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Since it's getting near the end of the school year...

For something different the M37 is hitting the dyno today. Anyone care to hazard some guesses? It's stock. We're using a Superflow dyno which are known to be conservative. I'll post the results and hopefully some photos this evening when I get home.

Post your guesses !!!

At the rear wheels I'm going to guess on a good used truck about 58HP. Now torque I have no idea as that is where the 6's shine.

54/106

Going on the dyno 1st run - 49, after tuning & adjustments - 55.

Interesting post.........make sure you tell us what you did to pick up those extra 6 hp!

regards,
bob

And the winner is: DCook w/ 49 HP!

47 HP, 123 Ft.-Lbs.

We just played around with the truck today to see how it responded to the abuse. Here's what I can tell you from the runs we did:
* Hot oil is good, to get hot oil is not easy in these things, even with a 180F t-stat. You need multiple back to back runs to get it warmed up. This is similar to the Mustangs we play with in the shop. Mind you the HP spread was about 4 HP.
* We did one timing change, 0 BTDC to 8 BTDC, no big difference. The oil at this juncture was more important.
* My governor was nowhere near working! It's adjusted now, but I want to toy with it a bit and see how it changes engine response.
* My NDT's and Budd's are not all that round .
* My !#$%@ fuel pump is leaking oil at the pivot arm. Any ideas? I was thinking 290 Loctite. We rebuilt it and solved almost all the leaks...

I'll update this with anything interesting. If you guys have any ideas the truck's lashed down and ready to go.

Andy

Hi Andy,

Great stuff. What weight oil are you running in the motor? If your governor wasn't working, what was the max RPM you ran it to? At what RPM was peak HP and peak Torque? Any chance we can see the curves?

thanks,
bob

Awesome! Post up more details...

Bob & CSCameron,
I'm running 20w-50 VR1 Valvoline. I may try something thinner, but wanted to see how the motor ran first. I chose the thick stuff for a bit of safety margin. I may go thinner next oil change.

As far as runs here's what we did, not perfect, but a first cut:
4th Gear, 20-60 MPH, 6.7s timed run. With 4:89's this should yield a run from ~1000 RPM to 3000 RPM. The plan was to get 300 RPM/s for consistency. This is the typical rate of acceleration we run on street cars. I found that the truck is not capable of 300 RPM/s... It's hard to look at data and teach at the same time! Ooops!

Our runs timed out prior to reaching 3000 RPM, but I don't think that's too big a deal. The power curve at that point was pretty flat. We'll adjust things tomorrow.

Peak torque was typically about 1500 RPM, peak power 2600 RPM (timed out, but pretty flat curve).

As far as the governor, when we started it was not doing any governing at speeds I saw! The engine would rev to 3400 RPM and I suspect higher. I adjusted it to stop the party at a tick over 3000 RPM. I want to play with it a bit tomorrow if I have time. Seems to work OK now, but when I drive into it in 4th I can drive through it. It does not do this in the lower gears. Not sure what's up here, may be the test method. I've adjusted it according to the Carter manual and it works fine if tested according to that, but they don't have a test for 4th at top speed with light load.

Once I get everything sorted and consistent I'll try and post the curves. I'm not sure how much "tuning" there is to be done. I'm going to try some timing sweeps and maybe pull the air cleaner. The AFR is pretty damn good for a carb that we haven't touched and still has some safety wire on it. It's in the 12's at max torque and leans out a bit to the 13's at max hp. I don't have any jets so my tuning will be limited. I guess I could monkey with float level... I will say I have not seen it run leaner that 14, even at light loads. Maybe there's some MPG to be had . Then again I don't think it ever runs at light loads...

Like I said, if anyone has some ideas post 'em!

Andy

You can set the buffers to record longer and not time out with the SF software. Do you have the eddy current unit? Would be cool to set it a 45 mph and slowly increase the current in the eddy unit until you stalled or started slipping tires.

I'm changing the run's parameters today so the accel rate is a bit more "M37 Like". Maybe 50 RPM/s!

6/4 Edit: No runs today, too much other stuff going on, may try a few tomorrow.

it would be cool to see what you get with a 4 blade fan

RMS,
The truck has a 4 blade fan. Isn't that normal? I may run it w/o a fan at some point to see how much HP it eats up. It seems to be overkill for the conditions I use the truck in.

I drove the truck home tonight and the governor adjustments made a significant difference in response. I didn't realize how much this thing has in common with a Briggs & Stratton until I started adjusting it!

Andy

I didn't realize how much this thing has in common with a Briggs & Stratton until I started adjusting it!

Ouch! That hurt!



bob

ashyers wrote:RMS,
The truck has a 4 blade fan. Isn't that normal? I may run it w/o a fan at some point to see how much HP it eats up. It seems to be overkill for the conditions I use the truck in.

I drove the truck home tonight and the governor adjustments made a significant difference in response. I didn't realize how much this thing has in common with a Briggs & Stratton until I started adjusting it!

Andy

I believe the 4 blade is stock. I would not be surprised if some variants had different fans for different accessories? My truck has all the 100 amp electrical for radios, but it still has 4 blades.
Please explain further, the adjustments you made to the governor, and the results you mentioned in drive ability?
Thanks
Dana Cook