engineermike

half-n-half, I think the answer to your question is this: If you use a larger cam and lower boost to achieve the same power level, the chance of detonation is reduced. It is reduced because more compression is done by the piston (100% isentropic efficiency) versus the compressor wheel (70% isentropic efficency). The higher efficiency compression results in a lower temperature at the end of the compression stroke. Lower temperature means it's less likely to detonate.

Mike

brad8266

iTrader: (23)

yes the larger cam would allow for lower boost numbers to make a said HP number. So in that sense maybe it would reduce chances of detonation.

half-n-half

iTrader: (7)

yeah that is definitely the way i was looking at it... however... just because of lower boost numbers, is the air actually going to be any cooler? it is actually more air coming out of the turbo... ehh i guess it isnt the end of the world to know just a little theorizing.

engineermike

Go back and read the link posted earlier. The cam is fine.

engineermike

You said "making the same amount of power", which essentially means "flowing the same amount of air". So, no, there is no more air coming out of the turbo. Also, keep in mind, that heat is added when air is pressurized. If you don't pressurize it as much, then it doesn't heat up as much.

brad8266

iTrader: (23)

I read it and i tend to disagree, there is no solid proof here. Until there is I stand by saying that the torquer is not a great turbo cam.

99Z28LS1

iTrader: (4)

so duration and LSA have a lot to do with an FI application...... and the intake and exhaust lift has nothing to do with it?

i get confused when it comes to cams...... my LSA is 115 and duration is 228/228 with lift at .588 .588

engineermike

So you're saying that 645 rwhp at 6 psi boost from a turbo LSx is no solid proof that the cam will work?

I guess that's more of a rhetorical question, so there's no need to reply.

brad8266

iTrader: (23)

Yeah it works, i get that part, it still doesnt prove much. So what, i have seen a stock engine down to the exhaust manifolds make about 600Hp on like 9lbs, bone stock engine.

engineermike

I think your credibility here is now shot to hell.

brad8266

iTrader: (23)

Edit- Didnt see he had a stock block, thought it was a 402

engineermike

Keep going, this is getting good!

half-n-half

iTrader: (7)

[QUOTE=engineermike]You said "making the same amount of power", which essentially means "flowing the same amount of air". So, no, there is no more air coming out of the turbo. Also, keep in mind, that heat is added when air is pressurized. If you don't pressurize it as much, then it doesn't heat up as much.[/Q]

yeah i wasnt thinkign straight there...

brad8266

iTrader: (23)

I have no need to go on anymore, my point is proven. That GTO setup is inefficient even at 6.5 PSI.

engineermike

Okay, when YOU build a turbo combination that makes 650 rwhp at 6 psi boost, get back with us. I've built a few turbo systems and so have many others on this board. Hell, half the guys are calling BS on perdieu's numbers because they are unbelievably high. But, according to you, his numbers are dissappointing. . .

Mike

brad8266

iTrader: (23)

My bad I thought he was running a 402 CI block when I first read it, but if its the stock block then its not so bad.

But once again there is a stock Z06 here in Savannah that made 585 HP on 9psi, the car is 100% stock down to the exhaust manifolds. That is way more efficient than a head/cam turbo car making 645.

engineermike

If you do the math, the percent hp increase per psi boost is almost identical between those 2, with the "wrong"-cammed GTO having a slight advantage. The ZO6 gained 7.5%/psi, while the GTO gained 7.8%/psi.

brad8266

iTrader: (23)

I was wrong the Z06 was on 7psi stock engine. look at the powerband differences for the same PSI pretty much 6.5 PSI and 7 pSI are basically the same. Look at the HP at 3500 rpm's, the Z kills it down low and the Z keeps pulling after 5500 while the GTO falls off at 5500. The powerband of the GTO's cam is well over 6000 rpms yet it drops right off after 5500.

The Z setup is clearly a more efficient setup by far. The powerband of the GTO is horrible, doesnt pull down low and drops off way earlier then that cams powerband.

I would take the bone stock Z rear mount setup over the H/C GTO anyday.

granted the Z does have a bigger turbo.




Your buddies head/cam/turbo


The dyno differences are minimal too because I dynoed on that dyno and a dynojet and my numbers were within 2 hp.

67Firebird455

iTrader: (27)

LSA does have an effect on overlap, that's why I posted up as a higher LSA and reverse split (IE - Stealth II cam, 224/220 @ .050 on a 116?) would be more in quotes... "Efficient"... People are running decent sized NA cams and getting results just as good, so I'm not sure.

brad8266

iTrader: (23)

Where did you learn this? LSA has no affect on duration. It does have an affect on overlap.