High Compression SC motor on E85
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Joined: Sep 2004
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From: Stockton, CA
E85 really is a totally different animal than "normal" gas....mostly since its nearly impossible to "knock" E85....so the boost and timing go WAY up and the HP follows with it....
However.....since this seems to be a 2nd level project....I gotta ask WHY.....my 2nd question...what transmission are you putting behind this 26+ PSI E85 boosted project? I ask since NO 5 speed will hold it for very long.....with 5L, 32V with better cams and 26+ psi you are talking SERIOUS HP...like a 5 speed will last minutes power level.... which begs the ???
WHY, what is your end game....do you want to throw down a monster (record) 928 dyno pull...... Do you want to do Mojave Mile? Do you want to do ORR? I won't even ask about track or road course stuff since that is far too much power.... This type of HP on the street is totally silly....
However.....since this seems to be a 2nd level project....I gotta ask WHY.....my 2nd question...what transmission are you putting behind this 26+ PSI E85 boosted project? I ask since NO 5 speed will hold it for very long.....with 5L, 32V with better cams and 26+ psi you are talking SERIOUS HP...like a 5 speed will last minutes power level.... which begs the ???
WHY, what is your end game....do you want to throw down a monster (record) 928 dyno pull...... Do you want to do Mojave Mile? Do you want to do ORR? I won't even ask about track or road course stuff since that is far too much power.... This type of HP on the street is totally silly....
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From: Las Vegas
For some ****s and giggles, I am going to put together an engine with high compression and then boost the hell out of it. This is just a motor of extra parts I have (except for the heads - they are new rebuilt)
So it will be an S3 bottom end, all stock except for some changes to the oil pan distance as well as the piston rings (standardized 951 rings)
The heads will be S4 (3R I think we call them here - from an 89).
So this should net a relatively high (but not for modern standards) CR of 12:1 or so. But I will be boosting it with a Novi 2000 as high as I can go.
The key will be three things, and I think with these three things it will run great and not blow anything up except for everyone's mind:
1) Aggressive cams - reducing the dynamic compression ratio
2) Adaptronic ECU and minute control over timing on each cylinder and injection into each cylinder
3) E85. (high octane, superior charge cooling, different burn and flame front characteristics)
One of my questions is this:
I don't actually think the S3 pistons need to be notched. I think that with the valve timing sorted, the piston never gets near the valves unless something is broken. Any comments on this?
This will be assembled quick and dirty (well, not dirty but surgically clean, but you know what I mean) and the only big hurdle at this point, well, two, are:
1) S4 intake with side plates welded to something so I can do a front mount throttle body
2) The ECU loom (which I am working on)
So it will be an S3 bottom end, all stock except for some changes to the oil pan distance as well as the piston rings (standardized 951 rings)
The heads will be S4 (3R I think we call them here - from an 89).
So this should net a relatively high (but not for modern standards) CR of 12:1 or so. But I will be boosting it with a Novi 2000 as high as I can go.
The key will be three things, and I think with these three things it will run great and not blow anything up except for everyone's mind:
1) Aggressive cams - reducing the dynamic compression ratio
2) Adaptronic ECU and minute control over timing on each cylinder and injection into each cylinder
3) E85. (high octane, superior charge cooling, different burn and flame front characteristics)
One of my questions is this:
I don't actually think the S3 pistons need to be notched. I think that with the valve timing sorted, the piston never gets near the valves unless something is broken. Any comments on this?
This will be assembled quick and dirty (well, not dirty but surgically clean, but you know what I mean) and the only big hurdle at this point, well, two, are:
1) S4 intake with side plates welded to something so I can do a front mount throttle body
2) The ECU loom (which I am working on)
Thread Starter
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Joined: Dec 2001
Posts: 25,186
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I have had two cars that I ran ethanol in for a total of 30,000 miles. I learned a lot with them. Those were stock engines and the second was with porkens chips with 36lb injectors.
It really is a great fuel for many reasons.
