Just browsing through PE Japan website under the V35 Skyline turbo kit I was surprised to find their stock boost was only 0.3 kg (4.3 psi) for 350 hp (crank). They explained under testing for their TT kit in 4th gear full throttle stock conrod broke at 0.6 kg (8.5 psi) boost. I remember HKS told me when testing their supercharger the conrod broke at 380 rwhp that's why the HKS supercharger stock setting was 7 psi for ~320 rwhp. Does it mean HKS supercharger is safer than PE TT kit for stock motor or just PE is more conservative than HKS?

http://www.power-enterprise.co.jp

Allen

 

Without naming brands, I'd say that SC is def SAFER than TT, but neither are SAFE.

 

what about sc vs. single turbo?

 

comparing boost values on different types of FI is really not possible. bigger turbo's will flow more air at the same boost level than a smaller turbo.

 

They blew the conrod at .6 on 100 octane gas and only 3 degrees of timing taken out. At that point, they were approximately 450-460 rear axle PS (dynapack). Also, they were not using ANY kind of fuel management except the 3 degrees across the board timing retardation. I got this from Mr. Tominaga from one of our few discussions of the kit (he was there). So, that they blew a conrod at this power level does not surprise me.

As far as what's safer, an SC or a ST/TT system, I honestly think that with same degree of tune, neither is appreciably safer at the same power levels. An argument is often made that the turbos come on strong on the low end while superchargers come on gradually. Well, this remark needs to qualified with "for centrifugal SC only", as the roots blowers like those found on the AMG cars and on the Stillen systm, come on fast at low rpms as well, but not a single Stillen car out there has blown (that we know of). This is true, and it IS harder on the engine. But again, if the SAME amount of power was made, it would not matter, it would just require a more careful tune. It is just easier to blow a TT car in the course of tuning than it is to blow a centrifugal-type SC from what i've seen. The engine failures up to this point have been due to a rod failure, rod bolt failure (ME), bad tune (lean A/F - pre-ignition, also ME, the 2nd time). This has happened to a Vortech (more than once from what I know) as well (bad tune - lean a/f). That being said, TTs make appreciably more torque than SCs do, so as a rule they are NOT at the same power levels as TTs. For example, at 8-9 psi, a well-tuned Vortech makes between 310-340 lb/ft (peak), while greddy makes 380-410 lb/ft at 7.5 psi or so (and close to 420-450 at 9-9.2 psi). So, you need to be careful when making these comparisons. I would probably not blow my engine the second time (although I am glad I did in a way) if I had a Vortech, as my failure happened at 2600 rpm where my turbos (in the high gear that I was in) make full 8.5-10psi boost (my baseline now), while the centrifugal SC would be making 2-3 psi. This is not an ideal example, as other variables were at work, but nonetheless serves to show the boost characteristics of the two systems. Also, this is not a complete explanation either, just all i can muster at this hour and after a long day. Hope it helps

G

 

Than what kind of mods, without fully building the engine, will help strengthen it? Aftermarket Billet Rods? Different compression pistons? Because I am looking into FI, but don't have the money to go all out like gurgen did. I just wanna have the horse power the the kit offers as soon as its bolted on (like greddy at about 400hp), but safely (i know its never REALLY safe). But, do I have to go all out building engine to achieve 400-500hp range?

 

Gurgen made some very good points in his post and repeated a very common theme about bad tuning which, leads me to my point. It's not that turbos or superchargers that will blow your engine. It's bad tuning that will blow your engine. You could have the safetest supercharger system in the world but it doesn't matter one iota if the tuning is bad. With that said, no matter what system you get, the most imortant thing is getting a good tune and not to skimp on this area for budgetary reasons.

 

DK is right... tuning is the most important part... however, even if the car is really well tuned, a structural failure in the rod/rod bearing/piston may still happen. There is a lot of evidence of this, not the least of which being my own failure the first time around (where a rod bolt apparently gaveway first). Therefore, a safe FI choice for a stock engine is a very conservative one, 80-100 hp gain with a VERY good tune. So far, the only ones that qualify IMO are the stage II stillen and the HKS SC (is it made for hte G's), if you are looking for an out of the box solution. Otherwise, any of the other kits at VERY low boost settings...

 

Rods and Pistons are basically all there is to a built engine. You can't changeany one of these without pulling the motor. That's why people do both atthe same time, in addition to optional items like sleeves, studs, etc. But you definitely need to do forged rods and pistons on our cars...

 

I'm starting to order all my engine parts now after beating the hell out of my car for over 15000 miles(7lbs of boost the whole time with a bunch of n2o runs).I know it will last a lot longer,I'm just expecting the inevitable.Hopefully I can rebuild it before it blows.I'm kinda anxious to build this thing myself,maybe not to the extent that the PE king(gurgen)went but close.The build shouldnt cost me more then $5000 knowing I'll be doing most of the work(except for the head work & balancing).
People need to understand that if you go FI(whether TT or SC) you better plan on the future & what might happen.
Most importantly is to get a complete kit or you will go through trial & error 'till you find the right parts & figure how to work them.
I spent the day checking out my R4 software(piggy back) and how to program it.It is easily adjustable & very precise.I guess that is why Stillen & Vortect have both chose to use it.

 

Exactly. Going FI is not cheap and like every other mechanical object, things will eventually break. Could be a blown engine if your unlucky and could be just small things if your lucky. Basically, if your going FI be prepared and have the money just in case that rainy day does come your way. Also being educated on the subject helps a lot too. Too many kiddies these days want to slap on a turbo, go fast, and not think about what could happen.

 

[QUOTE=dklau33]
TRUE STORY! happen's all the time regardless of how much money you put in, what brand, etc, etc. s.hit will happen.

 

HKS just showed their piston, conrod, cam for our VQ35 motor in the recent Japan Auto Show. That's one more good option for people who want to build their motor.

Allen

 

Absolutely correct.........you need to know the mass air flow at the exact pressure ratio (Boost pressure) as this is what produces higher power hence higher cylinder pressures.

Peter