Stroker Perfomance (squeezing out a couple more horses)

[VAhasnoWAVES]

99' XJ: 4.6L, manual, 231, 8.25 rear.

ive been driving my stroker for a number of months now and have put quite a few miles on it. between the PO and i there is somewhere around 35k on the motor. it runs PHENOMINAL, a big difference in torgue and power from the 4.0s ive had in the past. i know shes got some more power but the engine just needs to BREATH. and with a recent inspection revealing an exhaust leak to me, i think its time to get to work... i just want some oppinions from those with knowledge on strokers:

-what recomendations on exhaust systems can you make? ive been thinking 2.5" all the way but am unsure about the use of the stock manifold or having a header made/ordered. muffler and cat recomendations? (the stock exhaust is in place at the moment)
-the throttle body was milled (i forget to exactly what size, i will double check asap) but it does whisle a bit and im looking at replacing it. would upgrading the throttle body and air intake be worthwhile? my xj never sees dust or mud, stricktly a beach fishing/DD rig.

im sure i have more questions that are eluding me right now... :banghead:

 

[Talyn]

http://www.strokedjeep.com/ makes a larger throttle body that doesn't whistle.
Magnaflow makes a nice exhaust kit and I've heard good things about dynomax, but I think that dynomax is more of a stock replacement.

What injectors are you running, BTW?

 

[VAhasnoWAVES]

a set from ford off of an 03' cobra.

 

[bigdaddyjlove]

LT-1 injectors from a 96 Impala SS

 

[16guns]

Did you install the stroker yourself?

 

[Talyn]

You should be pretty good on the injectors, but I'd bet you are running a bit rich after 3000 RPM in WOT

 

[gradon]

After switching to an ss magnaflow 2.5" muffler and ss mandrel tailpipe from the 2.25"in/2"out Borla catback a week or so ago, I'd say that a complete 2.5" exhaust from header collector to the back would be good for a stroker(bigger if you're gonna add a turbo or blower). I definitely gained more power all the way around, so I guess the Borla was choking it out a bit.

 

[VAhasnoWAVES]

Did you install the stroker yourself?

the PO did actually. he used it as an SUV hauling motors around and such. now its my DD. ive been over it with a fine toothed comb just short of opening up the block and double checking the measurements. i was given a complete parts list as well including costs. the PO has everything fairly well documented and it runs great for me so im happy, just ironing out the wrinkles.

You should be pretty good on the injectors, but I'd bet you are running a bit rich after 3000 RPM in WOT

the PO and i both have this thought as well. and i keep getting a code for a cylinder 6 misfire once in a while. i beleive the lop in the cam and the firing order are a bit off. ive looked at a couple different systems id like to flash the ECU with but am unsure if it can even be done. even if it cant be flashed how should i go about getting the right fuel/air mixture?

this is one of those questions i forgot to ask in the original post. lol.







the TB was milled strait through to 60mm and like i said does whistle a bit. thanks for the link Talyn.

 

[Talyn]

You can have it flashed by [email protected]. He has a bunch of things that they can do. For the AFR you need to get a wide band O2 sensor system to see what your AFR is first. One with logging works well. Then correct the AFR with a piggy back like a PSC1, FTC1, Apexi, Omnichip or something similar. If you have a dyno near by you can do a dyno pull and get a decent idea of whee your AFR is. It will be after the cat, but it will give you an idea. Another option is talking to someone like Hesco and see if they can sell you a Omnichip with a program some what tuned to your setup. There is also someone on here that sells the OmniChip, IIRC.

 

[urban yan]

You can have it flashed by [email protected]. He has a bunch of things that they can do. For the AFR you need to get a wide band O2 sensor system to see what your AFR is first. One with logging works well. Then correct the AFR with a piggy back like a PSC1, FTC1, Apexi, Omnichip or something similar. If you have a dyno near by you can do a dyno pull and get a decent idea of whee your AFR is. It will be after the cat, but it will give you an idea. Another option is talking to someone like Hesco and see if they can sell you a Omnichip with a program some what tuned to your setup. There is also someone on here that sells the OmniChip, IIRC.

That was one expensive statement lol

 

[jeepinwi]

Howdy stranger-

For an FYI to everyone, I built the engine and installed it myself. I am the previous owner. I know just as well as VAhasnowaves that the engine has more power in it. For this stroker, I believe a 62-63mm TB would be perfect and a 2.5" exhaust from the manifold back would be optimal. the 2.5" exhaust would allow greater flow at high RPM's, but keep enough backpressure to maintain good torque. For a little extra power, an APN header would be a fine addition. The 2.5" converter I sent with the Jeep should work perfect with the exhaust. You'll just have to get an oxygen sensor bung welded in. If money weren't an obect, I would have gone with a magnaflow muffler. That Thrush muffler will work fine, but may not have the sould you're looking for. It was cheap, that's why I bought it.