It really is a great fuel for many reasons.
Thread Starter
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Also I had a thread called SAR "some assembly required" and the second car was a beast on e85 with porkens chips.
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It is different. It's knock limit is something that not many people have found. Since its okay to blow up perfectly good engines now per Tuomo, I'll be testing the limits just like our strangely named rennlist turbo hero. Lol
As to usage - I have wanted to do something similar for a long time. I will take it to places like willow springs and maybe Las Vegas. It has a rebuilt 5spd in it with pieces from Mike Simard for the clutch.
I break automatics, not five speeds. It's my thing. With traction control connected to fueling and retard I know for a fact you can make gears last. I'll not be racing professionally and i don't know anyone who has broken a 5spd just going to DE's and street driving, do you?
But first I mist figure out these valve pockets!
As to usage - I have wanted to do something similar for a long time. I will take it to places like willow springs and maybe Las Vegas. It has a rebuilt 5spd in it with pieces from Mike Simard for the clutch.
I break automatics, not five speeds. It's my thing. With traction control connected to fueling and retard I know for a fact you can make gears last. I'll not be racing professionally and i don't know anyone who has broken a 5spd just going to DE's and street driving, do you?
But first I mist figure out these valve pockets!
E85 really is a totally different animal than "normal" gas....mostly since its nearly impossible to "knock" E85....so the boost and timing go WAY up and the HP follows with it....
However.....since this seems to be a 2nd level project....I gotta ask WHY.....my 2nd question...what transmission are you putting behind this 26+ PSI E85 boosted project? I ask since NO 5 speed will hold it for very long.....with 5L, 32V with better cams and 26+ psi you are talking SERIOUS HP...like a 5 speed will last minutes power level.... which begs the ???
WHY, what is your end game....do you want to throw down a monster (record) 928 dyno pull...... Do you want to do Mojave Mile? Do you want to do ORR? I won't even ask about track or road course stuff since that is far too much power.... This type of HP on the street is totally silly....
However.....since this seems to be a 2nd level project....I gotta ask WHY.....my 2nd question...what transmission are you putting behind this 26+ PSI E85 boosted project? I ask since NO 5 speed will hold it for very long.....with 5L, 32V with better cams and 26+ psi you are talking SERIOUS HP...like a 5 speed will last minutes power level.... which begs the ???
WHY, what is your end game....do you want to throw down a monster (record) 928 dyno pull...... Do you want to do Mojave Mile? Do you want to do ORR? I won't even ask about track or road course stuff since that is far too much power.... This type of HP on the street is totally silly....
Thread Starter
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Here is the SAR car thread: https://rennlist.com/forums/928-foru...te-3-27-a.html
It has some other info in it about a stumble, but some of its about ethanol.
https://rennlist.com/forums/928-foru...te-3-27-a.html
Thread Starter
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Race Director
Joined: Sep 2004
Posts: 16,271
Likes: 82
From: Stockton, CA
It is different. It's knock limit is something that not many people have found. Since its okay to blow up perfectly good engines now per Tuomo, I'll be testing the limits just like our strangely named rennlist turbo hero. Lol
As to usage - I have wanted to do something similar for a long time. I will take it to places like willow springs and maybe Las Vegas. It has a rebuilt 5spd in it with pieces from Mike Simard for the clutch.
I break automatics, not five speeds. It's my thing. With traction control connected to fueling and retard I know for a fact you can make gears last. I'll not be racing professionally and i don't know anyone who has broken a 5spd just going to DE's and street driving, do you?
But first I mist figure out these valve pockets!
As to usage - I have wanted to do something similar for a long time. I will take it to places like willow springs and maybe Las Vegas. It has a rebuilt 5spd in it with pieces from Mike Simard for the clutch.
I break automatics, not five speeds. It's my thing. With traction control connected to fueling and retard I know for a fact you can make gears last. I'll not be racing professionally and i don't know anyone who has broken a 5spd just going to DE's and street driving, do you?
