sentry65

iTrader: (11)

haven't tracked the car yet because it has never been safe to beat on it with how low the fuel pressure would get. Running a booster pump was just a temp fix and is having issues with my pump now that my boost isn't slipping at 10 psi and I can reach 12 psi

Now I can't safely even go above 5500 rpms until I solve the fuel pressure issue on my car. It was only hitting 25psi of fuel pressure at redline so you have an idea of how dangerous that is for then engine when it should be more like 60psi. Before with the booster pump and 10 psi, we were able to get fuel pressure to stablize at around 40 psi at redline which was somewhat acceptable pressure

I'm stubborn though and don't want to just replace my pump assembly with an OEM one which might not even work. I'd rather get the CJM one which would eliminate any possibility of the fuel pump or pump assembly being the issue

...so let's say it's been frusturating. I bought a new helmet so I'm ready to go as soon as the car is ready.

robbycolli

iTrader: (8)

10 lb pulley. max boost was 9.7 while tuning.

robbycolli

iTrader: (8)

Sentry or others... ever had issues bending spark plugs? I have bent one on each side of the engine in three weeks.

BriGuyMax

iTrader: (4)

That's called detonation...I would get your car re-tuned ASAP...and don't go full throttle until you do unless you want to buy a new motor.

robbycolli

iTrader: (8)

thanks BriGuyMax... my engine guy says it's the piston coming up and tapping the gap shut. is this true?

detonation sounds as if the engine is not firing correctly. what does detonation mean and does it sound like this is happening to my engine?

booger

iTrader: (6)

You shouldnt boost that motor till you get it tuned . Pistons dont hit spark plugs and close the gap . But detonation will close the gap , and break off chunks of your piston ringlands . You will be rebuilding if that happens .


The 448whp and 360trq are great numbers . ANd the trq. is right on par with a SC . Vortechs always seems to be 80 to 90 trq. less than the whp numbers at that powewr level and I wonder about numbers I see that show higher trq. than normal . Im surprised you are able to make 448wp with 440 injectors . But I guess the FMU is raising the fuel preasure enough to make up for it . Are you still using the 6 to 1 or 8 to 1 washer in the FMU ?
The parasitic loss from SC is far greater than people think it is . ANd when your reaching close to 500whp , the loss is getting close to 100whp . I would like to see the dyno with the boost graph on it . I like to see if your belt is slipping and when it starts to slip . You guys that run the 2.87 pulley should be making around 12psi .

sentry65

iTrader: (11)

I'm pretty sure I asked you this before, but what is the source you got that info from?

I've done calculations from the formulas on Sport Compact Car's website as well as Corky Bell's Supercharged book (I can post what those formulas are if needed - I can also take a picture of the pages in Bell's Book) and came up with the numbers that I posted which were about 1-3 crank hp difference between the two sources...They obviously seem to conflict with your source.

If I were to guess off hand what the parasitic loss is at 500whp based on the how I've been calculating it and how it's exponentially rising, it'd be like around 50-55 crank hp lost at that power level. I could see it being 100whp of parasitic loss when you reach around 550whp or so though

booger

iTrader: (6)

You and I both know you cant pin point exact parasitic loss . But Im going by the know how of several guys that built and raced V8's and inline 6's with SCer's . And switched to turbo's with the same motors and cars . Also the artical in DSport mag that stated....for 600whp , you need to supply enough fuel for 750whp because of the parasitic loss . Ive read Corky Bells book , and I dont recall a solid formula to figure out exact or estimated loss . My memory isnt that good either though . Either way , I'll believe hands on knowledge of SCer's and parasitic loss , before I can believe estimated loss on paper .

And just to add . As the psi builds in a SC , the harder it gets to turn that blower . So parasitic loss goes up as PSI builds also.

sentry65

iTrader: (11)

I disagree to a point. I think the sequence of forumulas aren't a bunch of BS and it's interesting that top fuel dragsters actually know that the supercharger sitting on their engines take 400hp to turn the blower. You're just about always going to be estimating some portions because the elevation, intake temps, ambient temps, the difference in temps before and after the intercooler, etc etc are always going to be varrying


IMO there comes a point when working with the same displacement/power engine that a supercharger's parasitic loss is going to prevent you from making anymore real power. So I agree with you that switching to a turbo setup on the same size engine is probably a good move for making a huge amount more power.

I guess we just disagree then about at which point on a 350Z with a vortech that 100whp of parasitic loss is occuring.

That Dsport article said to figure out how much fuel you need, you take whp divided by .80 for Turbo's and N/A ....and whp divided by .70 for SCer's

actually...doesn't it seem weird that turbo and NA would be lumped together seeing that a turbo setup is going to be at the very least, slightly more parasitic than an NA setup?? weird

also if that rule is a hard constant rule for every psi setup, then a 340whp base vortech setup on a Z/G would need 485whp worth of fuel!!!! How the hell can the stock injectors even keep up with that unless you want the fuel pressure to turn the car into a really large explosive device? Obviously Dsport meant that as a rule of thumb after a considerable amount of parasitic loss has occured. I actually wonder what data Dsport had to come up with those figures.

