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how many 7 liter strokers are out there????

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how many 7 liter strokers are out there????

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Old 02-05-2018, 01:06 AM
  #46  
Rob Edwards
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There's Simard's 7 liter, there's Todd Tremel's 7 liter, and there's parts of a 7 liter motor that Joe Cain owned for a while and has sold. Those are the only 7 liter motors in existence that I'm aware of.
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Old 02-05-2018, 02:30 AM
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Todd found turbos and never looked back.
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Old 02-05-2018, 05:32 AM
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Originally Posted by GregBBRD View Post


Any idea of how many hours/miles this engine has on it?
I do not know, a few races I suppose. How many cracked 7L engine blocks have you put into you scrap box? Exactly where do they crack?
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Old 02-05-2018, 06:47 AM
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If we go back in time, it wasn’t just wet sleeve motors cracking it was just strokers. Back then if you exclude Bob Devore & Co, there was no wet sleeve engines. I made the claim, I do say claim because I can’t prove it, that is, that mass forces were cracking the blocks. These were engines that had cracks appearing around the crankshaft web.

I said (at the time) I planned to reduce these forces by reducing the using a Honda rod journal sized crankshaft. I had that made and it’s bob weight was 1594 grams. I also reduced the stroke to 3.55” versus the nominal 3.75”. Unfortunately I got into a bad accident and sold that project so I didn’t see it through. Now we have take two. More on that later.

I’ll just make a point about testing, we can’t afford to truly test any product or project like an OEM can, it’s just impossible. If you recall back when Mark Anderson had a few write ups in Excellence and he was blowing up motors due to rod bearing failures. We (the outsiders) were told the engine even had dry sump. Well it wasn’t till about a decade or so later that we learned it was only two stage and that you need a very large oil storage tank to compensate. Chances were that the engine was running dry from oil starvation. We now know that the 928 pumps extreme volumes of oil at very high pressures, hence the need for a very large scavenge pump. So in the early days, when there was so much talk of drilling the crank and using 360 degree main bearings we know much more these days.

‘’You mention the the 944 block, we’ll we know that Porsche then raised the level of the aluminium in the water jacket. There is far more metal in that block. So maybe the 944 was too small to start with, maybe it had something to do with the inherent vibration produced by 4 cylinder engines?

I would also say there is problems with almost every major engine mod on the 928. A lot of these problems are execution risk, that is the risk that the operator ***** it up. Even with Nicasil there is potential for problems with the fuel purity and delamination of the Nicasil especially given that the Alusil is a poor parent material to attach Nicasil due to its silicon content. Silicon doesn’t conduct electricity as such the atomic bonding can be problematic.

You can try piston coating, yes some 944 people has success, is it success in the moment or will it be short lived? You can thin wall sleeve the block with cast iron sleeves. Even the 991 models are getting that done now. Porsche’s current models still have bore problems. Execute that properly and you will probably have success. Wet sleeves are riskier, but I think with light components and a grout filled block the risk is present but hopefully controllable.

For myself, my sleeves only have 95 mm exposed to the water, the remaining length is all to be grout filled. So that means 50 mm of the bore is filled with either parent material or epoxy and should be stiff. It needs to be stiff as any flex will end badly. The components are light and super strong with a bob weight around 1500 grams. Time will tell.......


Originally Posted by GregBBRD View Post
Personally, I believe that when the original liners are machined away and additional material is removed for a larger liner in the extremely brittle Alusil block, most of the strength of the crankcase is taken away. It's not a matter of if the crankcase is going to crack...it's just when. (If you spend the time looking at a cross section of a crankcase with the liners removed, the weakness becomes very obvious.) Interestingly enough, Porsche tried stock sized removable liners on the 944GTR engines and every crankcase cracked before the end of testing. They were forced to completely abandon the Alusil material and recast a different crankcase in an aluminum alloy.

I just had a client schedule a 60,000 mile service on one of my 6.5 liter engines. I have another client with a 600hp version of one of my 6.5 liter engines that has over 30,000 miles on it.

