Dinan 4.6L Dyno - Finally

[Malek@MRF]

Originally Posted by Hujan

Interesting stuff, RG. Forgive my ignorance, but why does a longer stroke result in a smaller wrist pin? I'm not doubting you at all, but the reasons for that effect are not obvious to me.

Also, since engine work is almost certainly in my future, it would be interesting to see your recommendations/thoughts on engine work depending on different goals. For example, I've often wondered what it would take to build an S65 that could safely rev to 9,000 RPM. I assume that lighter engine components would be an important part of this puzzle (e.g., rods, valve train components), but I'm unsure what effect such a pursuit would have on bore and stroke dimensions (other than my simplistic sense that the more over-square the engine, the better it is for a high RPM performance).

Originally Posted by regular guy

I'm not 100% sure myself, but I know this was one of the compromises RD Sport had to make to get the 85mm stroke. Maybe one of the engine designer dudes on the forum can chime in with a definitive answer. I can describe what changes in the piston design on the various strokers, but I'm just not sure which one or more of these play the role in the smaller wrist pin.

I'm going to guess that it's most likely the only way to get the piston to clear the crank as it approaches bottom-dead-center. The piston dome design needs to be a minimum thickness, shape, and size to hit your target compression ratio. Under that the rings probably need to be specific sizes and distances from each other. Under that comes the wrist pin, and finally the piston skirt. Let's assume the design of everything from the center of the wrist-pin to the top of the piston dome is fixed in stone and can't change all that much. Likewise, you would need a minimum side skirt on the piston. So now if you increase the wrist pin diameter, you displace the side skirt because you can't displace the top of the piston. So the side skirt becomes longer and might have problems clearing the crank at bottom-dead-center. I know the pistons come pretty darn close because the design has a relief machined in them just to clear the oil squirters at bottom-dead-center. Or let me say this another way: with 21mm wrist pin, the side skirt might crash the crank. So to fix that, a smaller wrist pin would help prevent it by allowing the side skirt to be a little shorter.

I've got some other ideas why the smaller wrist pin might be needed, but this one seemed like the most likely in my mind. Maybe some of the engine design dudes can shed more light on it...that's my SWAG for what it's worth.

This was more than likely done for a couple of important reasons, but the first and more important reason being that the smaller wrist pin will result in a lighter bobweight which allows the engine to maintain the higher revving characteristic which is normally taken away with a longer stroke.

[s85e90]

Originally Posted by Hujan

Interesting stuff, RG. Forgive my ignorance, but why does a longer stroke result in a smaller wrist pin? I'm not doubting you at all, but the reasons for that effect are not obvious to me.

Also, since engine work is almost certainly in my future, it would be interesting to see your recommendations/thoughts on engine work depending on different goals. For example, I've often wondered what it would take to build an S65 that could safely rev to 9,000 RPM. I assume that lighter engine components would be an important part of this puzzle (e.g., rods, valve train components), but I'm unsure what effect such a pursuit would have on bore and stroke dimensions (other than my simplistic sense that the more over-square the engine, the better it is for a high RPM performance).

I would only do valve springs/ retainers and have no cocerns spinning the motor to 9k.

[Hujan]

Originally Posted by s85e90

I would only do valve springs/ retainers and have no cocerns spinning the motor to 9k.

Yeah, I suppose that's one option. But part of the goal with the engine work would be to definitively resolve, as best I can, the bearing issues. So I envision a full tear down to properly size the crank. At that point, I don't see any reason not to go with better rods and pistons. And if I'm going to do all that, I might as well bore and stroke it to increase displacement. (Then there's the cam conversation, the port-and-polish conversation, and so on.)

The stock bore and stroke is 92 mm and 75.2 mm, for a 1.22 bore:stroke ratio. If I bore it to 94 mm and stroke it to 79.2 mm, the displacement would be 4.4L, but the bore:stroke ratio drops to 1.18, so it's less over-square than a stock S65. This would seem to beget a lower redline. Thus, the question then is whether using lighter weight parts (e.g., lightweight rods and titanium valve springs and retainers) would help me maintain my at least my current 8.6k redline if not boost it to 9k despite the less over-square bore:stroke ratio.

The dream would be to have a higher displacement motor that spins higher than the stock motor and yet is actually more robust and durable than the stock motor (both due to proper bearing clearances and less kinetic stress at high RPM). It will be tough, but fun.

