Jeep Strokers

Hi, everybody!

I've been reading this crasy forum since I've bought my '99 Jeep Grand Cherokee WJ and dreamed to build a stroker. My Jeep has 4" custom long arm lift and starves for more power and torque for comfortable highway driving.
Since here in Russia we have financial crysis and our local currency has fallen down, all spare parts are twice expensive now.

Unfortunately two weeks ago my 4.0L 300tkm engine has spat out fifth piston and caused crack in cylinder block. That's why I decided that it's time to build a stroker.
I've already bought 4.2 machined crankshaft with main bearings ($150 + $150 shipping). I have spare WJ block ($50) and set of 4.0 conrods ($20). I'm gonna shorten conrods to make them fit ($80) and thus I will have zero deck clearance and no need to shave the cylinder block. My 0331 head is fine, no cracks. I've only replaced oil caps and will renew plain surfaces and do porting. I also have one 0630 head but it has one broken eye of exhaust manifold.

I drive LPG so I assume my CR will be between 9.5 and 10.

Now I am ready to buy pistons. So should I choose cast or hypereutectic?
http://www.ebay.com/itm/171251622772?_t ... EBIDX%3AIT
http://www.ebay.com/itm/171704391049?_t ... EBIDX%3AIT

I will order pistons +0.20 and moly rings. My friend says that rings are working, not pistons.

darkcorp wrote:I'm gonna shorten conrods to make them fit

Please tell me you're not serious about doing that!
Your only two viable options are to either buy a set of 4.2L conrods to use with those ebay pistons, or use the 4.0L conrods as they are with a set of custom pistons (Russ Pottenger can supply).
I can understand you wanting to save money but shortening the conrods would be a path to an expensive disaster.

Don't worry about the shortening of conrods. That was common practice before we were young.

Rather than shortening a cast 4.0 connecting rod which I'm assuming is going to involve welding, why not a cast piston with a 4.2/258 rod?

Also there's a consideration if you have the ability to deck your block Is my CNC dished 2229 piston with the short 258 rod.

You're welcome to email me and I could forward you some pricing and pictures of the finished product.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Cell (626) 673-2203
Email/PayPal: [email protected]

No welding involved in shortening of conrods.





If I mill the deck to get good quench do I need short pushrods?

The examples you're using is with a steel rod.
You've had the same success with cast rods?

I know you're in Russia with a bad economy and exchange rate but still seems Kinda scary when you could avoid this with a $30.00 to $40.00 set of 258 rods.

Whenever your machining a significant amount off a cylinder head or a deck of a block there's a good chance you'll need a shorter pushrod.

Let me know if I or others can help in anyway,

Russ

darkcorp wrote:Don't worry about the shortening of conrods. That was common practice before we were young.

Back then they could get away with it 'cause engines were pretty crude and operated at much lower rpm.
You only need one shortened conrod to break and it's goodbye engine so why take the risk for the sake of saving maybe $200 maximum?

Hi!
I've got a set of 6 Enginetech 677AP pistons and moly rings now.
I've also measured piston dish and it's 13cc only (that's not as I expected). So my calculations gives me CR 10.5 (DCR 8.7) with OEM'99 cam, zero deck high and 0.043" gasket. I guess that's too high even for LPG.

There are a few ways to solve the problem.
1. I can dish pistons to 18cc and it will reduce CR to 9.96 (DCR 8.6). But I didn't found yet who can make this in my town.
2. I can take metal from head and enlarge combustion chamber from 58cc to 63cc (CR 9.96, DCR 8.6).
3. I can use RENIX (87-90) or HO (91-95), that will keep my CR 10.5 but drop DCR by 0.7-1.4 units.

What do you think?

I think you should have listened and returned 677AP`s and ordered pistons from Russ or other supplier with a larger dish volume.

jsawduste wrote:I think you should have listened and returned 677AP`s and ordered pistons from Russ or other supplier with a larger dish volume.

I have a CNC program that allows me to increase the existing dish to any desired volume you need.

My custom cast pistons that I sell for $200.00 are a low-cost alternative to my $495.00 custom forged pistons

Russ

darkcorp wrote:I've also measured piston dish and it's 13cc only (that's not as I expected).

Not what I expected either!

So my calculations gives me CR 10.5 (DCR 8.7) with OEM'99 cam, zero deck high and 0.043" gasket. I guess that's too high even for LPG.
What do you think?

If you run the engine only on LPG that'll probably be fine. With LPG you can run at least one full point more compression than with regular gasoline.

счастливого Рождества.

Wow, Dr.Dyno! I know that you speak 7 languages, but I couldn't imagine Russian is one of them. Thank you! I speak only Russian, Tatar, English, German and Turkish only.

Usually I run LPG but you know when you go to an expedition sometimes it hard to find good fuel neither lpg. So is it OK with CR 10.5 DCR 9.1 to use EU95 (US91) octane or I should always have a bottle of octane corrector?

Cheromaniac wrote:

darkcorp wrote:
So my calculations gives me CR 10.5 (DCR 8.7) with OEM'99 cam, zero deck high and 0.043" gasket.

If you run the engine only on LPG that'll probably be fine. With LPG you can run at least one full point more compression than with regular gasoline.

I have mistaken, calculation gives me CR 10.5 DCR 9.06!
I guess DCR 8.7 will be only if I drop CR to 10:1.

And I'll just mention that an average bottle of "octane corrector" only bumps it .3 octane points when it says 3 points, so it really doesn't do much. There is also a point of diminishing returns adding more than one bottle. It's basically useless. The is no good substitute for refining the fuel better to begin with.