When Dsport used a the normal 3.5 liter engine to drive a T-trim blower that's 20% larger (probably needing 20% more power to drive, not to mention is also 3% less efficient than the stock vortech blower) I'm not suprised that they ran into parasitic loss issues. If you go to a 4.24 liter engine that's 20% bigger, you add more headroom so you can be better matched with a 20% larger blower. Then the loss in efficiency with the T-trim blower can most likely be evened out with some head porting

kinda like if you took one of those top fuel blowers that need 400hp to drive and put one on a Z/G. The blower wouldn't be optimized for the engine size at all and in that case the Z engine would probably not even turn the blower enough to make positive boost



I'll find the page. It's on the right hand side about halfway through book in one of the middle chapters. I have it bookmarked. I'll post the page number etc when I get home. It factors in your engine size and compressor efficiency and CFM etc. Corky seems to oversimplfy it though compared to all the extra crap Sport Compact Car uses to calculate or estimate parasitic loss


I agree, that's why there's more parasitic loss at redline than at 4000 rpms like I was saying earlier

booger

iTrader: (6)

actually...doesn't it seem weird that turbo and NA would be lumped together seeing that a turbo setup is going to be at the very least, slightly more parasitic than an NA setup?? weird

I think you got mixed up...its N/A and SC that are figured together .


also if that rule is a hard constant rule for every psi setup, then a 340whp base vortech setup on a Z/G would need 485whp worth of fuel!!!! How the hell can the stock injectors even keep up with that unless you want the fuel pressure to turn the car into a really large explosive device?


If you're going by what I said that 600whp needs 750 whp of fuel . How do you get 340whp needs 485whp worth of fuel ?????? At 600whp you need 750 worth of fuel , thats 150whp worth of fuel over your true whp . Cut that down to 340whp and the fuel needed would be closer to 400whp . Im not doing the math. .

ANYWAY!!! .....Great numbers Bwicked....enjoy the car !
Sorry to highjack the thread !

clemlover15

iTrader: (3)

dude, thats great you must be real happy!!

sentry65

iTrader: (11)

http://g35driver.com/forums/showpost...&postcount=155

that's what you said - i dunno, I didn't read that article. I guess I caught your typo then?

that's even stranger then that a SC and NA are lumped together. So a SC is just as inefficient as NA with the same amount of parasitic loss???? ...that's even weirder



in the case of turbos - which type of turbos are we talking here? small turbos that spool up quick and make most of their power at mid rpms, or big turbos that spool up slower and make the most power at high rpms? It makes a big difference, because you will NOT be able to take a small turbo and make it perform well in the upper rpms when you add 200whp to a 230whp engine. You can add a million psi, but a small turbo will just fall on its face due to not being efficient in that rpm range when combined with a certain size engine

Also what type of supercharger is that article talking about? Roots/twin screw, centrifugal, or something like a whipple?



according to that rule (from what you posted on that link) is true, then a supercharged 340whp/.7 = 485.71whp worth of fuel needed to support itself
600whp/.8 = 750whp for turbo
600whp/.7 = 857whp for a SC


those formulas IMO are variable and only seem to apply when you've reached the "max" efficiency of what a properly sized FI kit for your engine will do. And even then what if you had a tiny turbo vs a big centrifugal SC? I understand the point they're trying to make which I think is:
If you are focusing on maximum power for a certain rpm range and are comparing two FI kits that both excell at making power in that rpm range, then the turbo requires 10% less gas because it doesn't have as much parasitic loss.

we have yet for someone to release a "large turbo" ST kit that is focused on making upper rpm power, but my guess is it would definetly make more power up high than a high boost vortech

booger

iTrader: (6)

Yes....I was wrong . The fuel requirement that the artical in DSport mag was for Turbo's and N/A.......SCer were more .

Now .... let Bwicked have his thread back

BriGuyMax

iTrader: (4)

If your "engine guy" really said and believes that then you need a new engine guy. The only way the piston is going to touch a spark plug is if the piston seperates itself from the rest of the rotating assembly has a party with your cylinder head.

Yes...detonation is the fuel/air mixture violently exploding instead of burning evenly. It ruins spark plugs and puts lots of stress on headgaskets and pistons.

Quamen

iTrader: (14)

Nice numbers bro!

I should hopefully have my Z up and running in June or July and I am going to see if there is anymore room to gain some effecincy out of the Vortech headunit by using a self contained oil system with synthetic oil. I have also been considering another option similar to the T-trim upgrade but much cheaper. It's something that I may gage interest in for those who are looking to gain some more power out of their V2's. A billet impeller replacement. There is about 10-15% more flow that could be achieved by this over the stock impeller.

SupermanZ

iTrader: (11)

Nice #s

Bwicked

iTrader: (17)

thanks guys for all the replies! I had some fun testing it out 2nite!!! lol. ran another good buddy of mine that has a Kenne bell supercharged cobra with roughly 550-565rwhp and 500-520 tq. with a out of the box tune. was closer then i thought!! only about 1 car and half loss! i was very impressed! go weight!! lol.his car runs mid 11's so were assuming on slicks with my car i should be in the high 11's. CANT WAIT!! lol.


booger as for the washer in the fmu, I have no clue, gRD did everything from the instal to the tune. so I guess they knew what had to be done right to get it to this level.