[1MOREMOD]

Originally Posted by Hujan

Yeah, I suppose that's one option. But part of the goal with the engine work would be to definitively resolve, as best I can, the bearing issues. So I envision a full tear down to properly size the crank. At that point, I don't see any reason not to go with better rods and pistons. And if I'm going to do all that, I might as well bore and stroke it to increase displacement. (Then there's the cam conversation, the port-and-polish conversation, and so on.)

The stock bore and stroke is 92 mm and 75.2 mm, for a 1.22 bore:stroke ratio. If I bore it to 94 mm and stroke it to 79.2 mm, the displacement would be 4.4L, but the bore:stroke ratio drops to 1.18, so it's less over-square than a stock S65. This would seem to beget a lower redline. Thus, the question then is whether using lighter weight parts (e.g., lightweight rods and titanium valve springs and retainers) would help me maintain my at least my current 8.6k redline if not boost it to 9k despite the less over-square bore:stroke ratio.

The dream would be to have a higher displacement motor that spins higher than the stock motor and yet is actually more robust and durable than the stock motor (both due to proper bearing clearances and less kinetic stress at high RPM). It will be tough, but fun.

It does sound fun but might be wishful thinking. Probably could get one good rev to about 11k now.

[Malek@MRF]

Originally Posted by s85e90

I would only do valve springs/ retainers and have no cocerns spinning the motor to 9k.

This isn't recommended or feasible. The weight is too high (pistons, rods, wrist pins). It might work out fine a few stints to 9000, but nothing reliably. Not to mention the cams don't make power past stock redline, and the 284's don't much either.

[s85e90]

Originally Posted by Malek@MRF

This isn't recommended or feasible. The weight is too high (pistons, rods, wrist pins). It might work out fine a few stints to 9000, but nothing reliably. Not to mention the cams don't make power past stock redline, and the 284's don't much either.

People spin the s65 to 8600 RPM already, I'm surprised to hear you say that pistons (OEM) are not adequate. I figure if no one is tuning the vanos profiles then cams are a given for a big HP all NA motor, but for the casual stint to 9k I don't see much more than valvetrain work.

[s85e90]

Originally Posted by Hujan

Yeah, I suppose that's one option. But part of the goal with the engine work would be to definitively resolve, as best I can, the bearing issues. So I envision a full tear down to properly size the crank. At that point, I don't see any reason not to go with better rods and pistons. And if I'm going to do all that, I might as well bore and stroke it to increase displacement. (Then there's the cam conversation, the port-and-polish conversation, and so on.)

The stock bore and stroke is 92 mm and 75.2 mm, for a 1.22 bore:stroke ratio. If I bore it to 94 mm and stroke it to 79.2 mm, the displacement would be 4.4L, but the bore:stroke ratio drops to 1.18, so it's less over-square than a stock S65. This would seem to beget a lower redline. Thus, the question then is whether using lighter weight parts (e.g., lightweight rods and titanium valve springs and retainers) would help me maintain my at least my current 8.6k redline if not boost it to 9k despite the less over-square bore:stroke ratio.

The dream would be to have a higher displacement motor that spins higher than the stock motor and yet is actually more robust and durable than the stock motor (both due to proper bearing clearances and less kinetic stress at high RPM). It will be tough, but fun.

w/out a doubt, go all out. I was simply stating what I felt was the limited means to go safely to 9k. If you're building a piece, then def yes, pistons, rods, etc.

I would love to see a 4.6 with ITB, dinan TB and cams with a built bottom end and a nice rear gear setup. Would be the perfect street car.

[Hujan]

Originally Posted by s85e90

w/out a doubt, go all out. I was simply stating what I felt was the limited means to go safely to 9k. If you're building a piece, then def yes, pistons, rods, etc.

I would love to see a 4.6 with ITB, dinan TB and cams with a built bottom end and a nice rear gear setup. Would be the perfect street car.

Gears (and a CF driveshaft) would definitely be part of the equation. I'm thinking something along the lines of a 3.45 (up front the 3.15 stock FD). A cam'd 4.6 with gears would be pretty awesome.

[SteveInfante]

Does anyone even make a CF driveshaft for the E9x M3? I think that would make a significant difference in the way it drives which is already awesome.

[BPMSport]

Very nice numbers! Good seeing you at bimmerfest. I'm sure there's some more ponies on the table

[ilikebmxbikes]

Originally Posted by Mike Benvo

Very nice numbers! Good seeing you at bimmerfest. I'm sure there's some more ponies on the table

Likewise! and thank you for coding Euro MDM and my car to accept my dog passengers! (seat belt chimes off for when the dog sits on the seat)

Im going to do as you suggested and see how the car does with 93octane.

