I need to know the volume of a 4.0 head

Hi I am building my second stroker motor, but unlike the last time where I went for economy and reliability. This time I am going for all out top-of-the-line performance. So...In doing so I am having custom forged pistons made and I need to know the specs (most importantly the volume) on both the pre 91 and post 91 4.0 cylinder head. Thanks for any help!!!

gzweber said:

Hi I am building my second stroker motor, but unlike the last time where I went for economy and reliability. This time I am going for all out top-of-the-line performance. So...In doing so I am having custom forged pistons made and I need to know the specs (most importantly the volume) on both the pre 91 and post 91 4.0 cylinder head. Thanks for any help!!!

Click to expand...

244.040 Cubic inces
Billy

EDIT: oh, you just wanted the head. N/M

My understanding from the strokers group on Yahoo is that there is great variance between heads, even in same year models due to casting flash, previous milling, etc.
I know there's a write up somewhere re: doing the measuring yourself, of course, this is only viable if you have the head off the block...
check the strokers group on Yahoo, you should be able to get some info over there

The factory manuals claim all the chambers have the same volume, but as reported casting and machining differences reflect differences (even from chamber to chamber on the same head).

If you are going to blueprint the total assembly, polish and match the port volumes on the head of your choice (the preferred 91-95 head). The cc volume will not be a guess and you will eliminate the guesswork.

Greg (on strokers) had a set of forged pistons from JE made that were very nice concerning the chamber relief and resulting compression ratio. The only improvement would possibly be to slightly angle the floor of the relief to direct the exhaust flow to the respective valve, and minimize the dilution of the intake charge by helping the charge sweep the piston crown and chamber during the cam timing overlap. The peak power gains would be small, but the torque off the peak could be improved by reducing the overlap and still having the same level of chamber scavanging.

Good luck on the project.

Ok thanks, but can anyone tell me what the stock specs are? I just need a halfway decent number for the moment so I can get my pistons ordered. If possible I want to know the volume of both the high and low port heads (in other words HO non-HO). I am trying to keep my compression under 9.5:1 or at least no higher anyway. So basically I just need the volume of the head so we can figure out exactly how my pistons are to be set up.
Thanks

gzweber said:

Hi I am building my second stroker motor, but unlike the last time where I went for economy and reliability. This time I am going for all out top-of-the-line performance. So...In doing so I am having custom forged pistons made and I need to know the specs (most importantly the volume) on both the pre 91 and post 91 4.0 cylinder head. Thanks for any help!!!

Click to expand...

The combustion chamber volume of the stock 4.0 heads (HO and non-HO) is quoted by the Mopar Engines book as being between 55.2-58.2cc. I've ported two 4.0 heads (one junkyard '95 head for my old 4.0, the other's the original '92 head that's now on my stroker) and cc'd both of them. One was 56.5cc and the other was 57.0cc so that gives you some idea.
You don't have to buy forged pistons to get a 9.5:1 CR on your stroker. If you copy mine but shave 0.010" from the block surface (nothing from the head), the CR will come to 9.42:1.
My stroker performs great but it still hasn't reached its full potential yet. I know exactly how to get there though and here's what's needed:
1. 10W-30 synthetic oil instead of 20W-50 dino oil (Mobil 1 going in next week).
2. Ishihara-Johnson crank scraper. I have one in a box ready to go in.
3. Roller rockers. If Quadratec will give me the Yella Terra YT6627A's for a discounted price (retail price is $440) if we get a group buy going, I'll buy them.
4. '99+ intake manifold. They're hard to find here and expensive (minimum $180). If I can get one cheap, I'll be very happy.

At the moment, my stroker's putting out an estimated 260-265hp. With all these extra tricks, I could get closer to 280hp or 1.0hp/ci (my stroker's displacement is 4563cc or 278.5ci).
___________________________________
1992 XJ Laredo 4-dr - 4.6L I6 HO Stroker - 177k miles - AX15, NP231, D35c, D30
Estimated 261hp/322lbft, 1/8 mile = [email protected], 0-60 = 5.9secs
Websites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks

Most of the heads are in the 57 - 58 range, I had to have my 93 HO head machined to get to 55.9 cc (NHRA minimum spec is 55.2 cc for stock class (from Chrysler provided original data). Also block deck height will depend on pistons, On my stock stroke 4.0 I had to machine .018 to get to the .006 spec deck height.

Thanks for the Help!!! PS Dr. Dyno I would be interested in going in on the group thing for the roller rockers, but I sure wouldnt pay $440 for them.