Gearing Question for stroker folks

[tetsulo]

I've searched and haven't come up with an answer that is satisfactory to me, so I'm going to ask a gearing question. Here is what I can tell you...

I have a 1990 Jeep Comanche with an AW4 with 120k miles and a blown headgasket.

I have a Dana 30 and a 35 with 3.55's as best as I can tell
I'm running 31x10.5 AT's with 5" of lift.

I have a Golen Stroker kit on order. Should be ready for pickup in a few weeks.

With the stroker I am having these items installed.

24lbs fuel injectors
map adjuster
hesco adjustable fuel pressure regulator
hesco high flow water pump
borla header
rusty's xj air tube + K&N Filter
artsound 59.5mm throttle body (wonder if I'll ever get my money back from xj-armor )
random technology high flow cat
High flow thermostat housing
180degree thermostat
3 core radiator
Probably a 2.25 exhaust with a flowmaster of some kind (this has not been decided and I'm looking for recommendations on this as well)

The truck is primarily a DD with fairly long east coast highway runs involved. long windy hills etc. I would estimate I travel 600 to 700 mile a month for job related stuff.

From what I have read consensus says that 4.10's are the way to go with 31's. I dig that.

My question is -- do I HAVE to do the change right away? I didn't budget for the cost (of a gearing change), but I don't want to fry the transmission or cook the engine or anything silly.

Should I just stop using overdrive and leave it in third until I get the gears swapped?

thanks in advance

tetsulo

 

[Ramsey]

even with a stock motor you will be fine with 3.55s and 31s although it is not ideal it is safe.

 

[Eagle]

I found from personal experience in my MJ that 31s and 3.73 gears is exactly the same overall drive ratio as stock tires with 3.54s. So by going to 31" tires you are dropping your RPMs by approximately 10%, which will put your engine speed at 65 MPH right around 2000 RPM. That's still better than a stock 5-speed with 3.07 gears. Not to worry.

 

[old_man]

The lower torque curve of the stroker will make it a lot easier to run taller gears. It will put you more in your torque band on the highway. You should be fine. Actually with a stroker, if you gear it too much and get the rpm's up too much, you can actually hurt your mileage.

 

[tetsulo]

I feel a lot better that I haven't totally whiffed on gearing. I'll wait till after the engine is broken in and I have some miles under my belt before worrying about it. Why is it that so many people (myself included) find this site after a project has been started . I'm willing to bet in the last few days I have read 200 pages worth of posts on this site.

I think I'm going to swap the harmonic balancer while the engine is out. I don't know the condition of the one that is in there currently. Is the only option a stock replacement?

Any insight on exhaust pipe diameter?

Thanks again for the insight.

Matt

 

[corbinafly]

I think I'm going to swap the harmonic balancer while the engine is out. I don't know the condition of the one that is in there currently. Is the only option a stock replacement?

Any insight on exhaust pipe diameter?

Thanks again for the insight.

Matt

From what I've read, the stock balancer is our only option. I'm my be wrong. I'm sure someone will correct me if I am.

I'm running a Borla header into a Carsound high flow cat and 2 1/2" all the way back with Magnaflow muff. It sounds great and I think it's about perfect for my 4.6 stroker. I used to have a Flowmaster 40 series, but changed it due to an annoyingly loud resonance at cruising speeds. And it sounded a little "tinny"/harsh for my tastes.

K

 

[virginxj]

, but I don't want to fry the transmission or cook the engine or anything silly.

Should I just stop using overdrive and leave it in third until I get the gears swapped?



tetsulo

if your rpms fall to where the converter is slipping you should consider installing the converter lock up switch, and while your at it do the 1st gear lock out switch, you'll love them both.

 

[Eagle]

I think I'm going to swap the harmonic balancer while the engine is out. I don't know the condition of the one that is in there currently. Is the only option a stock replacement?

Crown. Decent quality, half to two-thirds dealer price.

Any insight on exhaust pipe diameter?

