thank you very much for your answer

 

Hey Speedracer, I read your post itemizing each FI option. After reading the forum over the past couple of years, I've got to say you nailed it. Your opinion is a reflection of the opinions I've seen from owners of each option to the tee. In otherwords, great post.

Now, lets see how the HKS people post over the next year to see if this really is the best reliable daily driver option that produces decent power. Please keep us posted because this is the FI option that sounds ideal for me too.

 

GGAHAHAHAHAHA I just remembered one of the reasons I got the Stillen kit


CARB exemption!
neener

sorry, I am a bit of a treehugger

I love the stillen and can live with what it gives me

 

Yep rwhp................as I said this also depends on the performance of the exhaust system.................somewhere between 110 to 130 rwhp is real easy to achieve at low boost pressure.

Thanks

Peter

 

honestly, i don't really think it's fast compared to liek gredyy twin or vortech sc!!but overall it's a nice quality kit!!

 

i meant like greddy turbo kit.....sorry about typo

 

The only thing I don't like about the HKS S/C kit is that it uses HKS' own intake, the Super Mega Flow. The filter element used for that intake has very poor filtration:

http://www.mkiv.com/techarticles/filters_test/2/

Out of 4 intakes tested, the HKS Mega Flow is the worst, with a filtration rating of "Very Poor". I don't like this intake at all. It will allow too much dirt particles into the engine, which defeats the purpose of a filter in the first place.

Anybody know if we can fit another filter element as a replacement for the HKS element?

 

Thats a good point but perhaps its not really and issue in real life.
I am sure they thought of that when they designed their SC kit if it was as bad as that it would call into question of how reliable the kit was in the big picture. Besides there is no substitute for a clean engine bay and just regular air filter cleaning and maintenance. If you have enough to invest in FI you would probably realise an FI car in gen will require better upkeep and care.

 

Thank you.

 

You are right, a FI car will definitely require better upkeep. I guess I am just disappointed that they used an inferior filter element on an otherwise well designed kit.

 

Dracing77 - do you have AOL IM? I wanna ask you some questions about your HKS setup and your supra...I sent you a pm.

Jon
email: AGORDON3@midsouth.rr.com
aol im: danksilvia

 

Tweety-nator, warning - long post

You have raised a number of interesting points that can be confusing to some because we are dealing with many issues - at the same time - that contribute to engine performance and durability. I’m also mindful of not steering this thread off-topic so my apologies in advance.

Regardless of the form of FI, engine tuning parameters and fuel quality are of paramount importance. This can make the difference of an engine surviving at 9 psi of boost versus another identical engine failing at 6 psi.

With a turbocharger system that employs advanced boost mapping, the exact boost pressure can be programmed throughout the RPM range. This way, the boost pressure is at the optimum level at each point in the RPM range. There’s no need to forsake boost at say 3,000 rpm if the engine is capable of handling it. Naturally, it would be foolhardy to program too much boost pressure at that point. The same applies anywhere else in the RPM range.

As an aside, we can map the boost pressure vs RPM on the TT system to mimic the boost profile of a supercharger – it basically involves removing boost in the low and mid RPM range.

I’m also always mindful of comparing power figures and relating them back to engine durability. A supercharger for example that produces 320 hp requires the engine to produce some 30 to 40 additional hp because of the parasitic nature of a supercharger and the fact that the supercharger consumes that amount of power from the engine to drive it. An equivalent turbocharger system on the other hand would be producing 320 + 30 to 40 hp (because a turbo is not parasitic). So it would be remiss of me to think that the higher power figure would be less reliable because the engine is in fact under the same amount of load to produce the two different hp figures.

To put this another way, with the two vehicles producing the same hp, the turbocharged engine would be under less load than the supercharged engine because the turbo doesn’t need the engine to produce 30 – 40 hp more to achieve the same hp result.

I guess what I’m trying to say is that we’re all very mindful of engine durability. Given the correct ignition timing map, air/fuel ratio map and boost pressure map set at a reasonable 6 – 7 psi maximum – with the engine running on good quality fuel - the likelihood of engine failure is fairly small regardless of the type of FI used. It’s just that more power makes it to the wheels when it doesn’t have to drive a supercharger.

Now back to the rods. I think it's fair to say that over the years I've broken my fair share of rods in supercharged and turbocharged engines.

There are three common reasons for rod failure that I'm aware of. They are exceeding the mechanical structural properties of the rod (and in this instance you normally bend the rod, not break it)

Next is increased engine RPM. On some engines RPM increases of only 300 RPM over stock will break a rod every time. I would be very mindful of raising the RPM limit on either a supercharged or turbocharged engine at elevated power levels.

Thirdly, if the big end bearing fails (the top bearing shell can be hammered and damaged through high mechanical shock loads caused by detonation) and invariably spins - thus creating enormous thermal loads due to friction. Consequently, the rod breaks at the big end. This type of failure has nothing to do with the mechanical strength of the rod, but often the rod is blamed for being weak - which is obviously not the case in this type of failure. It all comes down to correct diagnosis.

