E85 High Compression Build

[PolloLoco]

This thread is not meant to discuss the politics, economics, environmental issues, etc. of E85. I don't care what you think about corn, capitol hill, or hippies, we can discuss that in another thread. I care about the performance value of E85.

In order to take advantage of E85 the engine must be built to a high compression ratio. Some good info I've found on E85 for performance:
http://members.tccoa.com/392bird/e85.htm

FrankZ and 1bolt seem to know the most about this. FrankZ for his interest and later unsuccessful use of E85 and 1bolt for his interest in a high compression build.

First a conversion kit is necessary to adjust the A/F ratio, available sources are:
http://www.fullflexint.com/
http://etechmn.com/
http://www.change2e85.com/ - I've read somewhere that this automatically adjust the A/F ratio based on fuel blend, can anyone confirm this?
http://www.e85conversionkits.net/- this one has a dial so I assume that it does not automatically adjust the A/F ratio for you
http://www.eco-flex.us/Default.htm
http://flexfuelus.com/ - not available for Jeep 4.0

Most vehicles built since the late 80's have ethanol compatible fuel systems so my 97 TJ is a worthy candidate. It's also a worthy candidate for building a stroker .

My plan so far is:
Crankshaft 3214723 12CW 66lb 4.2L
Connecting Rods stock 6.123" 4.0L
Pistons KB945 +0.060" 11.38cc dish
COMP cam 68-231-4
Head Gasket Mopar/Victor Reinz 0.043"

I will bore out the cylinders 0.060" and mill the deck to 0.

This gives me the following results form the Stroker CR Calculator:
SCR: 11.09
DCR: 9.66
Quench: .043
The above assumes a combustion chamber volume of 56.7cc, not the default 58cc of the calculator. Looking around I have found that 56.7 is more appropriate and inputting a smaller value here increases SCR & DCR so in reality it may be less. I could lower the combustion chamber volume, increasing the compression ratio, by decking the head which might be worth considering.

My goal is to build a high-compression, low end torque-strong motor that doesn't run the risk of burning too lean. I feel that I am on the right track here. I would like anyone to share their experiences with E85 or their opinions of my current path.

[mendelmax]

Wouldn't it be worth to lower the CR a bit to be still able to run on premium fuel? It would help in case of E85 availability problem (AFAIK not all gas stations have it in US yet, or am I wrong?)

On the other hand, I'm not 100% sure if 9.66DCR isn't too high, even for ethanol. It seems to be too much, and it would really suck to build an engine that can't be run on the available fuel. I'd rather drop the CR a bit and be on the safe side. But that's just me.

[PolloLoco]

Wouldn't it be worth to lower the CR a bit to be still able to run on premium fuel? It would help in case of E85 availability problem (AFAIK not all gas stations have it in US yet, or am I wrong?)

On the other hand, I'm not 100% sure if 9.66DCR isn't too high, even for ethanol. It seems to be too much, and it would really suck to build an engine that can't be run on the available fuel. I'd rather drop the CR a bit and be on the safe side. But that's just me.

I've read sources that say that E85 can be run as high as 16:1 CR (I assume static). That's just ridiculous, that's diesel CR levels. I've also read 14 is a sweet spot. I've also read that 11-12 is good, and that's what I'm aiming for.

The stock block deck height is between 9.450" and 9.456". If I were to not deck the block at all then I would get:
block deck height = 9.450", deck clearance = 0.0265", SCR = 10.44, DCR = 9.1, quench = 0.0695"
block deck height = 9.456", deck clearance = 0.0325", SCR = 10.31, DCR = 8.98, quench = 0.0755"

With those number I might be able to get away with premium, until I remember that I live at 200 feet above sea level and will drive my Jeep on the beach.

There's the fact that E85 has less energy per volume than gasoline. There's also the fact that the A/F ratio for E85 is less than that for gasoline. With the combustion of the extra fuel, albeit less chemical energy, more energy is released because of the presence of more fuel per every part of air over weighs the drawback of less energy per volume of fuel. That is why people experience more power when running E85 in their vehicle. I'm trying to capitalize on this with the added benefits of running a higher compression ratio.