Stay with stock 2-1/4 inch. 2-1/2" is for higher RPM work -- you gain top end horsepower and lose low-end torque.

 

[Goatman]

I have a 4.6L stroker, and you will have plenty of power to run the 31's with the stock 3.55 gears. In fact, if you're always going to run 31's I'd never regear it. One other comment, though, is the strength of the D35. I have a friend with a ZJ who blew his D35 within a month of installing a stroker, and he hadn't even wheeled it yet. Of course, your MJ is a little lighter in the rear.

I'm real happy with my 2.5" exhaust. I don't think low end torque is an issue since these motors have so much of it. Mine has plenty, and it really sings as the revs come up.

You have some parts in your list that you could do without, or at least run it before you spend the money to see how it does. The 24lb injectors should work fine at the stock fuel pressure, so you could wait on the adjustable regulator. It's also questionable that you need the adjustable MAP sensor. I don't use either of them on mine.

BTW, you're truck is going to become MUCH more fun to drive.

 

[Dr. Dyno]

You have some parts in your list that you could do without, or at least run it before you spend the money to see how it does. The 24lb injectors should work fine at the stock fuel pressure, so you could wait on the adjustable regulator. It's also questionable that you need the adjustable MAP sensor. I don't use either of them on mine.

Agree. You don't need the adjustable fuel pressure regulator. I have a HO-based stroker and I'm running Ford 24lb injectors with a homebrew MAP adjuster set at 5.15v (stock is 5.04v so that's a 2% enrichment) and stock regulator. My A/F ratios, gas mileage, and emissions are excellent.
You may not need a MAP adjuster at all on your Renix stroker.

As far as gearing in a 5-speed XJ goes, mine is exactly where it should be now that I have the stroker. I have a D30 front, D35 rear, stock 3.07 axle gears, and 27.4" tires. The D35 has survived 11500 miles of stroker torque so far without any problem. I think it's the addition of bigger tires as well as more torque that kills the D35.
_______________________________
Dino's "Mean Green Machine"
1992 XJ Laredo 4-dr - 4.6L HO Stroker - 186k miles - AX15, NP231, D35c, D30

265hp@4900/325lbft@3500, 1/4 mile = [email protected], 0-60 = 5.7secs
Websites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks

 

[tetsulo]

Thanks again for all the info.

I already have the map adjuster and fuel pressure regulator here. As this was a spendy project I wanted to get all my costs into a spreadsheet and try and avoid any surprise expenses after it was done.

Considering that I am certain that I have been stiffed by XJ-Armor (no product and no contact from them at all in almost three weeks) and the fact that the Borla Header was slightly over my estimated cost I'm running about 2% over budget right now.

Chad from Golen Engine Service was up front about the map adjuster and FPR. He said that some people need them and other's don't. I can't decide now if I should wait on having the map and fpr installed. If I don't need them I could post them for sale here or on ebay or something.

I have some concerns about the 35 holding up. In the north east here jeeps are plentiful and I don't think I'll have much of a problem finding a 44 if need be

The exhaust resonation at cruise that folks are talking about is something I desperately want to avoid. My other car is a NA Mitsubishi 3000GT. It's stock exhaust characteristics is ideal in my book. Quiet at idle, deep and throaty when stepping into the throttle, and quiet at cruise.

I think I'm leaning towards 2.25" pipe and a flowmaster 50.

What the the heck is the URL for that website which has recorded sounds of different vehicles with different exhausts? I stumbled across it the other day and haven't been able to find it again.

Thank you everyone for the great responses

Matthew

 

[tetsulo]

if your rpms fall to where the converter is slipping you should consider installing the converter lock up switch, and while your at it do the 1st gear lock out switch, you'll love them both.

Think I found it -- is that this?

http://awshifting.com/4-0.htm

tetsulo

 

[CRASH]

Ditto on the MAP and FPR. Not necessary on a Renix. Your computer has more than enough mapping to handle a 4.6 with 24# injectors.

