Put a rod through the block andoil pan (pics of carnage)

92bird

Registered User
First off, this was NOT a supercoupe 3.8L block, it was a 1996 mustang/base t-bird 3.8L bottom end, with police taurus cylinder heads (approx 8.6:1 compression with these heads), as installed in my old '94 SC (sold to a good friend).

See the whole story here how it began: http://sccoa.com/forums/showthread.php?t=117545&highlight=police+package

The bottom end had 140k miles in regular 3.8L N/A duty, then was re-ringed and reassembled with new King bearings, etc.

It then survived another 41k miles in stockish SC duty format (early model cam, factory '94 blower with 89 pulley). The car lives mainly at high altitude in Denver, but saw about 20 trips to various sea level or near sea level locations. Never a missed a beat, was very reliable..

The new owner of the car installed an old school dr fred .520 cam (212/218 durations). It lasted another 5k miles until we added the following this past weekend: MPX blower, new eaton rotor pack, 85mm TB/MAF 15% od, MP FMIC, kooks long tubes and true dual exhaust, and some other schwag i'm forgetting. He was running 80lb injectors, and Aeromotive stealth pump on E85.

Got part throttle trims/KAMs dialed in, WOT timing was about 26 up top, AFR's in the mid-low 11's (E85, but on gasoline scale). Since we are at high altitude, I was going to give it some more timing but we never made it that far. It threw a rod through the block and oil pan on a 2-1 downshift on our 8th WOT run with this setup. Ran like a raped ape until it blew.

We completely expected this to eventually happen on this motor.. Those powdered metal rods just were never designed to take this kind of abuse. Again, read the other thread, this motor was intended to be a temporary replacement, but the new owner wanted to see what it would do.

Surprisingly the motor help up for a long time in stockish SC form. I would not hesitate to use this bottom end and police heads combo on a stockish SC for a replacement motor.

Teardown to come soon.

Jeramie
 

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So the question is, how many times would you need to scatter one before you would not consider recommending it?
 
So the question is, how many times would you need to scatter one before you would not consider recommending it?

Note I said in a stock SC setup. It lasted 41k miles on a '95 blower/early model cam combo, and didn't break until we put $5k worth of bolt-ons and cam in it.

To clarify, I obviously do not recommend this bottom end for a cammed setup with all the bolt-ons. But the point was, it held up fine on a stockish setup.
 
it probably would have lasted a lot longer if it wasn't so lean

mid 9s would have done the job nicely and made more power (gasoline scale)
 
it probably would have lasted a lot longer if it wasn't so lean

mid 9s would have done the job nicely and made more power (gasoline scale)

No way.. I started out with mid 10's afr on this motor for the first pull, and 11.5 afr pulls WAY harder, night and day difference..

Just so we are on the same page, the car is running 11.5 AFR on a gasoline scale calibrated wideband. This would be .78 Lambda, or 7.6:1 on a proper E85 scale.

All the local terminator cobra E85 guys, and including my non-intercooled M90 GTP are running in this range. My GTP made max power on the dyno at 12.4 AFR, but I run about 12.0-12.1 AFR daily on the street (.81 Lambda), and have been for the past 3.5 years. Plugs look good, no knock sensor activity, and no blow head gaskets/chipped pistons, but the GTP only sees 10-11 psi.

Jeramie
 
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it probably would have lasted a lot longer if it wasn't so lean

mid 9s would have done the job nicely and made more power (gasoline scale)

OK, in the spirit of being open minded, is there some reason you feel it would make more power at this level? Everything I can find on the internet from googling "E85 AFR boost" shows I am right on around .78 lambda..

I know high boost turbo guys get a little better results running richer, but even then they are targeting mid to high 10's (around .72 lambda)

Jeramie
 
Putting a rod through the block has nothing to do with afr's and alot to do with the design of the motor.

It does have something to do with AFR's, but not directly. The problem is that with the NA motor there just isn't any margin of safety. Yes, it will work for awhile, but sooner or later detonation is likely to rear it's ugly head and when it does, you just don't have anything to back you up. Ford didn't go through all the design effort in redoing the block/crank/etc. for the SC just because they were bored. They did it because they needed to have a margin for safety in running the motor with a supercharger.

I would say that Jeremie running the NA shortblock in his SC is kind of like running a stock bottom end SC motor at 20lbs boost. It will hold up, we've proven that, but where's the margin of safety? There is none.

Due to the fact that the #1 reason for any motor failure in these cars is tuning, I venture to say that anything you can do to increase your margin of safety rather than decrease it, is a good thing.
 
I also got to thinking, this motor endured some audible detonating a year ago when it was taken to see level. The new owner didn't have his laptop to put a less aggressive tune on it. I'm thinking this motor may have already been hurt from rattling a few times prior. Generally, i would have thought that .78 lambda on a high octane fuel, 26 degrees max timing, and well intercooled at 15psi at high altitude in a cammed car should have been ok.. And it clearly is for other sc guys up here.

Its very difficult to get e85 to detonate, but as David said we just had no margin of safety. All it takes is a glitch in the computer or not a perfect transition in tables.

Anyhow, both me and the new owner got our moneys worth out of that wimpy mill. Steve is in sales and racked up over 40k miles in 2 years on it. Honestly, there have been many guys who spent far more, and gotten far less from their motors.

Time for something bigger and better, the question is what route to go?
 
A nicely built SC motor, stock crank, H beam rods and forged pistons should do you well....Unless you want to try out the 4.2 setup
 
A nicely built SC motor, stock crank, H beam rods and forged pistons should do you well....Unless you want to try out the 4.2 setup

Steve (the new owner of this car) has a 95 SC block and brand new (not reground) ford 4.2 crank that he bought a long time ago in anticipation of this happening.

