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Total Newb looking for advice with EA71 and EA81 engines...


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12 replies to this topic

#1 FormulaZR

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Posted 22 July 2009 - 12:01 PM

First, I'll introduce myself as this is my first post on these forums. I'm from West Texas and a total gearhead. I'm not really a Subie guy by nature...but I have a couple engines that I will be building up for experimental aircraft use. I'm pretty new with these engines, so take it easy with me if I use wrong terminology or state the obvious please!

Currently I am mounting an EA71 to a V-max experimental. It has a single carb and 1 intake port per head. So here's the questions:

1) The intake manifold doesn't appear to be a great design for power, what is the best intake...or intake design...for max power between 2400-3400 rpm?

2) Does anyone have any real world experience regarding head work results on this engine?

3) Who makes cams for these engines, and what would be the best grind for 2400-3400 rpm?

4) Are the pistons forged or cast?

5) What is the highest (up to 10:1) compression that these engines will safely and reliably run with, and who makes the pistons to bump the compression? Or...do you just mill the heads?

6) Are they any tips you guys can give me to help me get the most out of this engine reliably?

7) All the above questions for an EA81 (for a future engine swap).

If I left any important details out, please let me know and I'll provide as much info as I can! Also, I do have both an EA71 and EA81 currently, so I'm ready to start experimenting.

Thanks,
Zach

#2 moosens

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Posted 22 July 2009 - 04:39 PM

You'll find tons of info on the experimental aircraft sites. .... or maybe you didn't ?

Cams - Delta , not sure who else these days.

Good luck and be safe.

#3 Kostamojen

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Posted 22 July 2009 - 05:13 PM

Here is a website for RAM engines that modifies EA81's/etc. for aviation use:

http://www.ramengines.com/

#4 subiemech85

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Posted 22 July 2009 - 11:38 PM

don't expect any REAL power at those RPM ranges, you're basically lugging them!

ea71 cruises @ 3,600 smooth @4k worthless beyond 5k
Posted Image

http://jsae.jp/autot...ata_e/9-6e.html

ea81 cruises @ 3,000 not sure where it's smooth @ worthless beyond 6k, produces good power around 3,400

Posted Image

ea81 performance is with ea82 intake and carb, runs good on e85 or e10, 21 mpg

http://subaruavia.na...ne_diagram.html

RAM engines will be happy to collect your $$$ :grin:

#5 kiwi subbie

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Posted 23 July 2009 - 01:14 AM

Here is a website for RAM engines that modifies EA81's/etc. for aviation use:

http://www.ramengines.com/


It looks like ram doesnt make the supercharged ea81 with 200hp any more :confused:

#6 FormulaZR

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Posted 23 July 2009 - 07:04 AM

Thanks guys...part of my "problem" is that my application is somewhat weight critical. All of the auto engines converted to aero use are a compromise....but it's worth it to me for what I'm doing.

In stock form the EA71 will do what I need, just not quite what I want. Ideally I'd use a turbo'd EA81, but the added weight of the 81 vs 71 plus the turbo just puts me out of the weight spectrum I can handle.

I've read a little about using EA63 heads on the EA71, does this offer any gains? Also...I am wanting to mill the heads a little bit to bump the compression, does anyone know the "max" they can be milled and keep the engine happy?

I could, in theory, turn the engine up higher...up to 3800 with direct drive, or higher with a reduction drive, but I really don't want the weight of a re-drive.

#7 FormulaZR

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Posted 23 July 2009 - 07:07 AM

don't expect any REAL power at those RPM ranges, you're basically lugging them!

ea71 cruises @ 3,600 smooth @4k worthless beyond 5k
Posted Image

http://jsae.jp/autot...ata_e/9-6e.html

ea81 cruises @ 3,000 not sure where it's smooth @ worthless beyond 6k, produces good power around 3,400

Posted Image

ea81 performance is with ea82 intake and carb, runs good on e85 or e10, 21 mpg

http://subaruavia.na...ne_diagram.html

RAM engines will be happy to collect your $$$ :grin:


Sorry for the stupid question, but I'm having trouble reading that graph due to english vs japanese measurements. Does anyone have these dyno charts with HP and Ft/Lbs?

Besides, horsepower is relative...I'm looking at that torque peak around 3500. I'm going for thrust, not a fast spinning prop.

Edited by FormulaZR, 23 July 2009 - 03:12 PM.


#8 moosens

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Posted 23 July 2009 - 02:18 PM

This sounds along the lines of some current projects by other members. Please keep your info posted as I'm sure there's several of us if not dozens who want to follow this project.

I'm guessing you want the first issue 4-port 1400 heads and not the last revision 2-port which was around here in the USA for 1975 and 76 or so.

Mind keeping a running tally on expenses for this engine? I'm sure a few of us would like to know if this is in our budget.

I'm sending a PM to you .....

#9 FormulaZR

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Posted 23 July 2009 - 03:05 PM

This sounds along the lines of some current projects by other members. Please keep your info posted as I'm sure there's several of us if not dozens who want to follow this project.

I'm guessing you want the first issue 4-port 1400 heads and not the last revision 2-port which was around here in the USA for 1975 and 76 or so.

Mind keeping a running tally on expenses for this engine? I'm sure a few of us would like to know if this is in our budget.

I'm sending a PM to you .....


Got the PM, thanks. For the first "incarnation" of this I will be using EA71 stock heads, just to see. My first two steps are going to be some head work, and a cam from Delta. I'm going to start small and work up from there if the results don't suit me...

Are there any gains from using 1400 heads? If so, what are they and where did they come from? IE: better casting, or small combustion chamber, etc?

Side note, and I really need some info on this: Does anyone have any information on milling heads. IE: How much can I mill? My goal is 9.2-9.5:1 compression...but I'm wondering how much that takes and if I will have any PTV issues. Also...are there thinner head gaskets available for this engine that will reduce the amount of milling required.

Thanks again,
Zach

Edited by FormulaZR, 23 July 2009 - 03:13 PM.


#10 bheinen74

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Posted 23 July 2009 - 04:16 PM

Jerry DeMoss offered up head shaves and port services a while back
so he is the best bet for getting info.

#11 FormulaZR

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Posted 23 July 2009 - 05:33 PM

Jerry DeMoss offered up head shaves and port services a while back
so he is the best bet for getting info.


Thanks, can I find him on here?

Also, anyone know if EA81 and EA71 cams interchange?

#12 subiemech85

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Posted 24 July 2009 - 12:23 AM

IIRC, dual exhaust port heads reqire different cams due to valves being in different orientation

ea71 vs. ea81 differences: front and rear main seal, front hanger bolt, valve rocker assy, push tubes,
camshaft, crankshaft, con. rod, crankcase stud bolt, oil pan ........


std. height of cyl. head

ea71 89.6mm

ea81 90.6mm

warping limit .05mm

grinding limit .5mm

weight of engine without trans. (oil and coolant are included)

ea81 209 lbs 95kg

ea71 216 lbs 98kg

ps conversion http://en.wikipedia....i/Horsepower#PS ? 0.98632 hp

9.0 cr (Hatchback STD, DL, Sedan DL and Hardtop DL except Cal.) ea71 regular cr is 8.5
ea81 cr is 8.7

#13 Kostamojen

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Posted 24 July 2009 - 12:52 AM

If weight is your primary concern, stick with the single-port EA71/81 heads that come with the engine.




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