198 vs. 225

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kittypancake

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I'm contemplating what type engine build to do. I'm leaning (HA! LEANING! GET IT?) torwards turbo. I have a 198 + a 225 in the garage awaiting teardown. I've read a lot about 198's connecting rods being better. What's the difference? I'm not building a race car, 99 +44/100 percent street use. I'm inclined to use the 198. In short, I'm looking for opinions on which one gets the time + money.
 
The 225 rod is 6.700" center to center. The 198 rod is 7.005" center to center. The bores are all the same in all three engines. The 7.005" rod of the 198 and the 4.125" stroke crank of the 225 make for a 1.69 rod to stroke ratio. That's pretty good. It keeps the piston at TDC longer resulting in more of a "push" from combustion and it also aids in unloading the piston skirts and the cylinder walls. The 198 and 225 are both raised deck engines much like the 440, while the 170 is a low deck engine much like the 383 and 400. I'm not sure you'll see an appreciable horsepower difference between all three considering a turbo.....but like the old saying says, there's no substitute for cubic inches. Here's some really good reading on the slant 6.

http://www.slantsix.org/articles/stroking/stroking.htm
 
Off topic I know but I bet the higher revving 170 and turbo would be a really fun autoX/road course car.
 
Rug_Trucker said:
Doug Dutra recently said detonation problems with a turbo and the long rods. I am considering a long rod turbo. I have a 198 in the car now. 2 225's laying around.
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Where did you find the long rod/detonation info?
 
kittypancake said:
Where did you find the long rod/detonation info?
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Over on .org, I'm sure. It's no secret. Long rods increase dwell time at TDC which can resuly in higher cylinder pressure and therefore increase the liklihood of detonation....especially with forced induction.
 
kittypancake said:
Where did you find the long rod/detonation info?
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Dang! I have been searching www.slantsix.org and can't find it.

I was thinking of doing a long rod 198 rod, or K-1 rod engine with a turbo.

I thought I recently read a thread with a comment about that, maybe a link? I started my own thread in the boost forum just now.
 
Hay Mike, how much is that block decked in those pics?

MRL Performance said:
Build the 225 with the 198 rods, 2.2L 4 banger pistons and you will have pistons that are right at the top of the bore. Not to mention the pistons are a lot lighter, stronger and have a much thinner rings pack. These pistons are designed for Turbo applications.
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kittypancake said:
Would a turbo work well with this combination?
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IF you use the 2.2 turbo piston, like Mike pictured above, yes they will work well with a turbo. I went with the KB239, which is a non turbo piston that gives more compression.
 
Well yes and no. You can order a set of 4 no problem. But single ones are Special Order. They want to make them all the same weight. Just order 2 sets of 4 and sell the remanding 2 to someone who can use them. Use these rings http://www.summitracing.com/parts/SLP-E-562KC/

That block was decked about .040"? I dont remember, but I decked the head more and that was .060". That engine was right at 9 to 1.
 
The 225 is plenty powerful stock as is, at least mine is. It is a lot of fun to drive. the 225 has a sweet spot at about 35mph when you feel the power just kick in, it is amazing! I'd go with the 225 all day, not that the 198 is bad, I just go with what I know.
 
My Duster has turned 1 best of 10.58 @ 59mph in the 1/8. 198 stock bottom end. Open 3:23 rear. Headers, M-1 2bbl intake 318 model Holley. That was shifting without a tach, stock cam and a 3 speed manual on the column. .090 off the head, stock valves, lots of porting. Times were the same if I didn't hit 3rd gear. 215 R70-14 Kelly Chargers with 35lbs of air.

Gobs of power can be found in the cylinder head.

Fastest I've had it on the highway was 117mph and there was more pedal.

Build a 225 or go with what you have. I also have 2 225's out there to play with.
 
MRL Performance said:
Well yes and no. You can order a set of 4 no problem. But single ones are Special Order. They want to make them all the same weight. Just order 2 sets of 4 and sell the remanding 2 to someone who can use them. Use these rings http://www.summitracing.com/parts/SLP-E-562KC/

That block was decked about .040"? I dont remember, but I decked the head more and that was .060". That engine was right at 9 to 1.
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I have a 198 and am looking to use the 225 crankshaft. the link you have is to piston rings. What piston was that for? Sorry i know this is a pretty old post but i like the idea and wanted to hear a little more about it.
 
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