[mendelmax]

Well, 16:1 static may be whatever dynamic. That's the thing that you don't know. Since it was written when considering performance engines, we must assume these were designed as high-revvers, with very long intake durations. Also remember, that these engines probably had aluminum heads and were designed to operate at lower temperatures (the second problem can be fixed with thermostat, but buying HESCO head is quite a lot of $). They may also had some perfect chamber polish, or ceramic coat on it- that you don't know for sure.
I'd still consider 9.0-9.2 DCR range, since we know people on this board can run strokers on premium with 8.5:1.

Also, Id rather deck the block as much as possible and use the thin gasket instead of shaving head- it's always easier to lower CR later by higher gasket in case if anything goes wrong.

[PolloLoco]

Are Hesco heads really all that?
viewtopic.php?f=15&t=56#p353

SCR doesn't mean a whole lot, you're right. The 4.0 cylinder head design may be inferior to others. Many other vehicles can run 87 octane gasoline with higher [advertised] compression ratios. Is it the DCR or the cylinder head design that makes the difference? Both?

I could easily lower my DCR by using a different cam. The Crane 753905 with the rest of my recipe the same yields a DCR of 8.99.

[mendelmax]

Well, the 4.0 combustion chamber design is virtually over 50 years old, so I assume that's the main problem in comparison to modern DOHC heads (not too much aerodynamics during design process I suppose).

The cast iron also conducts temperature undoubtedly much slower than aluminum does. Now the thing that may lower the differences is what I would highly suggest to do- polish the chamber walls to eliminate the hot spots, and enable better air movement around the walls. It can help some, and can't hurt, so I guess it's worth trying. It does take a hell lot of time though. I've already spent over 6 hours on a single chamber, and it's not ready yet.

[PolloLoco]

Next subject: fuel injectors.
Ford 24 lb seems to be the standard for a stroker. What do folks use for a 4.7? I read from someone's post that 27 lb was too much for their stroker. To deliver extra fuel I'm thinking 27 lb would be good for me, but maybe I'll need bigger injectors. E85 will require 30-50% more fuel, might was get that done with bigger injectors than an add-on box that lengthens the injector time, or use the combination of the two.

[Plechtan]

If you want to back up a little, Hesco does make an aluminum head, since it is aluminum you can weld on it and modify the shape of the combustion chamber if you want.

[mendelmax]

I would use a combination of larger fuel injectors and adjustable fuel pressure regulator. I used an adjustable FPR in my stroker and it makes life much easier. Not only you can easily fine-tune the dose, you can also have impact on injector duty cycle etc. And it's easy to change between different pressure injectors. For example this week we have changed 39PSI injectors with 49PSI ones. Just a little nut turn and the rail works flawlessly.

For some the 22.5LBS injectors work fine (I use them myself), so I guess 27lbs with FPR should be enough

[Plechtan]

The e85 stuff looks interesting, I am in the middle of my own build so i don't have a lot of time to look into it. Racers have been using methanol for years, and e85 seem to be almost the same.

Keep us posted on how it is going. You could start a thread in the "Projects" section

[mendelmax]

Racers have been using methanol for years, and e85 seem to be almost the same.

Saying that methanol and ethanol is almost the same is just like saying that cherokee is almost the same as Hummer H3.

[PolloLoco]

Keep us posted on how it is going. You could start a thread in the "Projects" section

Yeah, I'll do that when I get started. Happy anniversary to me, it's day 365 in Iraq! I still have 143 more days, that's what I get for extending my deployment. That and extra $$$ for the Jeep.

So yesterday I decided two things:
1. I'm going to go for a military theme to the Jeep, OD green and such.
2. I'm not going to pull out the current engine and deadline the Jeep but rather I will get another 96-98 block and work from that.

[1bolt]

E85 stroker builds are a favorite subject with me, a few years back several of us had discussions on NAXJA and the email list side of strokers, where many of the facts about E85 were figured out and a whole lot of bullshit was flung around.

