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Old 03-29-2011, 06:22 AM   #1
phat
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Default What CR for E85 Race fuel only motor?

Hey Guys,
I'm wondering what CR i should make the engine. I'm thinking 10 to 1.
Engine will see up to 40psi of boost on E85 Race fuel.
has anyone had real world experience with high comp E85 motors?

Cheers

Ben
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Old 03-29-2011, 11:12 AM   #2
Homemade WRX
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need more details on the engine package itself. 40 psi and 10:1 on an EJ25 is going to require pulling a lot of timing than say and EJ20 or destoked/longrod set up which like higher CR and or boost/timing. Combustion chamber and piston dish are going to have some effect on your kernel and flame propogation.

This is for the World Time Attack motor, right? You guys were planning to keep it as an EJ25, right?

why isn't this in built motor? <---the section of engine 'gurus'.

I'm down for dorking it up, as always.

Last edited by Homemade WRX; 03-29-2011 at 11:17 AM.
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Old 04-04-2011, 06:14 PM   #3
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anyone?
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Old 04-05-2011, 08:30 AM   #4
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Ben,

You're asking in the wrong place and this is something that 99.99% of the population on here can't estimate or guess for you. Even then, to estimate takes a lot of computer modeling and more information on your behalf.
If you'd like to discuss it further, you can give me a call. This is something Brian Crower will shoot from the hip on. Basically you have two routes; experience or calculation.
My closest experience with this was 11.5:1 with 19 psi (race map, lower boost for 'endurance') without an intercooler, on a long rod oversquare build. EJ25, intercooled for road race use, you can expect to see guys running mid-high 20's with about 10:1 with a good quench pad.
Without really getting into details on your specific setup, I'll say an EJ25 with a good crown design and pulling timing (in trade for pre-ignition cylinder pressure) will be hard pressed to be able to hit a pressure ratio of 3.8'ish absolute on E85.

Regards,
Micah

Last edited by Homemade WRX; 04-05-2011 at 11:18 AM. Reason: oops put auto-x
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Old 04-05-2011, 11:00 AM   #5
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For what it's worth we run about 10:1 in our Element Tuning race engine for time attack. With 110 octane Sunoco we ran up to 30 psi (don't remember the power level) and with Hydramist (80 water/20 meth) we made just under 700 whp on a break in tune.

The nice thing about high compression is that it allows you to back off the ignition timing which we find leads to high loading of the piston against the cylinder wall, increasing scuffing. Also keep in mind that your static compression isn't the same as you dynamic compression and camshaft choice along with AVCS tuning effects your actual compression ratio. For instance we bumped our intake cam timing about 7.5 degrees for testing and it increased our compression testing results by about 20 psi which is about equal to what you see with a high compression piston and no advance.

From what we've tested it doesn't change your peak power as much as you think it would but for us the better throttle response, quicker acceleration climbing up to peak boost, and the fact that we could back off of ignition timing makes it all worth it.

Thanks,
Phil Grabow
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Old 04-05-2011, 11:23 AM   #6
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Phil, was that 30psi/700whp for track duty (safety for heatsoak) or for hotlapping?
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Old 04-05-2011, 03:51 PM   #7
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Quote:
Originally Posted by Homemade WRX View Post
Phil, was that 30psi/700whp for track duty (safety for heatsoak) or for hotlapping?
I don't know I've never raced it at that power level yet (with the new car) . Now when I tuned it that was a very conservative tune at 700 whp but as you mentioned coolant temp could be an issue for more than one lap.

We are at a grip level now where we can't keep oil around the pickup even with 5 quarts in the sump. So at this point I would say there is zero chance it would make it more than a couple laps at that power level. We are putting together a dry sump for this weekends race but I only run 500 hp for NASA.
I will be upping to 700 whp this summer for a couple of events and thank God I will be on a dry sump.
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Old 04-05-2011, 03:57 PM   #8
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Yeah for a serious track subie, a dry sump is pretty much mandated to keep the engine alive.

Who's pump are you guys running? Just running a two stage to scavage from the pan or are you going to pull from the heads too?
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Old 04-05-2011, 04:24 PM   #9
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Quote:
Originally Posted by Homemade WRX View Post
Yeah for a serious track subie, a dry sump is pretty much mandated to keep the engine alive.