These "tiny" 6.5 liter engines are extremely reliable, for me.
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Old 02-05-2018, 12:50 PM
  #50  
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Originally Posted by Strosek Ultra View Post
I do not know, a few races I suppose. How many cracked 7L engine blocks have you put into you scrap box? Exactly where do they crack?
┼ke
I've never been brave/foolish enough to remove all the material required to install liners big enough to make 7.0 liters.

I knew better, after the failures from the 944 GTR program.

With Mark Anderson's 6.5 liter race engines (with stock liners), we had two blocks crack.

The cracks are from the main bearings into the webs. Not sure where the cracks start, but I have always assumed that the cracks originate from the main bearings an propogate from there....like they do with thrust bearing failure.

Seriously.....take a close look at one of these blocks and just calculate the amount of structure that needs to be removed to install a 109mm cylinder...and look at the amount of material that would be left.

Combine this with the fact that the Alusil material is extremely brittle.

It amazes me that engines in this configuration make it past the break-in period!
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Old 02-05-2018, 01:54 PM
  #51  
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My 6.5 is 100% daily drivable without any worries. I can't see any reason to push the comfort zone of reliability for the sake of a bit more power that most can't use anyway. I guess one with really deep pockets could consider building a 1 hour motor or a 4 hour motor for those special events.
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Old 02-05-2018, 04:15 PM
  #52  
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Originally Posted by Jim bailey - 928 International View Post
Zero ... running I believe. The 6.5 liter is the common size that can be built without removing the none removable cylinders and installing some other type of cylinder. That is a 104 bore + - and 95.25 mm stroke. With 5.85 "Chevy rods" .
I believe that Catorce's engine is a 7.0 liter "style" engine. It has apparently ran on the dyno for break-in and a few power pulls that lasted a couple of seconds. No real testing, where the throttle is held at WOT at 6,500+ rpms for 20-30 seconds (like what really happens in a track car.) AFAIK, he now has no intention of running this engine on the track.....maybe some Vintage Car stuff, where he will cruise around the track. Apparently no PCA or POC stuff, where performance can be measured versus what others are/have been doing.

Smart man.
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Old 02-05-2018, 04:30 PM
  #53  
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Originally Posted by GregBBRD View Post
AFAIK, he now has no intention of running this engine on the track.....maybe some Vintage Car stuff, where he will cruise around the track.
You still cannot be serious with this BS, can you?

If you could bring Mark A and the Zombie to Road America for a vintage race, there are a couple if PCA 911's that would mop the floor with him (he's very familiar with one of them already).

Maybe vintage racing is a bunch of parade laps in your neck of the woods, we tend to take them a bit more serious around here, watch the tack on the first car, not exactly lugging around at 4k RPM, is he?


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Old 02-05-2018, 04:34 PM
  #54  
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Where is the snow?
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Old 02-05-2018, 09:16 PM
  #55  
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Originally Posted by BC View Post
Todd found turbos and never looked back.
Talked to Todd at Erik's last summer about intake manifolds, and he mentioned he may drop the turbos and go NA at 8,000+ RPM.

​​​The size of the engine will remain a secret.
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Old 02-05-2018, 10:59 PM
  #56  
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Originally Posted by GregBBRD View Post
I believe that Catorce's engine is a 7.0 liter "style" engine. It has apparently ran on the dyno for break-in and a few power pulls that lasted a couple of seconds. No real testing, where the throttle is held at WOT at 6,500+ rpms for 20-30 seconds (like what really happens in a track car.) AFAIK, he now has no intention of running this engine on the track.....maybe some Vintage Car stuff, where he will cruise around the track. Apparently no PCA or POC stuff, where performance can be measured versus what others are/have been doing.

