jimbo3

That clears it up. Thanks!

element

Is this something i can do at home? Any suggestions on equipment i would need?

MarkD

sure, it's far from rocket science

you need relatively high volume air compressor
and a leakdown gauge set

they can be found for under $100... But I am not sure of the quality/accuracy of these gauges.
However, for a one time, home shop test, just about any gauge skillset likely do the trick
That said, investing in a good quality tool is never a bad idea!

When doing a leakdown test on these engines, there is an element of cross cylinder comparison, much like a compression test. Even if your gauge is off by a % or two, you are also looking for a deviation from the norm. In short, you want to find out how much air slips past valves and rings and look at the results across cylinders. If one cylinder is showing 15% and others are at 5%, listen carefully for where the air is exiting. That will ID the culprit.

MarkD

exactly, I wouldn't use an automotive tester on an aircraft or diesel train engine...
I suspect there are specific testers (and more $$!) for these applications

philchil

can a dyno test be used in place of a compression and leak down test.

Cost of a dyno is $75....cost of a comp/leak down could be 5 to 10 times the cost...

So, if the dyno reflects a strong engine...smooth trend lines to redline, with near stock numbers in HP and torque...would not a dyno test be an 80% answer to the health of the engine?

Thoughts from the experts out there?

IXLR8

You have a PM.

IXLR8

High volume or high pressure (over 100 psi)?

I don't see needing a lot of volume in this application since we're not flowing air past anything more than a 1 mm restriction...and hopefully no air at all.

race911

Who/Where?

My thread from last summer: https://rennlist.com/forums/showthre...ferrerid=21505

Steve Weiner-Rennsport Systems

Nossir, not at all. Leakdown testing is considered a diagnostic test and dyno tests are dynamic.

An engine can suffer some leakdown issues and surprisingly, can still make good power. Bent valves will cause a noticeable rough idle, however broken rings will not always make a difference you can immediately feel.

Leakdown testing is akin to getting a "physical" on your engine.

TMc993

Awesome thread....

MarkD

I said relatively high volume
a small nail-gun type compressor would be less than ideal
may be possible to use but not the right tool for the job

you need to be able to produce 100 psi consistently to get good readings.
there will be a constant airflow, even at a few % leakage

race911

Personal experience, no doubt. Was for me one time when I'd set a lap record for the class in time trial; and a couple of weeks later casually poking around found 2 bent valves and a piston with broken rings + lands.

philchil

Thx Steve and Ken....guess either mis information or overcharging when I got my estimates in LA...One hour labor charge would be cheap to get that info.

I just got my rsa dyno'ed yesterday...got 243 hp/228 lb ft torque...have a cup primary bypass and a Wong chip....got 59k miles on the car.

Getting my rs clutch/flywheel installed in two weeks...guess I should get a comp check and leak down when it's in the shop...

NC TRACKRAT

From my amateur perspective, if, after taking the compression test first, you get good psi in each cylinder and very little variation from cyl. to cyl., a leakdown test is not really necessary. Only if you see poor compression across the board or low compression in one or more cyls., then a leakdown test would be warranted because you want to isolate the source of the poor compression.

race911

At the wheels, or corrected? (I've never run a car on a chassis dyno.)

But once you've got everything apart anyway, it's only a couple of minutes per cylinder.