Stroker / Bore thoughts?

[tdstuart]

A normal machine shop will charge $1000-$1200 to install the sleeves and unless they have done it many times I would not let them. I had a local machine shop crack a block of mine trying to install a stock sleeve so a lot bigger sleeve would be harder

Damn that’s a lot. And that’s my problem I haven’t heard anything about any of my local machine shops. Going to call them up anyway and see if any have done work on a coyote motor. I need them to check my block and see if they need to bore it or what would need to be done. Haven’t pulled the motor yet but looks like some good scoring on the side where the piston melted.

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[tdstuart]

I have been involved in some engine testing using long and short rods. After tuning there was no difference in power.

Side loading and engine longevity are the main reason for long rods in production engines. The 1.52 or so you would get from stroking a coyote will not reduce the life by any measurable amount.

I'll use the 400 SB Chev as an example since it was brought up. They last just as long as any other SB. The guys making big power with them have cam designs that take advantage of the fast pull away from TDC.

Now should we talk about offset piston pins?

So you think the 5.5L would be worth it?

 

[K4fxd]

Absolutely. Just use quality parts.

I've never used them but MMR sells a kit # 603700

https://www.modularmotorsportsracin...result&search_in_description=1&keyword=603700

 

[tdstuart]

Absolutely. Just use quality parts.

I've never used them but MMR sells a kit # 603700

https://www.modularmotorsportsracin...result&search_in_description=1&keyword=603700

So if I went to a 5.5L but kept stock cams and the same setup as I previously had would I expect a 10% hp increase

And should I piece it together or just buy their kit?

 

[K4fxd]

A stock 2 gen coyote is about 87 HP per liter so the added displacement should get you an additional 40 or so.

 

[K4fxd]

And should I piece it together or just buy their kit?

I'd buy the kit. All the components are matched, or should be.

I'm sure there are other builders that make and sell kits.

 

[tdstuart]

I'd buy the kit. All the components are matched, or should be.

I'm sure there are other builders that make and sell kits.

Alright now I just got to figure out if it’s worth it to spend the money haha

 

[K4fxd]

Alright now I just got to figure out if it’s worth it to spend the money haha

That is always the question.

Good luck.

 

[GregO]

The guys making big power with them have cam designs that take advantage of the fast pull away from TDC.

Now should we talk about offset piston pins?

Now here we have the beginning of a real discussion.
I think Smokey threw that “Use the longest damn rod as possible” crap in his book just to E’f up his competition…….

 

[Jackson1320]

I'd buy the kit. All the components are matched, or should be.

I'm sure there are other builders that make and sell kits.

There are a few but they are all 2-3x the price of mmr’s

 

[engineermike]

LS7 is 1.517, as mentioned, but doesn’t rev as high as the coyote. But apparently the modern 8000 rpm bmw s54 v8 has a rod/stroke ratio of only 1.527, making 110 hp/liter.

Stock coyote being 1.62…using the mmr 3.84 stroke crank and shorter 5.85 rod would result in 1.523. Not bad but if that’s a bit too close for comfort, the 3.80 stroke crank would make it 1.539 and still get you 5.4 liters.

 

[Decible]

I think roadcone is at 3.7x3.9 with a 3.8 whipple. Another guy was also 3.7x3.9 with a cj intake and 600+ at the wheel NA with a 8k redline. A rod ratio in the 1.5’s is fine I’ve known several high HO ls7’s in the 600+ crank with many many thousands of hard track mile with no problem with 8k redlines. It’s doable not cheap as all of those builds had some nice parts. The ls7’s were ktech builds so….expensive

 

[K4fxd]

I stopped worrying about rod ratios when we started building 7000 + RPM 5 inch stroke Harley Davidsons. Most of these were rode hard and put away wet.

 

[engineermike]

Interesting:

Stock stroke/2 + stock rod + stock compression height = 3.65/2+5.933+1.167 = 8.925.

The stock block deck height is listed as 8.937, giving it a deck clearance of .012”, which sounds about right for a stock motor.

Now…doing the same math for the mmr crank and shorter rod using stock pistons = 3.84/2+5.85+1.167 = 8.937”, giving it exactly zero deck clearance. This probably isn’t coincidence.

Mahle makes 2 different pistons for the 3.701 block. One is 1.167 (coyote) compression height and the other is 1.161 (5.2) compression height. They also are two different materials and dome volumes. I believe either would work depending on exactly which compression ratio and material you want.

 

[WildHorse]

If your stupid rich, go for it.

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