Smart man.
I'm not sure what kind of mileage you get out of dissing my motor whenever you get the chance, but I'll play. When I get around to it...WHEN, not if, the car will definitely see the track. That's the whole point of it. That's why I restored a race car. Right now, I am moving, and building a 7000 square foot shop on the property. When I am done, I will finish the Devore car and then you'll get to see it run on the track. There is no timeline on this other than it will get done when it gets done.

I don't think I would have the time to run a full season of events, because like I said, I am busy, and I am constantly buying other cars. The fact that I don't run a full season means nothing, other than, as I said, I'm busy.

I really don't give a shyte if the motor explodes, I will just write another 55K check and have Carl build it again. But it won't, and I'm not worried, so you shouldn't be either.
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Old 02-06-2018, 03:45 PM
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Originally Posted by SwayBar View Post
Talked to Todd at Erik's last summer about intake manifolds, and he mentioned he may drop the turbos and go NA at 8,000+ RPM.

​​​The size of the engine will remain a secret.
Well, he has over 1100 hp now from turbos. That may need to be a big engine.
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Old 02-06-2018, 05:21 PM
  #58  
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Hopefully I can guide us back on topic,

from the discussion it seems that the wet liner approach is a step further than a dry liner solution.

Larger capacity does appeal to me but there is not a lot of information being shared to help drive forward more builds- a more open source approach might help give people confidence to attempt more builds adding to the overall development of the engine.

Reducing the mass of the rotating parts must help reduce overall forces on the block which could help with perceived weaknesses in the block. More information on this would be very interesting.
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Old 02-06-2018, 07:33 PM
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Originally Posted by Marti View Post
Hopefully I can guide us back on topic,

from the discussion it seems that the wet liner approach is a step further than a dry liner solution.

Larger capacity does appeal to me but there is not a lot of information being shared to help drive forward more builds- a more open source approach might help give people confidence to attempt more builds adding to the overall development of the engine.

Reducing the mass of the rotating parts must help reduce overall forces on the block which could help with perceived weaknesses in the block. More information on this would be very interesting.
I would think that weight would be a better focus. but that is just me.
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Old 02-06-2018, 09:17 PM
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Originally Posted by Marti View Post
Hopefully I can guide us back on topic,

from the discussion it seems that the wet liner approach is a step further than a dry liner solution.

Larger capacity does appeal to me but there is not a lot of information being shared to help drive forward more builds- a more open source approach might help give people confidence to attempt more builds adding to the overall development of the engine.

Reducing the mass of the rotating parts must help reduce overall forces on the block which could help with perceived weaknesses in the block. More information on this would be very interesting.

The crankshaft, because of its length and cylinder head offset, turns out to be pretty heavy. And it is that mass that pounds on the block. Certainly, extremely light reciprocating components would reduce the required mass of the counterweights, but a crankshaft anywhere near 50 pounds is probably not possible, unless reliability is sacrificed. 55 pounds might be obtainable.

Mike Simard certainly recognized the "issue" with removing the stock cylinders and boring the block to accept the 109mm cylinders that he made. The amount of material that remains is frightening, from a pure structural point of view. We talked/debated this subject quite a bit. To partially compensate for the loss of this structure, he made a beautiful billet piece that acted as a stiffener for the main bearing cradle and improved on the studs that held the cradle to the block. I'm not sure this engine has been run enough to know if these pieces were enough to prevent the very brittle upper section of the crankcase from cracking. Time is the only way to find this out.

Porsche tests extensively for reliability....looking for structural defects and changing the design of pieces to compensate, should changes be required. I doubt, very seriously, if any of the 7 liter engines that have been created would last for more than a couple of hours of this process....there simply isn't enough material in the crankcase to keep cracks from forming in the brittle material.

As pointed out by Slate Blue, the 944S engines and the 968 engines were significantly strengthened in the crankcase webs (bottom of the cylinders) to help with the pounding from increased rpms that the 4 valve head allowed/required. This change was the result of problems found in testing the prototype engines and from lessons learned in the 944 GTR program. (The four cylinder 3.0 crankshafts are also very heavy, BTW.) This was done to strengthen this area and keep the block from cracking.
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