Thread: Cubic Inches = Ahead In The Game

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So, I should be able to run a tight squish????? My most trusted motor guy died a couple years back, sure wish I would have paid more attention when he was giving lessons !!!!!!!

ahh bring it on dave i know how ya feel same thing here.. had a guy been doing it since he was 16 just died last year was in his 70's damn smart!......

Ok, so you say that its not possible to make a small displacement motor scream on the cheap? Then theres an Easy way to figure this one out. Everyone take a motor that they have a preferance too. Assemble that parts needed for a good "go fast" motor and do it at the cheapest possible. Links would be a plus also. I personally would post a few choice parts for the 4.0L/4.2L but clifford performance seems to be offline. But anyway, theres only a few things that can change a motors HPand Torque ratings. Compression, Head design, and flow. I dont remember who said it but someone said "A motor is a big air pump". Well, lets see who can make the best theoretical motors on the cheap. Me, I'll be back tomorrow with the famed 4.5L AMC/Chrysler I6. And yes, they can be built on the cheap And get good mileage to boot

Originally posted by Dave Severson
Well this seems to be the place for a stroker motor question....On a long rod stroker motor I understand about the long rod keeping the piston at TDC longer. Which would be preferred, a dished piston with a small cc head, or a flat top with a larger cc head?? Or does it even matter??? I was wondering if it matters for flame travel and mixture burn.. What squish would you want this set up at???? Thanks

Dave, On short rod vs. long rod engines:

Short rod engines, in theory, can be run with more compression than a long rod engine. The reason is DWELL time. On the short rod engine, the pistons spends less time at the top of the bore therefore the mixture doesn't have as long to be exposed to the heat that brings on PREIGNITION. On a long rod engine, (if the mixture starts burning too early), it dwells at the upper end of the stroke long enough to let cylinder pressure build up too high. The trick to each engine is timing. A short rod engine will use more timing because the fire must be started soon enough to have adequate time to burn the mixture for the power stroke. The long rod engine will use less timing because if you start it too early you have DETONATION.

The bad thing about a short rod engine is the acute angle of the rod. The pistons on a short rod engine push extremely hard on the thrust side of the bore. This in turn causes the cylinders to become "egg shaped" wearing out the bore extremely quick.

On pistons and heads:

The flattop piston will make more power at the same compression level. Angle milling heads is even better than a dome because a dome hinders flame travel. Heads should be kept with a smaller chamber for better mixture and combustion. You can run a small CC head, but don't use soup bowl type pistons. A reverse/inverted dome piston is much better. You can run higher compression with a flattop or inverted dome if you set your quench area up right. The best quench area is between .037-.039". The way it works is when the piston comes up, it squishes the air/fuel mixture from the flat part of the head and the piston causing a whirl wind type action to happen. This mixes the air and fuel better for a better burn. The D-Shaped pistons are flat on the flat side of the head and the combustion side is inverted creating a bigger chamber. You get a more efficient burn.

Hope this helps Dave...

Originally posted by lt1s10
dont count on it. you're not gonna hook up but so much HP on st. tires.

and on top of that I have heard thats its frightning to corner on a wrinkle wall drag tire at 1g with 15 lbs air!!!

It does, Fever. Helps a lot. Reinforces what I thought about a long rod motor and which would be the best piston. As I said in another post, my #1 engine guy died about a year ago and I should have payed closer attention when he was giving lessons!!! Figured I'd better get the plan right before I started buying parts. Appreciate the help!!!!

Originally posted by shawnlee28
and on top of that I have heard thats its frightning to corner on a wrinkle wall drag tire at 1g with 15 lbs air!!!

like riding around on 2 flats.

Thanks Denny, I'm going to keep that one!!!

Good article Denny. Pretty technical info. that can help optimize cam event timing relative to rod/piston movement.

yes this is good. have look at this stuff. stall knows his stuff and is grinding cams knowing this will help on cam grinds . there is very costly desktop dyno programs that work with a cam doctor and will show the pistons dwell time and pumping speed much more i think it is $4000+ and you need a cam doctor to love to have one but you would need a flow bench to more money more money and dyno .

Originally posted by pat mccarthy
yes this is good. have look at this stuff. stall knows his stuff and is grinding cams knowing this will help on cam grinds . there is very costly desktop dyno programs that work with a cam doctor and will show the pistons dwell time and pumping speed much more i think it is $4000+ and you need a cam doctor to love to have one but you would need a flow bench to more money more money and dyno .

That's why it's good that the cam manufacturer's do all they're testing. This is where quality cams surpass cheap cams. A company that puts a lot of effort into test and development is on top of the list.

yes i go over evey thing i can think of and some out of the box stuff. and hit the cam grinders with it. if they sound like they do not know that i am trying to do. i will talk to some one that does sometimes shelf cam will not work . some of the cam grinders will try to fit a round peg in a square hole

Originally posted by pat mccarthy
yes i go over evey thing i can think of and some out of the box stuff. and hit the cam grinders with it. if they sound like they do not know that i am trying to do. i will talk to some one that does sometimes shelf cam will not work . some of the cam grinders will try to fit a round peg in a square hole

About 15 yrs. ago I called a major cam maker from TN. about building a few custom ground roller cams for a BBC with about a 300 shot of N20.Their responce was 'THE ENGINE DOES NOT KNOW IF IT IS ON N20'.Now I see they have their own n20 cam grinds.Over the years some cam companies have worked with me some have not.I think an independent engine builder who lives in the dyno room is your best bet for this type of info.

Yup, me too Erik. Gonna go talk to my dyno guy about this stuff next week. Sure glad I'm learning all this BEFORE I start ordering parts.!!!!!!!

Hey camero,leave room for the rest of the world! Until God dies and gives you the job why don't you consider this, the rest of the world may be different. And until you beat everyone at everything why don't you quit playing mr. "know it all" and don't try to instruct everyone on hotrods! I've been driving a 377 on the street just fine for 9 yr's. now and you have said on here that it can't be done,well guess what, there are combo's that you have not tried! Got news for ya,,,don't mean to hurt your pride or be rude but you will 'never' know it all or be able to tell 'all'. Live and let live,,,,it won't mean your a loser if others can know more than you or out-do you,,,there will always be somebody better,that's life. Do you have to be-little and put down people in order to feel ok with self? Do you realize how you come across on here sometimes? Or,,,do you even care boss?