We all know that power in the 350Z is highly addictive - no matter where in the RPM range power is produced. Let’s face it, when an enthusiast has the ability to up the boost, he generally does at some point or another. There’s an old motto that goes something like this - Crank up the boost until something breaks and then turn it back half a psi.

Happy and responsible boosting to all - it's all about the fun factor!

Peter

 

Peter,

Although I am going with a Vortech because I have decided that supercharging is the way to go for the 350z, I am a huge fan based on the press information on the soon-to-be released APS kit. APS has obviously put some serious development into this kit.

Still, when you mention the parasitic loss created by the supercharger, it's important for most readers to remember that people are dynoing at 350hp to 400hp to the wheels.....that means any parasitic loss is factored into that number....what most do then is add 10%-15% to presume the HP at the crank. That said, I still presume the APS kit would make more power than the Vortech, and have a broader power curve, most notably at lower RPMs.

The supercharger does offer some unique benefits though: Less heat, which can be a contributing factor to detonation; Additionally a few have commented that even when they increased boost, after safe tuning the HP were modest, implying that perhaps the Z responds well to a low-boost-combined-with-higher-flow solution.

Another comment I struggle with is your notion that the quality of the gas is key, not because I disagree with that statement, but because as a consumer I view such a comment by a vendor as untenable in terms of buying a reliable kit. I don't produce my own gas! I buy what I can at the pump when I'm running on empty!!! The quality of the gas is what it is!!!! I can't bring a test tube kit and run a sample everytime I gas-up. I would expect therefore that the tuning needs to account for the worst-case scenario as far as variance in fuel octane, quality, and such.

Sorry if this sounds like a knock, and by no means is this directed at APS, but I do struggle with all of the kit manufacturers and how they do stand behind, or do not stand behind their product as the case may be. I know they have to protect themselves given the installation and tuning creates such a random factor to the end result in terms of an install quality, but rather than covering their own butts at the expense of the consumer, why don't vendors offer better training and support to a registered networks of installers??? In fact i believe APS is doing this right, and I only wish the other companies would follow suit.

OK I'll get off my soap box now.....

Chris

 

Peter,

Thanks for the informative post, I learn new things everyday. You are the turbo expert, and I appreciate your response.

Just when I was sold on HKS, you go and put APS back into my head LOL

 

I agree. In my case, it's whoever has the carb # that I'll most likely go with.

 

Cool and my pleasure to input to this thread..............we all learn new things everyday.............that's the great thing about life and work experience.

I do have an awesome amount of respect for HKS though there is one aspect of the superchrager system that worries me greatly, which is the fuel system upgarde supplied in the package.

The 2 aux fuel injectors mounted pre plenum...............this in my view is a real concern as in all FI engines equal air fuel ratio/distribution to all 6 cylinders is of paramount importance..............otherwise certain cylinders may run leaner than others causing premature piston and valve damage.

It would be very interesting to install 6 air fuel probes to all 6 cylinders to see how equal the air fuel ratio is...............I suspect the mixtures wont be well balanced..............onlt time and thorough testing will tell the entire story.

Just thought I would mention this (has been on my mind for a while) as I was very surprised to see HKS utilise this fuel system approach for the additional fuel...............worth keeping an eye on into the future.

Happy boosting.

Peter

APS

 

Given that these injectors are driven by their own MAP sensor and are sized pretty decently, I am fairly sure the fuel flow would be more than adequate to each cylinder. Much easier to do this in a V engine than in an I engine

 

Great thread everyone! Nice to read a postive discussion with good information.

Jeff

 

Peter,

APS offers training and support to a "registered" network of installers? How do I go about finding a "registered" installer ? Is this true for any other FI vendors? Sorry for my ignorance but I am new to the FI game and am learning alot from you all on this thread. Thanks for all the good info.

 

Actually, you can bring a kit with you and check the specific gravity of the fuel. It isn't difficult to do, and if you are travelling outside the US it might be a good idea. But if you're buying fuel in the US, your state government does tests to enforce the octane numbers posted on the pumps. All you need do is read that number and select the proper grade.

Now Nissan tells us to use premium fuel even in the stock NA engine. While you can sometimes "get away" with using a lower grade occasionally, you will more likely get pinging, knocking, and for sure reduced performance if you do. Once you start boosting the motor even a little, 87 octane fuel is right out, 91 octane is marginal, and 93 octane works well for moderate boost levels. At high boost, race gas is the only option.

You can't realistically expect the kit makers to design their kits so they'll work on 70 octane gas left over from WWII and pumped out of a rusty 55 gallon barrel. There has to be a realistic expectation that you'll use fuel at least as good as Nissan recommends for the stock engine.