Injectors are rated at 25 lb/hr, so they should be sufficient with the engine breathing better.

I ported the cylinder head myself, so I know that it can support greater airflow. The port job was not extreme...I simply smoothed things out and opened up the ports a bit.

Walt-
The extra air filter and crude heat shield I sent with the Jeep worked very well...at least I thought so. To improve it, I would replace the rubber elbow attached to the TB with something smooth, and I would wrap the intake tube with an exhaust wrap. The cone filter has seen about 25k miles of use, so it may need a cleaning or replacing.

Another cheap mod would be to strap a heat shield on the bottom side of the intake manifold. http://www.angelfire.com/my/fan/manifold.html

Finally, if you go about doing these mods to make the engine breath better, you may want to look into stronger valve springs. The stock valve springs are good up to about 4800 rpm's. At that point the engine seemed to run out of breath(couldn't move enough air at higher rpm's).

 

[VAhasnoWAVES]

Howdy stranger-

For an FYI to everyone, I built the engine and installed it myself. I am the previous owner. I know just as well as VAhasnowaves that the engine has more power in it. For this stroker, I believe a 62-63mm TB would be perfect and a 2.5" exhaust from the manifold back would be optimal. the 2.5" exhaust would allow greater flow at high RPM's, but keep enough backpressure to maintain good torque. For a little extra power, an APN header would be a fine addition. The 2.5" converter I sent with the Jeep should work perfect with the exhaust. You'll just have to get an oxygen sensor bung welded in. If money weren't an obect, I would have gone with a magnaflow muffler. That Thrush muffler will work fine, but may not have the sould you're looking for. It was cheap, that's why I bought it.

Injectors are rated at 25 lb/hr, so they should be sufficient with the engine breathing better.

I ported the cylinder head myself, so I know that it can support greater airflow. The port job was not extreme...I simply smoothed things out and opened up the ports a bit.

Walt-
The extra air filter and crude heat shield I sent with the Jeep worked very well...at least I thought so. To improve it, I would replace the rubber elbow attached to the TB with something smooth, and I would wrap the intake tube with an exhaust wrap. The cone filter has seen about 25k miles of use, so it may need a cleaning or replacing.

Another cheap mod would be to strap a heat shield on the bottom side of the intake manifold. http://www.angelfire.com/my/fan/manifold.html

Finally, if you go about doing these mods to make the engine breath better, you may want to look into stronger valve springs. The stock valve springs are good up to about 4800 rpm's. At that point the engine seemed to run out of breath(couldn't move enough air at higher rpm's).

:lecture: thanks for chiming in Brian.

i believe the system he and i talked about was the Apexi SAFCII, and he did mention Kolak as well. i actually found a very reputable shop in my area that specializes in computer tuning, dyno and all. so ill definantly be talking to them soon. ill deffinantly get numbers for us to work with. ironically its right accross the street from the surf shop, go figure.

 

[Dr. Dyno]

In my experience, a 62mm TB and a 2.5" exhaust from header to tailpipe is sufficient on a mild 4.6 stroker putting out up to 250hp at the crank. The modified Mustang 65mm TB that I'm using is overkill. With the stock cam and stock valve springs, my stroker pulls to the 5200rpm rev limiter without valve float issues.
_____________________________________

1992 XJ Laredo - manual - 4.6 Stroker
[email protected] - 202rwhp/258rwtq - 3620lb w/ driver

1995 Mustang GT - automatic - 5.0 V8
[email protected] - 244rwhp/284rwtq - 3480lb w/ driver

 

[jeepinwi]

In my experience, a 62mm TB and a 2.5" exhaust from header to tailpipe is sufficient on a mild 4.6 stroker putting out up to 250hp at the crank. The modified Mustang 65mm TB that I'm using is overkill. With the stock cam and stock valve springs, my stroker pulls to the 5200rpm rev limiter without valve float issues.

Dino-
VA's stroker has a Crane 753905 cam with the higher lift. When I was building the engine, a lot of the camshaft failures were surfacing(including yours), so I decided to use the Crane cam, but go with stock valve springs. I believed there were 2 things contributing to the cam failures...excessive spring pressure and wrong oil. At around 20k miles on the engine, I measured the camshaft lobes' lift, and all were within .002" of specs. I know first hand the engine only wants to rev to 4800 rpm's where it runs out of breath. This may be a result of the constrictive intake and exhaust...I don't know for sure. I do know that the 60mm TB and the stock crimped exhaust down pipe are limiting what the engine is capable of.