AMC poops out at Jeg's PHR Engine Masters Challenge

[Holeshot]

Here's 617 HP with 11~1 (10~1 is max for shootout), ported Indy SR-1s, & Hedman stepped race headers. It's bored to 4.195", which can use Chevy 400 smallblock O.S. pistons & H-beam rods.



Same engine with 10~1 peaks @ 593 HP & 510 ft/lbs tq., adding an 1150 Dominator adds 11 HP & 6 ft/lbs.

Bumping the stroke back up to 3.68" yields 586 HP & + 20~40 ft/lbs of torque below 6500.

(according to Dyno2000)

[Blown7]

BTW Jeff what was the thickness on the top ring land you went with? I am looking at a blower motor build shortly here and I am thinking a .3125 top ring land.

I have to old "CRS" syndrome I'll look it up in my notes today.
I remember that JE Pistons engineering department had to really work at it, given the dish depth and what was left to get a ring groove in there without sacrificing strength.

Jeff

Ok the piston part number is 24490
piston type Dish-flat bottom
bore 4.187"
dish depth .318"
comp distance 1.495"
intake .260"
exhaust .255"
all at 18 degrees
Valve pocket depth measured from deck

Groove Land
top .064" .300"
2nd .064" .180
oil .188 .100"


Pin diameter .990 ( I went with a BBC pin)
Pin length 2.930 with double spirol locks (full floating pin)
Weeight 539 grams

Just for giggles for (1980CJ7) the clearance as specified by JP is .0055 clearance for bore size. Yes these are forged pistons but I allowed .0085" for the use of Nitrous.

Jeff

[jeepsr4ever]

I figured that top groove land would be at least .3

[Blown7]

I figured that top groove land would be at least .3

It is, the board program seems to not let the poster separate two columns. The first is supposed to be the ring width and the second is the distance from the grooves, the "Z" dimension.

Jeff

[82Waggy]

I guess my philosophy is this: I would rather have 350 hp at 2500 rpm..than 500 horse at 7000..

I'm with you Goose!

More specifically, I'd rather have 400ftlbs at 1800rpm than 500ftlbs at 4500rpm.

[Holeshot]

Not everyone is in competition to see how slow they can go!!!

Why must you assume that EVERYONE wants to go put-a-put-a-put everywhere they go?

I'd bet that there are more ppl here that want to go fast.

If they want to go slow they should get one of those off-brand units from Chevy, Ford, the Japansies, or the Chinese.

Taking an engine with such great potential & choking it down is like pulling a couple of plug wires off of your Viper.

[82Waggy]

I actually like to do both, reference my signature.

Point is, what is the application for the engine in question.

Holeshot always seems to be promoting high rpm power. Nothing wrong with that, but maybe not always the best advice for street or off road applications.

[Goose]

Holeshot.. you simply misunderstand.. there is such a thing as a purpose built engine.. and when people post asking for a moderate street / trail engine.. that is what they want, not a sales pitch for a dominator equipped 7500 rpm race motor (becuase it would be blasphemy to not build each and every engine to it's maximum potential) If you will notice.. so when I can afford a viper.. I wont pull the plug wires off of it.. cause I like to go fast too.. (by the way maybe you missed the post way back when I put up pictures of my 1938 Dodge street rod with the small block Ford in it..) trust me it is not built to go slow..but the fact that it's purpose is not a daily driver nor is it built for bottom end. So relax don't take this so personally.. you want every motor you build to be a high rpm big horse unit.. thats fine your money your engine.

In this instance I am simply saying those guys did a pretty good job of making decent power out of an AMC with normal parts. it wasn't that bad a showing..

[jeep_man_401]

I'm not to sure that dyno 2000 is all that accurate. I've see alot of posts using that as more than a guide. I believe that the dyno 2000 can point trends in power, but as far as graphing hp and tq curves I think it can be way off.

I will post my specs for my engine, that was on a dyno, for anyone that thinks they have a accurate dyno sim and we'll see how far off they are. I even have flow numbers for the heads to boot!

[Goose]

Hey Jeep man.. I have been meaning to ask how did that build turn out? do you have enough bottom end to do what you want? and did the dual carb setup work out??(I saw the pics.. it looks pretty cool stick up there)