I'll be helping him assemble the new motor. I think the plan is gonna be long H-beam rods, and forged pistons in the 9.5:1 range. He already has all the goodies, kooks long tubes, all magnum powers products (mpx, FMIC, 25% OD if desired), big injectors, pump, etc..

He would be happy with upper 300 rwhp range, and thrilled with 400rwhp. If we can achieve that goal without going to a stupid radical cam.. something that works well with a 2,500 rpm stall converter. Street performance is priority over track.. At this point, going 4.2 should result in the same cost, or slightly cheaper than the 3.8 route, as he already has the 4.2 crank, and we do not have a serviceable 3.8 SC crank to work with.

Jeramie
 
With a high lift cam and good flowing heads it seems with the MP suff people have been making id 300rwhp. 400 is a stretch using the m90 without doing something non out of the box. At least from what Ive seen
 
With a high lift cam and good flowing heads it seems with the MP suff people have been making id 300rwhp. 400 is a stretch using the m90 without doing something non out of the box. At least from what Ive seen

In theory a properly built 4.2L should be able to eclipse 400rwhp on E85. 375rwhp (actual rwhp, not imagined or corrected for altitude, etc.) was pretty much a slam dunk on 93 octane.
 
In theory a properly built 4.2L should be able to eclipse 400rwhp on E85. 375rwhp (actual rwhp, not imagined or corrected for altitude, etc.) was pretty much a slam dunk on 93 octane.

Very nice.. Sounds like he could easily find 400 rwhp on a local Denver SAE corrected dyno then, on the Corn..
 
eth is alcohol which has different properties than gasoline, with alcohol typically richer = more power, in my experiences i've found most boosted e85 engines to make max power in the low 10s (gasoline scale), by richening beyond that you don't reduce hp but you do reduce acceleration rate as the engine gets 'bogged' by the fuel, same as spraying too much methanol

it looks like dalke caught on to where i was going with that, on an engine thats prone to failure (and expected) you sacrafice a little to increase reliability, i'd venture a guess and say that if she was a tad richer we wouldn't be having this discussion

No way.. I started out with mid 10's afr on this motor for the first pull, and 11.5 afr pulls WAY harder, night and day difference..

Just so we are on the same page, the car is running 11.5 AFR on a gasoline scale calibrated wideband. This would be .78 Lambda, or 7.6:1 on a proper E85 scale.

All the local terminator cobra E85 guys, and including my non-intercooled M90 GTP are running in this range. My GTP made max power on the dyno at 12.4 AFR, but I run about 12.0-12.1 AFR daily on the street (.81 Lambda), and have been for the past 3.5 years. Plugs look good, no knock sensor activity, and no blow head gaskets/chipped pistons, but the GTP only sees 10-11 psi.

Jeramie
 
A leaner fuel mixture of E85, acts more like gasoline. a richer fuel mixture of E85 acts more like alcohol. The main change being flame front burn rate.

3.8 heads and manifold for an SC to not lend them selves to overly safe running at the edge. This because balance among the cylinders is not particularly good. Thus total A/F on one bank at 11.5 doesn't mean 11.5 at each cylinder, nor at the other bank.

Detonation needs a very specific environment in the combustion chamber to occur. E85's high latent heat of evaporation robs the chamber of the heat needed for detonation. This more so than the octane is what is makes it difficult to detonate on E85. Run richer, and you also get faster burn rate, allowing less timing advance, which cuts the other leg out from detonation, and that is time. Detonation is formed from pressure and heat over time. Pull out the heat, and decrease the time, and you have a wining combination.

That said once you dial in for all that, if you loose it, you could have an issue. loose fuel pressure so AFR raises up and you loose the fast burn rate. Fuel filter fail and let some particle block a signal injector in the rail, and bang, that cylinder is gone.

I never got to play with it fully, but I did make more power at 11AFR vs 12AFR on E85. I would have preferred 10.7. I know lots of blown cars are running 12.5 on E85, but those simply do not have the same issues we have with our motor design.
 
Thanks to all for the explanation.. So what you are saying is the sc combustion chamber benefits from an overly rich ethanol mixture versus say a vehicle with a more efficient chamber, such as an 03/04 cobra head? wonder of my gtp would have responded the same way if i went that rich?
 
Thanks to all for the explanation.. So what you are saying is the sc combustion chamber benefits from an overly rich ethanol mixture versus say a vehicle with a more efficient chamber, such as an 03/04 cobra head? wonder of my gtp would have responded the same way if i went that rich?

Our motor does not have a combustion chamber design that is as ideal as what is available in your GTP. Designs like in the more current engines are known as high swirl or fast burn designs. These promote a more homogeneous a/f mixture in the combustion chamber.

Our intake manifold design also limits the flow capabilities of our heads, allowing us to see higher boost pressures without the equivalent power. I.e. 20psi on a well constructed 4.6 motor will make much more power (with all the supporting mods) per cubic inch than our motor will.

As far as overly rich... well that depends. There isn't a lot of science on E85. Most of the knowledge comes from a very recent (relatively) sae paper analyzing E85 in a single cylinder motor. This paper indicates that theoretically you should see more efficient combustion, thus more power, running E85 at a richer than typical mixture, with less timing advance than you would otherwise need with gasoline. Most of those that run E85 around the leaner max power spec also tend to run fairly advanced timing, without ever trying it any different way. Not all cars respond the same, but in theory, those Cobra guys running 12.1 AFR on E85 are not really taking complete advantage of what E85 should be able to do for them.

p.s. A lot folks don't try to go richer because their fuel system won't support that. We are used to big fuel injectors because of how hard we push our v6 motors. V8 guys still are pretty conservative on their fuel systems, in general.
 
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