To get on topic I think the best most flexible way to meet E85 compression ideals is a turbo or SC, both are adjustable to some degree. Allowing the dynamic compression to be changed without major rebuilding and machining.

I'm still interested in seeing if there are some flat top chevy (or other OEM) pistons/rods out there that would be domed (just above deck height) in a 4.0 block with 258 crank.

One truly outside the box possibility was using a 232 crank, I'd have to track down the thread but the jist of it was that you stroke slightly less than a 258 crank but more than a 4.0 crank, this puts the stock 4.0 piston just proud of the hole. For a large compression increase, at low cost.

I think it nets 4.2L and somwhere around mid 10's compression this might not seem that exciting when you can get 4.6 with a average stroker, but the goal isn't necessarily displacement at all cost, a stroker 4.2 that has superior quench (less than gasket thickness) and very high compression might conceivably out perform a 4.6 stroker, and do it for dirt cheap.

Dirt cheap because you could build one without decking the block, or buying pistons, just find a good stock 4.0 candidate, find a free 232 for the crank and swap parts. You could drop the crank without even pulling the entire engine apart. If you've got a decent 4.0 with good cross hatch and compression. Stab in an RV cam for the higher dynamic compression and you'd have the mother of all junk yard strokers, just by dropping the oil pan

[PolloLoco]

E85 stroker builds are a favorite subject with me, a few years back several of us had discussions on NAXJA and the email list side of strokers, where many of the facts about E85 were figured out and a whole lot of bullshit was flung around.

To get on topic I think the best most flexible way to meet E85 compression ideals is a turbo or SC, both are adjustable to some degree. Allowing the dynamic compression to be changed without major rebuilding and machining.

I'm still interested in seeing if there are some flat top chevy (or other OEM) pistons/rods out there that would be domed (just above deck height) in a 4.0 block with 258 crank.

One truly outside the box possibility was using a 232 crank, I'd have to track down the thread but the jist of it was that you stroke slightly less than a 258 crank but more than a 4.0 crank, this puts the stock 4.0 piston just proud of the hole. For a large compression increase, at low cost.

I think it nets 4.2L and somwhere around mid 10's compression this might not seem that exciting when you can get 4.6 with a average stroker, but the goal isn't necessarily displacement at all cost, a stroker 4.2 that has superior quench (less than gasket thickness) and very high compression might conceivably out perform a 4.6 stroker, and do it for dirt cheap.

Dirt cheap because you could build one without decking the block, or buying pistons, just find a good stock 4.0 candidate, find a free 232 for the crank and swap parts. You could drop the crank without even pulling the entire engine apart. If you've got a decent 4.0 with good cross hatch and compression. Stab in an RV cam for the higher dynamic compression and you'd have the mother of all junk yard strokers, just by dropping the oil pan

Ah hah! I finally ought your attention! Now you can't ignore me

Maybe I'm thinking about this the wrong way. I'm thinking conventional stroker then planning on high compression, your ideas start totally from scratch. A supercharger could be a very real way to go about this. I have ordered my KB945 pistons but I wonder if I could cancel that. Maybe I'll just continue with my current plans and add a supercharger. I'm mostly concerned about piston to valve clearance. If I got 1.7 roller rockers, zero deck, COMP 68-232-4 and the KB945 with the shallow dish I would have .449 and .506 inches of lift intake and exhaust, would that be cutting it close?

[1bolt]

Honestly valve clearance would be the first thing to check on a build no ones really done before In other words I have no hard facts to give you, I think at .5" lifts the AMC I6's valves are still fairly far up in the combustion chamber but very few in the Jeep I6 world are running any sort of domed piston, or even for that matter flat tops.

Next time I am playing with the flow bench I will ball up some clay lay a head on it and see how thick the clay is between the deck and where the valve dented into it at high lifts.

I know from looking at it that the valve is still pretty far up in the chamber at .5" but that's just the MK I calibrated eyeball.

I think approaching from a fresh direction with E85 will give the best build... But I'm also confident that a typical budget stroker with fairly high compression and no special lengths gone through to lower it, should benefit greatly from the better fuel.

Think I'm going to have to move this thread over to performance tech...