The cam and headgasket video is up. It's a bit of a long one though, there was a lot to cover.
Dyno Testing Bolt-ons On The 4.0
- Thread starter Jezza
- Start date
Maybe I missed it, but I'm assuming you installed new piston rings, right? Did you hone the cylinders?
Very interesting results with the roller rockers. I'm curious what a set of 1.6 ratio roller rockers would do. Alas we will never know (for this project anyways). Thanks for having your dyno go out with a bang for us TJ guys!
Anybody want to email the YT links to Jerry?
Maybe I missed it, but I'm assuming you installed new piston rings, right? Did you hone the cylinders?
Very interesting results with the roller rockers. I'm curious what a set of 1.6 ratio roller rockers would do. Alas we will never know (for this project anyways). Thanks for having your dyno go out with a bang for us TJ guys!
Anybody want to email the YT links to Jerry?
No new rings and no honing on the cylinders. The finish was still good and the crosshatch was still sharp. The pistons I had were almost new. Less than 30k IIRC. They still had the coatings on the skirts. I am of the opinion that even used OEM rings are probably better than most new aftermarket sets.
Maybe I missed it, but I'm assuming you installed new piston rings, right? Did you hone the cylinders?
Very interesting results with the roller rockers. I'm curious what a set of 1.6 ratio roller rockers would do. Alas we will never know (for this project anyways). Thanks for having your dyno go out with a bang for us TJ guys!
Anybody want to email the YT links to Jerry?
That has actually been tested before. At least on a stroker build.
Yep, that's why I was curious. They seemed to have gotten more with the stock ratio than Jezza got with the 1.7s.
That was a sad video to watch, rockers under performing as a bolt on and the big no more dyno mic drop.
Good side it was great video to show case some of you & your shop capabilities to get that engine out, disassemble and back on the dyno to post some more strong pulls.
That motor had peak torque up at 4500rpm where the stock setup on the 4.0L peaks at 3200rpm give or take. They also took it up to 5700rpm where Jezza's stock 4.0 was breaking up at 4800 or so. Same block, very different builds. This is one of those where I really wish the curve started much lower around 2000 or 2500 rpm where we usually drive these 4.0s so we could see a more full picture and that the charts provided more resolution.
Crank hp <> Wheel hp and a TJ definitely doesn't seem to be on the efficient end of that spectrum. Alot of the dyno runs I've seen show a starting WHP around 133-138 which is around 30% driveline loss from the generally 190hp rating on these..
You should see the driveline loss when you throw in an Atlas, Tonz and Fodeez...
You should see the driveline loss when you throw in an Atlas, Tonz and Fodeez...
I was wondering about the gear driven Atlas vs a chain driven stock T-case with regard to drivetrain loss yesterday. Chains are more efficient. In the mountain bike world, various gear box designs pop up now and again but they always suck to pedal.
Chains and gears both can be quite efficient. Going from chain to shaft drive introduces losses mainly with 2 90-degree gearsets. A better comparison would be a bike with a belt drive (or single-speed chain) and gearbox.
I don't know of any actual measurements, but I wouldn't expect much difference with the atlas in high range. The bigger the ratio change the more energy is lost, so a 5:1 low range will turn more horses into heat than a 2.72:1.
Good point. In 2H on the street or on a dyno, power is going straight through the box, so presumably not much difference.
With regard to a bike, I had one of my single speeds set up with a Gates belt drive for 10 years. When I rebuilt it, I went to a chain for other reasons, but the chain was immediately noticeably more efficient feeling to my thigh dyno
. Many years ago on a different bike, I ran a crankset that had a helical gear low range (instead of the the normal at the time front derailleur to switch between chain rings). That also had very noticeable drag. No bueno. I’ve read articles on the topic of drivetrain efficiency in bikes and essentially nothing beats a clean, dry chain.Moving back to the automotive world, I would assume power loss with gear driven transfer cases in low range as you point out but also gear driven cams.
Thankfully , not many dyno. runs are in low range.
The dyno is already gone. The LJ engine still has some cam bearing issues, so I leave it at 10 psi. I need to pull the engine and find out why it keeps chewing up the cam bearings.
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