Jeep Strokers

I had a few questions about this. Most people seem to baby there motors for the first few thousand miles, but what about breaking it in on a engine dyno? I'm talking from the very first crank. A local shop has a engine dyno and offers it for a full day at 600 bucks. I really want to do this! I'm thinking I could break it in and find out what it'll make all in 1 shot and would possibly try to see the changes throughout as well...like 99+ intake swap, or possibly header differences if anyone has 1 they wanna send for the test. Personally I run a thorley but would love to see the difference between it and a pacesetter with its long runners. I could also test advancing or retarding the cam? Different injectors and how they play. Throttle body sizing..I have a 60mm jeep, 65m mustang and 75mm from a 4.3l vortec. I have the newer and old ho intakes. I have a APN/borla, a few stock headers and my thorley with a 2.25" collector. Ill be welding up a nice 2.5" before it actually goes into the jeep though. I really want to test versus a pacesetter because the pacesetters got the longest primaries which should mean more low end grunt and power overall.


My worry is with all these motors dropping cams or lifters so much..would it be to much for the motor? Breaking it in from the first crank, to dynoing it repeatetivly hours later?

Opinions?

It sounds like a great plan, unless you run into issues getting the first fire, then you end up buying another day and bumping the next guy.

That being said, if it were available to me I would easily get $600 worth out of a dyno day.
If you are doing initial fire up and break-in. Make damn sure you have duplicates for every injection, ignition, or other "dammit" types of parts.

You shouldn't baby and engine on break in. First step is to break the cam in. Usually 20-30 minutes between 2000-3000 RPM, varying rpm. Next step is to do some medium hard pulls to help seat the rings. The ring manufacturer will have instructions for this. Change the break in oil. Then drive it varying engine rpm getting on it a bit, but don't baby it. No constant rpms, like highway use. Do that for 500 miles then change the oil again. If you want to run a synthetic oil I would wait at least 5000 miles before switching.

The dyno is a good idea for an engine break in. You can do the cam break in on it as it will put a load on the engine, and help get a better AFR. Then of course the ring seat procedure. The dyno shop should also have a fan to help cool the engine during breakin. However, I wouldn't be testing anything yet as parts are still tight and the rings haven't fully seated. One tip during cam breakin: Jumper the electric fan so it is running constantly. That will help cool the manifold as they tend to get very hot and even glow during cam break in. As for Pacesetter, it may look good, but every one I have heard that has used them said they fit like crap.

You must have an old Thorley. Several years ago they changed the design due to cracking. They went with a 3" collector. I had an earlier one, which cracked and I had it replaced with the new style. You may want to look into that. They have a lifetime warranty, but they may try to charge you for the upgrade.

Hmm mines a 634-y or something. It is there newer version but I didn't think the collector was that big...ill have to check.
It's already coated but ill be decorating it through swain. Gotta weld some bungs on it and the EGR

So break in would be good on the dyno. And I knew it was varying 2000-3000 but I wasn't sure I should make full dyno passes on it.
By the sounds of it I can break it in, change oil. Then seat the rings, change oil. I won't be going off mileage because its only a engine dyno, not chassis dyno. So I would think 3 hours or so at varying rpm for rings?


Once rings are seated, give her hell? I'm very curious to test my motor with a 60mm, 62mm and now my new 75-80mm throttle body. I would love to test the variance between headers. I will port match my older style ho intake and then test with my newer curved style. I'm for sure breaking it in on the dyno. Just worried about the actual dyno portion....

Desertjr wrote:Hmm mines a 634-y or something. It is there newer version but I didn't think the collector was that big...ill have to check.
It's already coated but ill be decorating it through swain. Gotta weld some bungs on it and the EGR

Like this?:


I was wrong about the Throley collector. The new style is 2.5" (3 bolt flange) while the old was 2" (2 bolt flange). I had to look through some of my pics.

So break in would be good on the dyno. And I knew it was varying 2000-3000 but I wasn't sure I should make full dyno passes on it.

You wouldn't be making full passes during cam break in. I would let if cool off long enough to change the oil after the cam break in.

So I would think 3 hours or so at varying rpm for rings?

I don't know. Perhaps call your ring or piston supplier.

SilverXJ wrote:

Desertjr wrote:Hmm mines a 634-y or something. It is there newer version but I didn't think the collector was that big...ill have to check.
It's already coated but ill be decorating it through swain. Gotta weld some bungs on it and the EGR

Like this?:


I was wrong about the Throley collector. The new style is 2.5" (3 bolt flange) while the old was 2" (2 bolt flange). I had to look through some of my pics.

So break in would be good on the dyno. And I knew it was varying 2000-3000 but I wasn't sure I should make full dyno passes on it.

You wouldn't be making full passes during cam break in. I would let if cool off long enough to change the oil after the cam break in.

So I would think 3 hours or so at varying rpm for rings?

I don't know. Perhaps call your ring or piston supplier.

Gorgeous header, yup I got the older 2 bolt. Ill call and see if I can't exchange/ upgrade it. You said its prone to cracking? Mine looks identical except the collector.

Ad that coating is exactly what I'm after except they offer a bronze color good for 2600* I guess. I like its look, the bronze that is, although its a bit more!
Also is that wideband or get on the 6th runner! Any specific reason for that? Why not at the collector?

SilverXJ wrote:

Desertjr wrote:Hmm mines a 634-y or something. It is there newer version but I didn't think the collector was that big...ill have to check.
It's already coated but ill be decorating it through swain. Gotta weld some bungs on it and the EGR

Like this?:


I was wrong about the Throley collector. The new style is 2.5" (3 bolt flange) while the old was 2" (2 bolt flange). I had to look through some of my pics.

So break in would be good on the dyno. And I knew it was varying 2000-3000 but I wasn't sure I should make full dyno passes on it.

You wouldn't be making full passes during cam break in. I would let if cool off long enough to change the oil after the cam break in.

So I would think 3 hours or so at varying rpm for rings?

I don't know. Perhaps call your ring or piston supplier.

Gorgeous header, yup I got the older 2 bolt. Ill call and see if I can't exchange/upgrade it. Its never been run yet, still fresh in the box. You said its prone to cracking? Mine looks identical except the collector, so I'm curious the change?
Pending the cost and differences I may just do the collector myself. 2.5" should suffice for my mild motor. Unless I should go 3" and then neck down to 2.5 since exhaust will be hottest and move fastest at the collector? Cool as its going back thus necking back to 2.5"?

Ad that coating is exactly what I'm after except they offer a bronze color good for 2600* I guess. I like its look, the bronze that is, although its a bit more!
Also is that wideband or get on the 6th runner! Any specific reason for that? Why not at the collector?

Desertjr wrote:You said its prone to cracking? Mine looks identical except the collector, so I'm curious the change?

Yah, they crack, hence the change. I don't recall what else they changed though. But there may have been one or two other minor changes.

Unless I should go 3" and then neck down to 2.5 since exhaust will be hottest and move fastest at the collector? Cool as its going back thus necking back to 2.5"?

You will be fine with a 2.6" exhaust.

except they offer a bronze color good for 2600*

I don't see that on ther price sheet. http://swaintech.com/race-coatings/auto ... ice-sheet/ If there is a higher temp exhaust coating I'm going to be pissed.

Also is that wideband or get on the 6th runner! Any specific reason for that? Why not at the collector?

EGT, and 6 is typically the hottest cylinder.

Ill call back but I believe I was told hey could do it in grey, silver, black and bronze and was 2500 or 2600*.