But first I mist figure out these valve pockets!
You say you break automatics.....I gotta think they were VERY weak to begin with...since a properly running unit will hold more torque for far longer than the 5 speed.....
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Three Wheelin'
Joined: Aug 2006
Posts: 1,765
Likes: 3
From: Atlanta
yea, it wouldn't be realsitic to think race cars on slicks that break trans' imply anything for other cars. The life they see is way beyond anything else you're going to do in a 928. Even the most vaunted trans' break in road race cars all the time.
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Hmm broken 5 speed from DE and street driving.... Honestly I don't think so...they all have been dedicated track beasts.....Louie at 600whp never broke a trans...niether did Tim Dey at over 500....
You say you break automatics.....I gotta think they were VERY weak to begin with...since a properly running unit will hold more torque for far longer than the 5 speed.....
You say you break automatics.....I gotta think they were VERY weak to begin with...since a properly running unit will hold more torque for far longer than the 5 speed.....
Thread Starter
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I have all the pieces coming together now. I have the honing/lapping tool and the felt pads and AN-30 paste, but before that what I will do is mock up the motor with the crank but just one rod and piston installed with the crappy rings (I have a few packs of the non-951 sets) and put the heads on. I'll sling the belt on and turn over the motor. If the valves hit, then I will stop and find out how much clearance I need.
I have been thinking about software, etc that would allow me to measure and run a simulation, but I could probably do the above physical test in one day if given uninterrupted time.
I have also sourced some GT pistons, so if this becomes too crazy, I can just go in that direction, but I really, really want this to work.
The one thing, and I think it was mentioned above, is making sure the lifters for that cylinder are pumped up. I have the WSMs - are the measurements in that documentation of what a "pumped up" lifter measures to? I have some extras and can remove the lifters for that piston and replace them with some welded old ones or maybe buy the VW solids.
I have been thinking about software, etc that would allow me to measure and run a simulation, but I could probably do the above physical test in one day if given uninterrupted time.
I have also sourced some GT pistons, so if this becomes too crazy, I can just go in that direction, but I really, really want this to work.
The one thing, and I think it was mentioned above, is making sure the lifters for that cylinder are pumped up. I have the WSMs - are the measurements in that documentation of what a "pumped up" lifter measures to? I have some extras and can remove the lifters for that piston and replace them with some welded old ones or maybe buy the VW solids.
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You mean to say that if I install and clamp the heads down properly and rotate the engine in time with clay on the piston that it won't be accurate? Are you concerned over heat expansion? I can verify this way that there is over a mm of space and that should be enough, no?
Racer
Joined: Apr 2009
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From: The Evil Empire.
Aside from heat expansion, off the top of my head - there's also a problem with carbon buildup, and possible valve float at high rpm. Also, future variations in cam timing might add up.
I have no idea what clearance is enough, but a quick google search suggested these values:
.11 inches for intake
.13 for exhaust
Which both translate to ~3mm.
Experienced engine builders might suggest other values though, so this is just some thought material.
Last edited by 9x8; Jun 5, 2013 at 05:46 AM. Reason: added "cam timing"
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I'm not an expert on the subject, but I've also considered building a franken-motor, so I did think some about proper piston-valve clearance.
Aside from heat expansion, off the top of my head - there's also a problem with carbon buildup, and possible valve float at high rpm. Also, future variations in cam timing might also add up.
I have no idea what clearance is enough, but a quick google search suggested these values:
.11 inches for intake
.13 for exhaust
Which both translate to ~3mm.
Experienced engine builders might suggest other values though, so this is just some thought material.
Aside from heat expansion, off the top of my head - there's also a problem with carbon buildup, and possible valve float at high rpm. Also, future variations in cam timing might also add up.
I have no idea what clearance is enough, but a quick google search suggested these values:
.11 inches for intake
.13 for exhaust
Which both translate to ~3mm.
Experienced engine builders might suggest other values though, so this is just some thought material.
Wow, that seems like alot.