[BPMSport]

Originally Posted by ilikebmxbikes

Likewise! and thank you for coding Euro MDM and my car to accept my dog passengers! (seat belt chimes off for when the dog sits on the seat)

Im going to do as you suggested and see how the car does with 93octane.

My pleasure.

Sounds good, I think it will help as you had -5 deg global retard on all cylinders. Not sure if targeted timing is stock though. Dante, Teddy, and DJ should get together for a pow wow soon!

[ilikebmxbikes]

Originally Posted by Mike Benvo

My pleasure.

Sounds good, I think it will help as you had -5 deg global retard on all cylinders. Not sure if targeted timing is stock though. Dante, Teddy, and DJ should get together for a pow wow soon!

Ill let you know when I bring them down next. Would be cool to get the dogs on your side of town.

[e92livin]

Always loved the Dinan stoker motors, If it wouldn't financially ass rape me I would so go that route haha.

[ilikebmxbikes]

Originally Posted by e92livin

Always loved the Dinan stoker motors, If it wouldn't financially ass rape me I would so go that route haha.

They really are phenomenal for the NA m3 owner.

I originally purchased the car with the intention to remove the stroker and swap it with the 4.0L in my 1M clone but after driving the dinan m3 around, I really fell in love with it. Turner recently posted a interlagos m3 and now I am a bit inspired to do seats, coilovers and roll bar in this car too.

[Shredicus]

Originally Posted by Malek@MRF

This isn't recommended or feasible. The weight is too high (pistons, rods, wrist pins). It might work out fine a few stints to 9000, but nothing reliably. Not to mention the cams don't make power past stock redline, and the 284's don't much either.

Malek: have you heard of any s65 owners knife-edging the crank in conjunction with lighter pistons/rods? I feel like that would give this motor a FPC-like revvability.

[squartus]

Originally Posted by Stevedotmil

Does anyone even make a CF driveshaft for the E9x M3? I think that would make a significant difference in the way it drives which is already awesome.

Yes DSS recently started making CF 1 piece drive shafts for the M3, I installed one a few months back.
Only a few pounds of weight reduction due to the massive alum adapter plate, it did take out most of the drive train lashing you get when letting off gas at low speeds and alot of the clunk etc when easing out of 1st gear. You can twist the OEM drive shaft on car with your hand and it will move half an inch back and forth due to the two piece design.
Also seems to launch a little better, more like a rubber band so does not break loose quite as quick.

That being said it took almost a month to get the right parts in with my car on jackstands, sent wrong adapter plate first then sent wrong bolts for the new adapter plate.

[8600RPM]

That's disapointinf as u remember your thread. Was like 2 pounds ssvings. Don't see that being worth it.

[Hujan]

Originally Posted by ilikebmxbikes

They really are phenomenal for the NA m3 owner.

I originally purchased the car with the intention to remove the stroker and swap it with the 4.0L in my 1M clone but after driving the dinan m3 around, I really fell in love with it. Turner recently posted a interlagos m3 and now I am a bit inspired to do seats, coilovers and roll bar in this car too.

Funny how that happens, huh? "Gonna leave it as is except for painted reflectors" quickly turns into a full-on build with a rear-seat delete and roll cage. Sigh.

Originally Posted by Shredicus

Malek: have you heard of any s65 owners knife-edging the crank in conjunction with lighter pistons/rods? I feel like that would give this motor a FPC-like revvability.

I can't speak for him, but I believe Malek has looked into this exact issue and may have something in the works. I'd imagine you'll see him post more about this soon.

[8k3]

Originally Posted by Hujan

Funny how that happens, huh? "Gonna leave it as is except for painted reflectors" quickly turns into a full-on build with a rear-seat delete and roll cage. Sigh.

You make me want to cry thinking back. I could have bought a serious P car with all the mods I've done. I started with a lowly Ford Taurus (I had nicer cars previous to that, it was always my beater, ended up driving it as a daily though for a year). i love the M but I kind of regret dumping that kind of cash into such a badly depreciating asset (Porsches hold better, need less modding). Funny thing, once you reach the point of no return, you sake F it and go balls to the walls. So I too might at some point consider a built motor such as RDport's config (I'm not enamored with Dinan's, as you can't bore their 4.6 again)