Originally posted by Vivek
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Let's talk boosted M42's
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past:
1989 325is (learner shitbox)
1986 325e (turbo dorito)
1991 318ic (5-lug ITB)
1985 323i baur
current:
1995 M3 (suspension, 17x9/255-40, borla)
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Originally posted by wazzu70 View PostWhat is your power level? I dont see any way the stock cams are your limiting factor unless you are pushing major power. Im sure the issue is elsewhere in your system.
The cams are limiting factor anywhere upwards of 300hp. You need a more agressive cam if you want to make more power.
Turbo M42 Build Thread :Here
Ig:ryno_pzk
I like the tuna here.
Originally posted by lamboButtchug. The official poster child of r3v.
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How do you figure that?
Whats your backpressure ratio? IATs? Who made your spark map?
Sorry, I dont know the details of your build off the top of my head. I would be very very surprised if your cams were actually the limiting factor. Even though I would be incredibly surprised, if you have the data to back it up I could become a believer :)
Edit: thats not to say you cannot benefit from cams, its just that cams rarely hold anyone back in FI even if its not the most efficient route.Last edited by wazzu70; 02-23-2013, 02:26 PM.-Nick
M42 on VEMS
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What do you guys know about e85? Is it as simple as a retune with twice as much boost, tons more power, and a similar strain on the motor (10psi on regular gas, 20 on e85)?The first car I ever rode in was an e30
Originally posted by Cabriolet
Wish you the best and hope you don't remember anything after 10pm.
1992 Mauritiusblau Vert
2011 Alpinweiss 335is coupe
2002 540i/6 Black/Black
2003 GSX-R 750 (RIP)
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Not quite. You need a fuel system capable of flowing considerably more than with gasoline. E85 takes a lot more volume of fuel to get a stoich burn than gasoline.
E85 has a lot of advantages though, its a much cooler burning fuel and it has a very high octane.
You just need to build your fuel system to be ethanol compatible and flow enough volume.-Nick
M42 on VEMS
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Originally posted by Vivek View PostWhat do you guys know about e85? Is it as simple as a retune with twice as much boost, tons more power, and a similar strain on the motor (10psi on regular gas, 20 on e85)?
i suggest not thinking of it as a "power adder" at all; rather, a less-detonation-prone fuel that's going to give you a little (emphasis: LITTLE) extra margin for error.past:
1989 325is (learner shitbox)
1986 325e (turbo dorito)
1991 318ic (5-lug ITB)
1985 323i baur
current:
1995 M3 (suspension, 17x9/255-40, borla)
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Originally posted by dk View Postyou are expecting WAY too much of e85.
i suggest not thinking of it as a "power adder" at all; rather, a less-detonation-prone fuel that's going to give you a little (emphasis: LITTLE) extra margin for error.The first car I ever rode in was an e30
Originally posted by Cabriolet
Wish you the best and hope you don't remember anything after 10pm.
1992 Mauritiusblau Vert
2011 Alpinweiss 335is coupe
2002 540i/6 Black/Black
2003 GSX-R 750 (RIP)
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Originally posted by Vivek View PostThat's really what I thought. I'll consider it, see if it's worth it. Put it this way, if 10psi is reliable on a stock engine running 91 octane gasoline, what boost should one be looking at to run e85 with the same reliability?
What you really need to be concerned about is toruqe on the bottom end. Just because the fuel can handle the cylinder pressure does not keep the rods inside the block :)-Nick
M42 on VEMS
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Originally posted by wazzu70 View PostHow do you figure that?
Whats your backpressure ratio? IATs? Who made your spark map?
Sorry, I dont know the details of your build off the top of my head. I would be very very surprised if your cams were actually the limiting factor. Even though I would be incredibly surprised, if you have the data to back it up I could become a believer :)
Edit: thats not to say you cannot benefit from cams, its just that cams rarely hold anyone back in FI even if its not the most efficient route.
lol okay backpressure ratio? im not sure if thats really relevant and No i dont know it. Im not a master at tuning principles and to make it clear I did not tune my own engine. IAT's are in the low to mid 80s driving. the dyno however was a different story. What does spark have to do with it? Yes its fully adjustable with Ms but the stock cams are the constant. The stock intake on an m42 is something that is limiting also. If you really want to be anal you could say that the whole m42 head is also limiting, and technically youd be right. I have this feeling that you might tell me to retard my timing for more power... or something along these lines. :tsk: :tsk: :tsk:
im still interested as to what you think is limiting me if its not the cams. As far as im concerned a 300hp m42 is not limited. This was the goal for my build.
built m42 8.5:1
ported and polished head
gt2871rs @ 19psi
1000cc injectors
Full pnp MS
255lph fuel delivery
thats pretty much all info needed for this discussion.Last edited by Dj Buttchug; 02-23-2013, 04:00 PM.
Turbo M42 Build Thread :Here
Ig:ryno_pzk
I like the tuna here.
Originally posted by lamboButtchug. The official poster child of r3v.
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Originally posted by Dj Buttchug View Postlol okay backpressure ratio? im not sure if thats really relevant and No i dont know it. Im not a master at tuning principles and to make it clear I did not tune my own engine. IAT's are in the low to mid 80s driving. the dyno however was a different story. What does spark have to do with it? Yes its fully adjustable with Ms but the stock cams are the constant. The stock intake on an m42 is something that is limiting also. If you really want to be anal you could say that the whole m42 head is also limiting, and technically youd be right. I have this feeling that you might tell me to retard my timing for more power... or something along these lines. :tsk: :tsk: :tsk:
im still interested as to what you think is limiting me if its not the cams. As far as im concerned a 300hp m42 is not limited. This was the goal for my build.
built m42 8.5:1
ported and polished head
gt2871rs @ 19psi
1000cc injectors
Full pnp MS
255lph fuel delivery
thats pretty much all info needed for this discussion.
The backpressure ratio is important to make sure your turbine is not choking out. You want to make sure the pressure in the collector is less than the pressure in the intake. If its not, then your turbine is the restriction. Since the GT28 is a smaller turbine, I figured this may be the case around that power level.
What do you mean the dyno was a different story regarding IATs?
The spark map is essential to getting decent power. Instead of telling you the spark map needs to be retarded, I was actually thinking its possibly too soft. Most people run "safe" timing maps which really aren't any safer and just leave a ton of power on the table!
When you say limited, do you mean you keep adding boost without seeing a gain? I guess we need to define what you mean by limited to get an understanding. All that stuff is a restriction at some point, but it seems pretty unreasonable to be this point.
Is the 300hp wheel or crank? Big difference, but either one is a respectable number for sure. Thats got to be a fun car!-Nick
M42 on VEMS
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Why does no one DASC the m42?I want a nice set of smoked MHW's (I know, get it line)
Free Stuff!!:http://www.r3vlimited.com/board/showthread.php?t=273454
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Originally posted by CrusherCurtis View PostWhy does no one DASC the m42?
if someone made a centrifugal for this engine, i'd be on it, but i can't use a roots.past:
1989 325is (learner shitbox)
1986 325e (turbo dorito)
1991 318ic (5-lug ITB)
1985 323i baur
current:
1995 M3 (suspension, 17x9/255-40, borla)
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Originally posted by CrusherCurtis View PostWhy does no one DASC the m42?The first car I ever rode in was an e30
Originally posted by Cabriolet
Wish you the best and hope you don't remember anything after 10pm.
1992 Mauritiusblau Vert
2011 Alpinweiss 335is coupe
2002 540i/6 Black/Black
2003 GSX-R 750 (RIP)
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