Slow Stroker

[Djmack]

Hey, Ive had a stroker for a little over a year now. When i put it it, i had my initial troubles of starting it and hoping for the best. Well it runs great and everything. Except that i feel like it has a lack of power that was "promised" with a stroker. I dont know how much more higher rate injectors will do, but im still running the stock ones. This may be it, but i also have 31" tires on 3.07 gears behind an ax15. Any thoughts? Would installing better injectors do it? (It was also build with a mild performance cam)

[Muad'Dib]

You need to check your AFR's... Running stock injectors with a Stroker is never good. Hopefully you havent done WOT runs with those. It would run super lean and have a loss of power and cause possible engine damage.


FWIW i was "underwhelmed" at first with my stroker until i realised how much of a difference the torque made. The "get there fast" or "speed" only improved slightly. You will really notice the power climbing hills or passing on the highway.

[Cheromaniac]

Hey, Ive had a stroker for a little over a year now. When i put it it, i had my initial troubles of starting it and hoping for the best. Well it runs great and everything. Except that i feel like it has a lack of power that was "promised" with a stroker. I dont know how much more higher rate injectors will do, but im still running the stock ones. This may be it, but i also have 31" tires on 3.07 gears behind an ax15. Any thoughts? Would installing better injectors do it? (It was also build with a mild performance cam)

Stock injectors are going to be too small period. What year is your Jeep and what were the stroker build specs? With that info. I can tell you which injectors to use.
Having 31" tires on 3.07 gears is definitely going to slow you down. If you don't want to downsize tires, swap in the 3.55 axle gear sets from an AW4 XJ.

[Djmack]

I've got 3.55's ready to put in, i just dont have experience with gear swapping. As far as the engine build spec's go, im not sure, i had a machine shop build the stroker for me with all the right tolerances. i think im close to 4.7.. How would i got about checking my air-fuel ratio? And, are you implying that running stock injectors could do excessive heat damage?

[SilverXJ]

Running stock injectors and hitting WOT/open loop will cause your engine to run lean and damage internal components like pistons and valves.

[Djmack]

Running stock injectors and hitting WOT/open loop will cause your engine to run lean and damage internal components like pistons and valves.

what im asking is, How? Is it due to any form of predetonation? or running hot?

[Dezertxj88]

Leaner builds more heat, thus detenation happens. Why? Because the fuel being sprayed in does cool the pistons & combustin chambers ect. Sharp points are prone to denenation ect ect..I could go on and on..
Short side is the stock 18.6lbs injectors are good for about 190 crank hp. The cheapest 4.5L low buck is making around 230hp. You need to grab some 24lbs and toss them in..grab a wideband, for around 200bucks, and get a cheap map adjuster...online for around 50 bucks.
Get your afr around mid 13's..then get on a dyno and get it tuned via the map adjuster. If you keep it as it right now its a ticking time bomb



As far as gears & tires and such go...I have a ax15, 31's and had 3.07's...I hit up a junkyard and pulled a front and rear axle out of a automatic..I got a 29spline c8.25 out of a 98 vs my old d35..much stronger and I got a D30 non-disco to replace my d30 disco. It was as easy as dropping my axle and swapping in the new 3.55 axles. The D30 came from a ABS jeep, which mean its got the stronger/bigger 760X u-joints. This option of swapping axles vs gears would be much much cheaper and easier.
To boot the 3.55's, 31's and ax15 is about 200rpm better than the stock 3.07's and 215/75's. So slightly better gearing with 31's and 3.55's:) I cruise around 1950rpm or so at 65mph on the highway.

[Djmack]

Leaner builds more heat, thus detenation happens. Why? Because the fuel being sprayed in does cool the pistons & combustin chambers ect. Sharp points are prone to denenation ect ect..I could go on and on..
Short side is the stock 18.6lbs injectors are good for about 190 crank hp. The cheapest 4.5L low buck is making around 230hp. You need to grab some 24lbs and toss them in..grab a wideband, for around 200bucks, and get a cheap map adjuster...online for around 50 bucks.
Get your afr around mid 13's..then get on a dyno and get it tuned via the map adjuster. If you keep it as it right now its a ticking time bomb

I dont know what a wideband is. And can you suggest any specific injectors for mine? I saw some where that our fuel flows at like 18psi.. So to work off that, i just need to cross multiply any injector specs i find to try and achieve a total outcome of 24#/hr at 18psi. And what ever connector that a 1995 injector harness will plug into.

As far as gears & tires and such go...I have a ax15, 31's and had 3.07's...I hit up a junkyard and pulled a front and rear axle out of a automatic..I got a 29spline c8.25 out of a 98 vs my old d35..much stronger and I got a D30 non-disco to replace my d30 disco. It was as easy as dropping my axle and swapping in the new 3.55 axles. The D30 came from a ABS jeep, which mean its got the stronger/bigger 760X u-joints. This option of swapping axles vs gears would be much much cheaper and easier.
To boot the 3.55's, 31's and ax15 is about 200rpm better than the stock 3.07's and 215/75's. So slightly better gearing with 31's and 3.55's:) I cruise around 1950rpm or so at 65mph on the highway.

Well, I already have the gears. My axles are 30/8.25. The 30, 3.55's i bought from some one for $20. the 8.25 3.55 gears are brand new and i got for free.

[SilverXJ]

Leaner builds more heat, thus detenation happens. Why? Because the fuel being sprayed in does cool the pistons & combustin chambers ect.

It is possible to run lean w/o detonation or pinging ans still result in damaged components.

what im asking is, How? Is it due to any form of predetonation? or running hot?

Detonation, pinging, or over heating components.

[Dezertxj88]

Fuel injectors are at 39psi or 43.5psi...not 18. The 18 you saw was probably 18lbs. You have Ev1 style injector clips, and you need something around 22-24lbs. Mustang cobra injectors which are blue will work.

A wideband is a air fuel ratio meter. It monitors the airfuelratio (afr). The higher the number the leaner it is, the lower the number the richer it is. On most N/A applications on pump gas your looking for a 12.5-13.5afr. Thus the reason to have it tuned! It will run alot better once its been tune. I run a AEM UEGO...cost is about 200 bucks.

[Djmack]

Uhg, i hate spending money.. but i think ill look for those ev1 blue injectors from ford.

[Winners97TJ]

X2 on the 24# Ford blue injectors. I'm running those and they work great.

Also Check your catalytic converter.

I was having "loss of power" issues up around 3k in 3rd gear and had almost NO pull. Couldn't get over 3k if I tried. Here's my post on another forum......

After wondering if I made the right decision on putting a Stroker into the Jeep vs a V8 swap, I started investigating why that pile wouldn't go up a hill in 3rd gear on the way home from a wheeling trip and why it could have progressively lost power the way that it had ever since I dropped the new motor into it.

Any guesses??? My first thought was timing/tune. (could use a lean-out on top end, but I'm hardly EVER that high in the RPM range so it can wait for now)

Wrong.

Then I thought possibly distributor/ cam position sensor goin out.

Hell, it's only $50.... Get a new one.
While I'm there, throw in a new set of plugs. The old school copper cores. Not the platinums.

Still ran like crap. Next thought........ Clogged cat???? Tell me what you think.

Here's the INLET side of the cat


Here's a picture of the great flow through this thing...... My fully charged mag light is shoved into the inlet turned ON.... View from outlet side.


And here's a chunk 'o shit that came OUT of it as I flipped the cat inlet-side-down to take the previous picture.....


I think I'm on the right track..... Thoughts?

(runs a TON better now that I threw a piece of straight pipe on it where the cat used to reside!)