have the supercharger yet you can always go with a Vortech.
Read the threads here about the HKS unit and you'll get a better idea about the unit over spinning it so my knowledge will severely impact it's life.

 

Totally, I've been trying to research the HKS for 6 months. I don't have a great objective reason for wanting the HKS over the Vortech, but that's the way I'm going. (Because HKS?) Still happy to be a guinea pig for the community though.

Re over-spinning, my understanding is the only way you can do that is by using too small a pulley. The supercharger turbine is driven by the crank (via reduction pulleys), therefore in a linear relationship with RPM. Unlike a turbo, which is driven by air-flow, and absolutely impacted by cam profiles- hence the need for waste gates to control boost.

Happy to be corrected on that on though.

 

Yes, it is driven by the engine but not 1:1. If you read over that thread you'll see they had issues, the highest boost pulley is the smallest and will be the one you need for your power goal.

 

To elaborate that supercharger will never run at 650 rpm, or 7000 rpm for that matter, it's much higher. The limit on that unit is 100,000 rpm, that should give you an idea.

 

Yep, I know all that, but your original reply was suggesting the larger cams were somehow going to affect the supercharger RPM, which they won't. Only the pulleys will make that difference.

I don't plan on going any smaller than the 100mm pulley so I may have to settle for a touch less power, but HKS is claiming over 500 crank HP.

I'm really just trying to understand the JWT's thinking in the larger exhaust cam. Appreciate the help all the same.

 

I was more referring to sending the powerband too high for it to work out in your favor if that makes sense?
You would have a rough idle and low RPM response when it is totally unnecessary. As for the higher exhaust I'd agree with the previous comment, there is no variable timing on exhaust so it's probably to allow for extra flow.
HKS is vague with that statement, I want 500 whp from the kit so maybe a bit too ambitious but I'll cross that bridge when I get there.

 

This is what I made my "build list" around, I'll probably be running 11:1 pistons tho.

 

Nice. I've been wondering how far we can push the CR, assuming the boost won't exceed output from the 100mm pulley. When are you expecting to have the build complete?

Like a few others here, I don't want to deal with the complications of a TT setup, so I'm keen to see some optimal builds around the HKS kit.

 

Right now it's going to be a bit, wanted to get it done within the next 2 years, but someone decided to smash my DD launching me into a ditch. Now I have a car payment again because I decided I wanted a nicer DD lol.
Hopefully within the next 3-4 years. I want a built long block which isn't the most economical thing. Might have to explore other options.

 

Update from JWT: Our cam engineer says that with forced induction, normally these push larger volumes of air into the cylinder and then have a higher pressure of exhaust to expel so boosted and N2O vehicles respond well with cams set up this way.

They'd also clarified using S1/S2: The JWT S1/S2 cams are too small for your modifications. Those are only for a mostly OEM stock engine with a few bolt-ons.

 

cant wait to hear it

 

It's up to you, I know that if I want to keep a 7k redline and S1 cams put the peak power at 6800, a bigger cam isn't going to help a whole lot. It will have way more compromises with them as well. Turbo and NA they are 100% right tho.

 

For sure, not trying to prove you wrong or anything. Thought the community would appreciate JWT's $0.02 as well.

@2004Black350z I'm looking forward to it myself. I'm most interested in how it behaves NA in the meantime (before I add the HKS). I'm also installing a G4+ Xtreme, dual WBs and an IAT in the next month to get it setup and familiarise myself with the software.

 

The info is appreciated. I was going to chime in with the ol' "Well, it's blown, therefore, intake charge/velocity/volume is sufficiently high already but the exhaust needs help." I ran a 3.0L with BAE turbo (built on 2.8 L28E block) back in the early-mid '80s, used a Racer Brown cam that was relatively mild/stock on the intake side but added overlap, valve lift and duration on the exhaust side. Wasn't sure if that applied here but don't see why not since physics haven't changed. Ha! But yes, good info.

 

Didn't take it that way, I'm interested in seeing the results for sure and was just adding my feedback from what I've heard over multiple years of researching this kit (which isn't common to begin with)
I'd contact HKS or a company that has actual experience with this kit with the max boost pulley to see what the max RPMs would be for the engine. Either way I'm keeping my redline at 7k and shooting for a near redline power peak. Keep us updated!
Also does the G4 have a built in MAP? Otherwise I'd recommend getting one to read boost.

 

What you're saying makes sense; the larger cams have the potential to move the power curve beyond a reasonable redline for the HKS. Not only that, moving the curve further up the range takes away some low-end power. I'm not keen to go any higher than 7k so definitely a consideration.

I haven't seen it anywhere, but I'd love to know the internal gear size of the blower to calculate the theoretical rpm of the inducer against crank rpm. I might try my luck directly with HKS.

And yep, internal MAP on the G4. It's a pretty trick unit with a tonne of functionality that will probably go unused. Overkill while I'm NA, but it'll be fun to tinker with.