HSV Dyno day Oct SRR
Discussion
wormus said:
I don't understand how that can be true when it depends on so many factors: fuel, IATs, compression ratio/boost? Low boost is fine on a stock, supercharged engine and you get less heat and excellent drivability.
Great a nice question Basically most BHP theory is based on WOT operation not "throttled" engine operation. In that instance compression, boost, temperatures etc mean that spark timing must be reduced from optimal in order to avoid knock. You still get power, its just not as much as you would get if you could advance timing and not get knock.
Low boost reduces heat, lowers effective compression and allows MORE timing getting you closer to MBT.
Think of it this way, can you increase compression to infinity? Can you reduce octance to 0? Can you increase temperature to infinity?
The answer is of course no. So at what point can you change these things and still let the ECU and OEM build an engine that can achieve MBT without knock?
Well thats pretty much how the stock engine is designed. Its designed to run MBT without knock. Because thats its most efficient point.
So now you add forced induction without changing anything else. You have increased effective compression maybe 50% (more pressure in cylinder) you raise heat maybe 50*C and do you think you can run the same optimal timing as OEM? No of course not. You are now knock limited & timing must reduce to avoid knock and maintain power as best as possible.
You can add timing and gain power, but you will get knock. So you cant. So what do you do? You do what you can to keep timing high as possible to retain power. You run high octane, you run intercoolers, you drop engine temps, you run cams to reduce compression temps, you coat headers, you inject meth and nos etc. You do what you can to reduce the factors which affect your ability to run MBT.
Xpuffin said:
R8VXF said:
At what point has anyone said this is a scientific experiment? I think people are taking this far too seriously. I made this as a help for people to log their results next week at an event I probably will not even be at, so thought it might be a bit of fun to be able to let people log other results that they may have in their collection. If people do not like my methodology then feel free not to participate, but to those who have participated so far and going forwards, I would like to say thank you.
With respect, being new to this forum, you are unaware of exactly how many arguments the HSV Dyno days cause. I know, I started and hosted them untill the bickering about results got too much.And as an ex moderator dealing with the justified complaints from the perf companies was also an issue.
Is all I'm saying.
monkfish1 said:
Which is what i said. Im glad you now see the "discrepancy".
I disagree that 95 octane fuel would give this result, though if it was exceptionally poor i guess its possible. But unlikely. I have done one or two FI engines in my time on which to base my advice.............
Ok, I guess thats what the logs will help with.I disagree that 95 octane fuel would give this result, though if it was exceptionally poor i guess its possible. But unlikely. I have done one or two FI engines in my time on which to base my advice.............
For the benefit of all, knock retard is not related to the actual timing that needs to be pulled to avoid knock. But related to the amplitude of the recorded knock. It ramps out over time.
Id be looking to see if there was sustained knock, or just a one off and at what area in the spark table. Sustained knock is clearly more serious. A one off less so. But -9* knock retard isnt out of the ordinary. OEM tunes Ive seen -7. In fact the guy (Bart) who blew his engine up with LPG (related or otherwise) was pulling 12 degree's on petrol! and knocking like buggery. Cue Tuner B apparently. Difference is that FI runs way less timing than NA under load so -9 is a much larger % and has a larger effect.
Mind you add in IAT adjustment for heat and unknown fuel and Id be tempted to do lots of logging. I only found out I had knock at 7000rpm at TR. Never went there since or before, so had no idea. Might just be a bad set of conditions. Occam's Razor suggests starting there to me. Also of course no point logging until its running the right fuel as the baseline is screwed.
Wyld Stallyn said:
So given that I already got a CAI, Cam, lifters, headers etc and I got 'Many' FWHPs
What's the best bang for buck Power Up mod I could do next..? *
Ported LS3 heads, stroker kit, bigger cam, 3" cat-back..... What's the best bang for buck Power Up mod I could do next..? *
- Budgetary Limitations Prohibit the Use of Forced Induction
Would probably cost the same as going FI
jonnM said:
Wyld Stallyn said:
So given that I already got a CAI, Cam, lifters, headers etc and I got 'Many' FWHPs
What's the best bang for buck Power Up mod I could do next..? *
Ported LS3 heads, stroker kit, bigger cam, 3" cat-back..... What's the best bang for buck Power Up mod I could do next..? *
- Budgetary Limitations Prohibit the Use of Forced Induction
Would probably cost the same as going FI
every DD ends like this usually 10 pages up to the event, then a page on results, then 800 arguing about the results
remember that year the rollers were running really low figures (consistent across all the cars) people went mental instead of focussing on the comparable performance compared to the previous run!
remember that year the rollers were running really low figures (consistent across all the cars) people went mental instead of focussing on the comparable performance compared to the previous run!
Wyld Stallyn said:
jonnM said:
Wyld Stallyn said:
So given that I already got a CAI, Cam, lifters, headers etc and I got 'Many' FWHPs
What's the best bang for buck Power Up mod I could do next..? *
Ported LS3 heads, stroker kit, bigger cam, 3" cat-back..... What's the best bang for buck Power Up mod I could do next..? *
- Budgetary Limitations Prohibit the Use of Forced Induction
Would probably cost the same as going FI
stigmundfreud said:
every DD ends like this usually 10 pages up to the event, then a page on results, then 800 arguing about the results
remember that year the rollers were running really low figures (consistent across all the cars) people went mental instead of focussing on the comparable performance compared to the previous run!
remember that year the rollers were running really low figures (consistent across all the cars) people went mental instead of focussing on the comparable performance compared to the previous run!
Wyld Stallyn said:
jonnM said:
Are you still running the standard LS2 inlet manifold?
Guilty if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
Wyld Stallyn said:
So given that I already got a CAI, Cam, lifters, headers etc and I got 'Many' FWHPs
What's the best bang for buck Power Up mod I could do next..? *
NOS will give you the biggest bang for your buck. Not sure it's the best, but could be worth considering. What's the best bang for buck Power Up mod I could do next..? *
- Budgetary Limitations Prohibit the Use of Forced Induction
stigmundfreud said:
buy your next mod because it makes you feel good not because of what power increase you will get as you are now into diminishing returns. Your car over stock will feel massively different, if you did heads and intake it wont feel that much different
if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
Good Point Stiggy if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
My Next Mod will be Underseal (Peace of Mind = Feel Good?)
I well understand the Laws of diminishing returns
Just curious about what could give a little more power..?
stigmundfreud said:
buy your next mod because it makes you feel good not because of what power increase you will get as you are now into diminishing returns. Your car over stock will feel massively different, if you did heads and intake it wont feel that much different
if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
agree on returns if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
stigmundfreud said:
buy your next mod because it makes you feel good not because of what power increase you will get as you are now into diminishing returns. Your car over stock will feel massively different, if you did heads and intake it wont feel that much different
if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
Good point stig. If you are still on the stock diff, that where id go next rather than power.if you are on standard gearing you should do the diff, it will give you the best seat of the pants other than going FI but we don't wanna go there!
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