I also ask that question too. They said it's fine if you add bolt on since it changes very little regarding to fuel mixture. That came from directly from the kit designer himself.

 

I would think that the kit comes tuned safe [ rich ] like Vortech . So adding plenum and headers will help ....IMPO

 

well thats good to know. I just called a pro dealer and they said with the headers and cats It would make me run less boost but in turn the car would be making more HP so I see that is being even safer for the moter. Untill I upgrade the pullys LOL

 

A/F is basically 12 throughout the powerband

 

 

why do you say that?

 

Supercharger is belt driven. How's adding free flowing exhaust components going to lower the boost? Boost will stay constant with the extra gaining of hp due to slightly leaner fuel mixture since exhaust gas are flowing out faster.

 

It would be nice for some of you guys to run some qtr. mile times. Dynos are great but qtr. miles are where the rubber meets the road. Have all the drag strips quit for the winter? I think Mason Dixon is still running some in Nov. - near Hagerstown MD, near where some of you guys who have installed HKS in VA. And I know that if you guys got some sportin' blood in you anywhere, you're curios too.

 

there is street wars the 12th of this month

 

The world cup final is Tomorrow Sunday at Maryland international race way. Anyone going?

www.mirdrag.com - see the flyer on the home page.

Huge event, basically import vs. domestic, once a year thing.

 

My understanding is that when Turbo magazine did their dyno test and got 325.4 wheel HP on the HKS supercharger, they were running on 91 octane gas in CA. It would be interesting to see some dyno tests using the 93 or 94 (Amoco) octane gas we have here on the east coast. Might make an improvement...

My thinking is the Crawford plenum might make an improvement with the HKS supercharger. The HKS comes on real strong in the low and midrange and not quite as strong high in the rpm band just before redline. Crawford is touting a 9 hp gain with their plenum across the rpm band and a 17 to 20 hp gain high in the rpm band before redline (Sport Z magazine). Adding the Crawford plenum might help the HKS setup pull stronger at high rpms to go along with the very impressive low and mid range power and torque. It'd be nice to see some dyno runs (93 or 94 octane gas) with both modifications as well to compare with the Turbo magazine dyno run which was just the HKS supercharger on a stock 350Z. Just a thought. I like the things I'm hearing about the HKS supercharger and think a little tweeking with additional mods could result in a real strong setup over the entire rpm band with our 350Z. Who knows, the things I've mentioned and a good cat back exhaust and with high flow cats, we might get up to around 350 wheel hp power which is where I want to be with this car. And strong performance over the whole rpm band which is sweet as well.

 

I have first hand knoledge of this being the case . Yes a more free flowing exhaust will reduce boost on a SC . I had headers , test pipes [gutted RT cats ] Stillen dual cat back . At 7lb's of boost , I wonder why I couldnt make 8lb's on the Vortech . I put on Crawford cats and gained 1.5lb's of boost....but didnt gain any whp

 

is hks making the engine cover they used on their 350, or is it just a modified G cover?

 

nice kit ,good company but to much money..

 

Just keep in mind that the HKS kits design has 2 injectors in the plenum that compensates for the rearward cylinders. You might need to re-evaluate your fueling if you fit the crawford as this plenum has better distibution.

 

Agree. The design of the auxillary injector assembly tends to favor fuel flow to the rearward cylinders, taking into account the stock plenum design.

 

Good point. Thanks. Have to go to an HKS proseries dealer and get the engine managment system retuned, right. Or do you mean that I need to actually relocate the kits 2 additional injectors slightly to integrate with the Crawford plenum?

 

I was referring to the physical location of the injectors since they face and fire rearward/outward into the oncoming airstream. Relocating the injectors would be a major undertaking since the injector harness comes as one solid piece that is already fabricated to bolt into the plenum in a certain way. Forget the Crawford plenum with this set-up.

Honestly, for those who really want to play around a lot, there a plenty of other kits and options. I really think this kit is for those who don't necessarily want to play around a lot.

 

I'm sure you are right. I already had a nagging worry about exactly this issue. I just really want the Crawford plenum really bad cause it really improves the uniform distribution of air to all cylinders and for the cost, it's almost like free HP. Plus it helps engine performance most at the top of the rpm band which is just what the doctor ordered for the HKS setup on our 350Zs. And I perceived that this better equal distribution of air to all cylinders might have a general positive effect on engine reliability and longivity. But, I agree it is even more important to NOT throw off the air/fuel ratio if HKS has already built the unequal air flow of the stock plenum into its engine management equations and location of the 2 additional fuel injectors. (And I have heard before - I think you mentioned it in this thread some where - that the 2 added fuel injectors are located to compensate for the air flow in the stock plenum.) Rats. Does anyone think there is an easily effective solution to be able to use both the HKS supercharger and Crawford plenum? I think I already know you are right, but I wish there were a way...

 

Here's a good link.

http://www.chevyhiperformance.com/te...78/index1.html

Tech Articles
Busting Boost Myths



While boost seems to be the way all superchargers are rated, the key to making power is moving air. Whether a supercharger just moves air the way a Roots does or actually compresses the air the way a screw supercharger or a centrifugal does, the boost you read on the gauge is as much a function of the engine as it is the supercharger.

Let’s stuff a large-by-huge 6-71 supercharger on top of a stock 350 engine that makes a normally aspirated 300 hp. We’ll put headers and a good ignition on it, but nothing else in the way of trick engine parts. Even underdriving the supercharger (where the blower is running slower than engine speed), we could easily make 8 psi of boost. Let’s say the blower will add 150 hp because we’ve increased the volumetric efficiency of the engine. In other words, we stuffed more air into the engine.

Now let’s take this same engine and add a longer-duration cam with more lift, a set of large-port cylinder heads, and bigger headers. Now we have made it easier for the engine to move more air both in and out. Now bolt the supercharger back on with the same drive ratio as before. Now the engine makes over 600 hp, but it did so at a lower boost level. Why?

Since the engine can now ingest more air than before, and the supercharger is running at the same speed, the boost will drop because the engine is using more of the air “stacked up” inside the intake manifold. So while boost can be used as some type of reference (10 psi versus 25 psi), it’s really a very nebulous number. This is because each engine will determine the boost level it will attain based on its individual equipment. Boost is like a very inaccurate yardstick. It has some value, but it’s not as precise as you might think.