A note, I can cruise my stroker at 3100 RPM all day long, and do it regularly. I get about 16mpg running this way, fully loaded (5,000+ pounds), with 4.88's and 35" tires.

I ran 3200 RPMs all the way from NorCal to Arizona and back through the desert. The only time I dropped below this RPM was to stop for fuel.....moral: well-balanced strokers have a wide rev range. Mine is biased towards the high side a bit, but still has plenty more on the bottom than a 4.0.

I have a 4.6L stroker, and you will have plenty of power to run the 31's with the stock 3.55 gears. In fact, if you're always going to run 31's I'd never regear it. One other comment, though, is the strength of the D35. I have a friend with a ZJ who blew his D35 within a month of installing a stroker, and he hadn't even wheeled it yet. Of course, your MJ is a little lighter in the rear.

I'm real happy with my 2.5" exhaust. I don't think low end torque is an issue since these motors have so much of it. Mine has plenty, and it really sings as the revs come up.

You have some parts in your list that you could do without, or at least run it before you spend the money to see how it does. The 24lb injectors should work fine at the stock fuel pressure, so you could wait on the adjustable regulator. It's also questionable that you need the adjustable MAP sensor. I don't use either of them on mine.

BTW, you're truck is going to become MUCH more fun to drive.

 

[rsalemi]

For exhaust I recommend the Dynomax 2 1/2 with Super Turbo muffler. I have had 3 of those cat-back systems (on 4.0 and 4.7 stroker) over the years and they are relatively quiet at cruise and a bit noiser under acceleration. I've never seen somebody posting that their Dynomax was too loud - but often see people removing flowmasters for that reason. Dynomax cat-back at Summit Racing around $100

 

[CRASH]

For exhaust I recommend the Dynomax 2 1/2 with Super Turbo muffler. I have had 3 of those cat-back systems (on 4.0 and 4.7 stroker) over the years and they are relatively quiet at cruise and a bit noiser under acceleration. I've never seen somebody posting that their Dynomax was too loud - but often see people removing flowmasters for that reason. Dynomax cat-back at Summit Racing around $100

I love dynomax and was bummed that my old D-max muffler wouldn't fit with the new suspension. I went to the $14 Summit Turbo muffler. Even quieter than the D-max, and it flows very well. I run 2.5 mandrel bent from the head pipe to the tail pipe. Really helps the motor rev.

 

[tetsulo]

I found a local custom exhaust guy in town. I went and talked to him. He suggested 2.5 inch tube with a magnaflow glass pack of some kind. He said that it wouldn't have the tinniness that the flowmasters do. I've always thought that glasspacks are LOUD. But these are fairly large oval style unlike the cherry bomb type swollen tube that I typically think of as a glass pack.

$14 dollar turbo muffler? Do you have a link? I am fairly certain that XJ cat backs aren't the same as an MJ. I'll probably have the guy bend me up the tube for the cat back. He gave me a verbal estimate of about 3 bills including the magnaflow (and stainless tube) which seemed pretty reasonable to me.

I really appreciate you all chiming in.

Matt

I think I found the muffler on summit...

is it this part number? SUM-630125

 

[CRASH]

630222 or 630225

Depends on where you want your inlet/outlet.

I found a local custom exhaust guy in town. I went and talked to him. He suggested 2.5 inch tube with a magnaflow glass pack of some kind. He said that it wouldn't have the tinniness that the flowmasters do. I've always thought that glasspacks are LOUD. But these are fairly large oval style unlike the cherry bomb type swollen tube that I typically think of as a glass pack.

$14 dollar turbo muffler? Do you have a link? I am fairly certain that XJ cat backs aren't the same as an MJ. I'll probably have the guy bend me up the tube for the cat back. He gave me a verbal estimate of about 3 bills including the magnaflow (and stainless tube) which seemed pretty reasonable to me.

I really appreciate you all chiming in.

Matt

I think I found the muffler on summit...

is it this part number? SUM-630125