Who's pump are you guys running? Just running a two stage to scavage from the pan or are you going to pull from the heads too?
Because we had less than a week to put this together we are going with a Aviaid scavenge 2 stage pump only. I'm hoping, hoping, hoping, the OEM 11mm pump will be able to pull enough oil from the 2 gallon reservoir. After this race I'm going to want to move forward on finishing up the kit and having the correct pulley machined so we can run the 3 stage pump.

We are going to scavenge from the oil pan only for now and we'll hopefully puke the oil from the heads into the reservoir on blow by alone.
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Old 04-05-2011, 05:19 PM   #10
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We're pretty happy with our powerband. The last motor was 9.2:1 and this one is 8.5 because we had to put it together in a rush and it was what we could get. Peak power and spool didn't really change between the two. I think with high compression we did 689@32psi and then with 8.5 we made 675@30. This was with e85 on a 35R.


Our oiling system has held up great with just a big Moroso pan, accumulator, and Cosworth 12mm pump. At cal speedway last year we were revving to 8500 and doing like 2g on the bank. Then when the last motor came apart the bearings all looked great. The cosworth motor we used to have would rev even higher and also had no issues using their pump and pan so I'm just not convinced the cost and complexity of a dry sump is completely worth it.

Too bad we're on opposite sides of the country Phil. Would love to run our car against you and the TIC guys sometime. Global Time Attack has got their series going and they have four events this year- Big Willow, NJ, Autobahn, Infineon. Maybe we should come to Chicago?

Last edited by AQ Motorsports; 04-05-2011 at 05:36 PM.
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Old 04-05-2011, 05:37 PM   #11
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what lateral g's were you keeping in banking? keep in mind the change in vertical g's on banking. It and it's effects are often overlooked. I know you guys use to spin your Cossie plant a bit north of 9k.

Phil, the 11mm pump shouldn't have an issue pulling oil so long as the oil is higher than the standard pump and feedline is large. It's a rather simply fluids problem with a few assumptions made (of negligible amount).

Then of the added pressure on the feed from the vertical oil (pressure). Keep in mind that pipe length and bends do add loss in the system though. A big feed line is a good thing
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Old 04-05-2011, 05:50 PM   #12
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I'm pretty embarrassed to admit our datalogs haven't been monitored a whole lot lately outside of the engine stuff, but when octane report threw on a tracker we saw up to 1.88g in turn 9 at big willow on the old aero package. motoiq should have a bunch of data from superlap too but I haven't seen it yet. one of our front suspension position sensors has been broken for like 6 months now. oops.
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Old 04-06-2011, 05:39 AM   #13
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Thankd for the info guys. The cams we are going to use will be around 285 degs and about 12mm of lift.
I've been told by some Greek tuners to run 11 to 1 if only using E85. from what you guys have saidf without knowing what exactly i'm going to run , it looks safe to run 10.1
I'm not after more power up top I'm just wanting to keep the motor on boost with a GTX4294.
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Old 04-06-2011, 08:44 AM   #14
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If you have the cam card, getting rough values for dynamic compression ratio isn't hard to get. Adjustable cam gears can be factored into calcs too if given estimated range of adjustment or to more precisely build future pistons for the application (back up engine).
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Old 04-12-2011, 12:20 PM   #15
Element Tuning
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Quote:
Originally Posted by AQ Motorsports View Post

Our oiling system has held up great with just a big Moroso pan, accumulator, and Cosworth 12mm pump. At cal speedway last year we were revving to 8500 and doing like 2g on the bank. Then when the last motor came apart the bearings all looked great. The cosworth motor we used to have would rev even higher and also had no issues using their pump and pan so I'm just not convinced the cost and complexity of a dry sump is completely worth it.

Too bad we're on opposite sides of the country Phil. Would love to run our car against you and the TIC guys sometime. Global Time Attack has got their series going and they have four events this year- Big Willow, NJ, Autobahn, Infineon. Maybe we should come to Chicago?
Once I added up all the costs between the oil pan, accumulator, lines, etc I just decided it was a good chunk to put towards the dry sump. Oh and the dry sump worked like a charm this past weekend. I should have done this last season but as they say, hindsight is 20/20.

Yeah it's too bad neither of us go to the other cost but honestly it's just so expensive to do so ($12k). I may actually run a West coast event this year but we'll see if I would rather pay myself or race

Last edited by Element Tuning; 04-12-2011 at 12:28 PM.
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