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  #11  
Old 01-01-2007, 02:40 PM
RICE RACING RICE RACING is offline
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Quote:
Originally Posted by JohnA
Quote:
Originally Posted by RICE RACING
We dynoed a Toyota supra with auto gearbox and it made following

470rwkw on 11.0:1 AFR 12 deg timing 34psi boost
470rwkw on 12.5:1 AFR 12 deg timing 34psi boost
471rwkw on 12.5:1 AFR 18 deg timing 34psi boost

We have dynoed FSAE engines and made no difference in power or torque from 10.8:1 AFR to 13.9:1 and all ratios between....
My auto supra registered 5-7% more power just by trimming off fuel from the stock 10.5-11:1 up to 12.5:1
That was at holding 18psi on stock turbos.
the above was with racing modified hi output 500r autronic CDI box (it will fire anything) running elf racing fuel. autronic ECU set to throttle map mode so simple AFR program change (input new target AFR line) = instant perfect tune in that load site. it made little difference in that application........ though turbo was maxed out and cant count for other variables that may have influenced that particular result
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  #12  
Old 01-01-2007, 08:32 PM
nothere nothere is offline
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help me out, I would have though the low afr (11.)would have meant you needed more timing to compensate for the slower burn. Was timing automatically adjusted to make max power during each run?

470rwkw on 11.0:1 AFR 12 deg timing 34psi boost
470rwkw on 12.5:1 AFR 12 deg timing 34psi boost
471rwkw on 12.5:1 AFR 18 deg timing 34psi boost
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  #13  
Old 01-01-2007, 09:02 PM
JohnA JohnA is offline
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What slower burn?
I very much doubt that the speed of burn is slower at 12:1 compared to 10:1

The fastest burn speed for gasoline tends to be around 12.5:1 (all else factors being equal)
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  #14  
Old 02-01-2007, 12:22 AM
RICE RACING RICE RACING is offline
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Quote:
Originally Posted by nothere
help me out, I would have though the low afr (11.)would have meant you needed more timing to compensate for the slower burn. Was timing automatically adjusted to make max power during each run?

470rwkw on 11.0:1 AFR 12 deg timing 34psi boost
470rwkw on 12.5:1 AFR 12 deg timing 34psi boost
471rwkw on 12.5:1 AFR 18 deg timing 34psi boost
maxtiming at full power as listed on tests.

another example of timing was from a friend of mine in norway (frode) not sure if he posts here or not? but i gave him some proven parameters for setting up his WI and on pump gas.

he has a max spark lead of 13deg @ 580bhp level as recorded on engine dyno, advancing spark another 2 degree's only net'd 4bhp increase in power, afr from memory was 11.0:1 region??? from my years of experience and track data i know rotaries dont pick up any noticable gains with greatly increased spark lead (again application specific) but they do have a great tendency to deposit apex seals in the turbine housing if you go for what should work out of a text book his EGT was 840 to 850deg c pre turbine too.

we have other cars here that dont run WI at all (i want them too!) and on C16 race fuel need to run 10.5:1 AFR to live @ 36psi and only use 10 to 12 deg of advance, cars hold records in their class and infact beat others with much larger engines (12a v's 13b & 20b !) run 160mph in 0-400m test.
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  #15  
Old 02-01-2007, 02:03 AM
nothere nothere is offline
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RR, oh, those results I quoted from your post were with water injection? I missed that. Were they with great quantities of water?


John, I don't always speak very clearly, chalk it up to a liberal arts education, I was trying to suggest that an afr of 11 should burn slower than 12.5. So I think we are in agreement.
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  #16  
Old 02-01-2007, 07:30 AM
RICE RACING RICE RACING is offline
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the supra ones are on stright racing fuel (no WI)

frode's are with wi

I will have my new project ready in a few weeks and hope to add some more info
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  #17  
Old 13-09-2007, 02:44 AM
RICE RACING RICE RACING is offline
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Quote:
Originally Posted by nothere
RR, oh, those results I quoted from your post were with water injection? I missed that. Were they with great quantities of water?


John, I don't always speak very clearly, chalk it up to a liberal arts education, I was trying to suggest that an afr of 11 should burn slower than 12.5. So I think we are in agreement.
Had some other example which I forgot to post up

RX2 making 578rwhp@21psi~18psi 13B running probably WtoF ratio (cant disclose exact amounts but its *high*) depending on zone in map, AF 9.8:1 to 10.1:1 Excellent power on this richer setting and not much diff to running less rich (11.2:1 or 11.5:1).

When you run leaner even with WI ratios of a higher amount you will not be able to run as much manifold pressure on normal 98 oct pump fuel (which we only use, no dyno race fuel queens alowed) which wont give you as much power either obviously.

I always run towards richer ends pretty rare to ever use some figures stated by others unless its on a car not making much power and there is more than enough cooling capacity and fuel quality to allow such things.
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  #18  
Old 13-09-2007, 09:12 AM
JohnA JohnA is offline
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Could it be that fuel atomisation is degraded at high boost levels, so running richer mask this up?
I'm just speculating here (wildly!), but if boost pressure were very high, maybe some of the air would be moving too fast for the fuel to spread so we end up with rich layers and pure air layers.

Running richer might help shift this imbalance perhaps.

...or are the rotary inlet ports totally different?
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  #19  
Old 13-09-2007, 03:59 PM
RICE RACING RICE RACING is offline
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Quote:
Originally Posted by JohnA
Could it be that fuel atomisation is degraded at high boost levels, so running richer mask this up?
I'm just speculating here (wildly!), but if boost pressure were very high, maybe some of the air would be moving too fast for the fuel to spread so we end up with rich layers and pure air layers.

Running richer might help shift this imbalance perhaps.

...or are the rotary inlet ports totally different?
when I was doing thermodynamics my teacher did say to be that the rotary engine does have a higher index in the area of the curve in the PV diagram prior to igniton which gives higher values in those calcualted conditons during compression phase need to look through my old lecture notes but a vlaue of 1.4 v's 1.3 comes to mind (13 years ago now lol) ....... practical impact I dont know can only theroize.

The decent lab tests i have seen on either reciprocating or rotary engines boosted all do not show massive drops in IMEP as those would have you believe on the plethora of inernet tuning expert sites nowadays (even when tested down to 8.5:1 AFR's) so go figure??? I know from some decent references i have (re racecarengineer) of turbo cars, lots of those in pre fuel rationing ranup to 60% excess fuel ratios ! so another validation of the rich mindset and a necessary one to make engines live and make *maximum?* power......... if not efficeint in fuel usage terms

I think the thing with water as shown in lots of older tests is that it is so good (so long as used in sufficient qty), in my tests thus far anything under 20% water to fuel ratio still benifits in very rich AFR's without the biglosses in power asuming you have a decent igniton system to do the job at hand, and sadly most do not have anything of the sort & probably is the single biggest reason for the abnormal losses of power at these rich settings? thoughts????
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  #20  
Old 14-09-2007, 02:37 AM
RICE RACING RICE RACING is offline
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What I meant to say to clarify the above is that rich *insert figures* gives maybe 5% drop in power BUT allows 10% increase in IMEP (through extra boost ability, while things staying under less thermal stress despite extra power) so you end up with a net gain of 5% more power...... but I'm sure you kinda got what I was on about, just for the benifit of others

and the richness factor is still very important when dealing with relativley small qty's of water to the fuel volume......... hence why I still run the way I do, given the fuel being the biggest *handicap* in the system (next to me the driver/tuner lol :lol: )
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