Jeep Strokers

I found a already assembled stroker...
4.0 block
258 crank
258 rods
Speed Pro H825CP pistons 15.8 dish
standard height deck
ported head 1.91/1.5 valves yada yada yada...

I did the math on the stroker calc and came up with over 10:1 compression... that seems a little high for a daily driver...
what do you think?
also-- my plan was in the future to add a little spray to the mix... will these pistons deal with the Nitrous in low doses?
Like a 75 shot?

What cam is in it?
You should be fine with nitrous in small doses, it's when you get the little voice in yer head that says "oh come on a little more wont hurt anything" that makes things iffy

I don't know the cam.. I called the guy and he didn't know-- he supposed to call me back with all the specs... I will post when I get them.

It will be going in a 97 so OBDII...

It's the deck height and high compression that worries me... ping ping ping BOOM! If I had the deck down a bit, it might be ok...

I wont pretend to be a cam master in anyway ,but from what I understand ,the dcr is more important when figuring what fuel you can run. and you need the cam specs to figure that out. personally i dont think 10:1 scr is terribly high,(my girl friend had a kia with 10:1 stock) but these 6's of ours seem a little touchy.

tragiccomic1972 wrote:I found a already assembled stroker...
4.0 block
258 crank
258 rods
Speed Pro H825CP pistons 15.8 dish
standard height deck
ported head 1.91/1.5 valves yada yada yada...

I did the math on the stroker calc and came up with over 10:1 compression... that seems a little high for a daily driver...
what do you think?
also-- my plan was in the future to add a little spray to the mix... will these pistons deal with the Nitrous in low doses?
Like a 75 shot?

If that engine's the same as the 4.6L low buck stroker recipe from My Stroker Recipe Page, the static CR will be 9.6:1 and it'll need to run on minimum 91 octane.
If you're going to use N2O, I suggest you don't go higher than a 50 shot unless you can boost the output of the stock fuel pump.

Dino-- the man, the myth, the legend... it is my honor!

The guy says it was built with your low buck rock crawler guidlines, but with the speed pro pistons.... I thought that those pistons, with that little dish, would push the compression up to high...

tragiccomic1972 wrote:Dino-- the man, the myth, the legend... it is my honor!

The guy says it was built with your low buck rock crawler guidlines, but with the speed pro pistons.... I thought that those pistons, with that little dish, would push the compression up to high...

I did the 4.7 L from Dinos web page and rum N2O with several nozzles. 25-50 HP no problem and the 75HP runn sligtly lean in high RPM but not realy scary lean. For safety I stay with the 50HP. If you have the chance, go for the Venom 100 computer controlled kit, also shown at dinos page. Safest way to rum N2O on an jeep, in my opinion!!

Don't forget to design the engine from the beginning for the nos. extra wall to piston clearnce, spark plugs etc...

Hey Tobias, glad to see you're still around. How's the Frankenstroker going? I bet you're still grinning from ear to ear since you had it built. I've been doing the same for almost 7 years!

Thanks for the advise.. can you tell what the piston to wall clearance should be for a 4.7 set up to run N02 should be? What kind of plugs are you running???

Cheromaniac wrote:Hey Tobias, glad to see you're still around. How's the Frankenstroker going? I bet you're still grinning from ear to ear since you had it built. I've been doing the same for almost 7 years!

Yes, I am still smilieng when I drive Frankenstein. So much fun and many modern SUV driver are surpriced when they try to overtake my old rusty bucket, but they can not....

tragiccomic1972 wrote:Thanks for the advise.. can you tell what the piston to wall clearance should be for a 4.7 set up to run N02 should be? What kind of plugs are you running???

The Pistons have an clear discription on the packing and on the homepage. Depence on what you doing to run, Nitrous & Meth, only nitrous, Turbo & Nitrous. I use it only few secounds and with max 75HP shot, so I went for additional 0.005" . If you go with much more you will have to change the oil very often.
Also I used 1 step colder spark plugs with "non extended tip"