At what EGT do you let the magic smoke out?
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Mutt The Race Truck
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Dunno - hasn't happened yet. My buddy Steve Menendez has a LOT more experience with little Diesels than I do and he says 1600F is the time to lift the right foot no matter what else is going on (he's fragged a few at Bonneville). More and you'll decorate the track. I believe him.
DanLast edited by DanStokes; May 21, 2019, 07:33 AM.
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I had a friend who bought a Dodge cummins truck that was turned way up. It had no gauges and the diesel stuff wasn't popular like it is now(2001ish). After some research he decided to put a boost and EGT gauge on it. He called me after the first test drive, "it pegs the boost gauge........and the EGT guage" lol. He never did anything about it, but I am sure 2000* is OK for a 1/4 mile run but no way for a mile much less 5.
What is the ultimate speed goal for your truck? I have enjoyed following its progress on here.1968 Plymouth Barracuda Formula S 340 with a 360
1997 Jeep Cherokee off road toy/driver. lifted, lockers, stroked 4.0
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Originally posted by BlueCuda340 View Post
What is the ultimate speed goal for your truck? I have enjoyed following its progress on here.
And thanks for following along!
Dan
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As has been mentioned elsewhere on BS, Mutt's engine is out of RPM at the top of the track and it's time to swap rear gears. I've been running 3:08s (well, actually 3.076xxxxx) and careful math shows that Mutt ought to run 136 with a 13.7" tire radius which is probably about right with a 28" tall tire under load. And we're running a best of 136ish - right on by the calculator. So I'm going with 2.73s which predict a top speed of 153 - assuming, of course, that I have enough engine to turn the tach back up to full speed.
Anyhow, here goes with a few pics of the job in mid-stream:
I blew the whole deal apart before I took pics so before this shot I had drained the rear, pulled the axles (with C-clip eliminators you don't have to pull the C-clips - a good thing), then removed the carrier and pinion.
Here's the old Ring and Pinion sitting on my extra work table (looks a lot like a table saw when not being a bench). These will probably never be used again but I have a set of 3:08s if anyone needs them and they look to be in good shape. BTW - 7.5" GM ring gear bolts are LEFT HAND THREADS! Broke 2 before I figured that out.
Here's the new stuff along with the installation kit, all from Richmond Gear. Good stuff. The bearings on the pinion are the old ones that I ground out the interference fit so David Rackley and I can set up the pinion depth and tooth contact pattern w/o pressing the bearings on and off. I was worried about getting the ring gear aligned with the bolt holes but it turned out to be fairly simple as the bolts are long enough to start before the ring is on the step that it presses onto. Note all the bearings are in place thanks to my trusty HF 12 ton press.
BTW, the installation kit is SUPER complete with extra shims, the ring gear bolts, etc, etc. Worth the $93 from Jegs.
Rear view of the housing all cleaned and with the new races in place. I mis-used the HF front bearing tool set to drive in the races and it had the right size drivers and worked fine once I abused the installation screw with a hammer to pop them in.
Front view, same deal. Note that the driveshaft is just hanging out on the driveshaft loop - so far so good but we'll have to see if David wants me to remove it.
A race vehicle is NEVER "done".
Dan
Last edited by DanStokes; May 21, 2019, 07:35 AM.
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Looks a lot like the Ford rear! Where is the quick change? Rule of thumb I heard is 300 hp to run 150 mph in the mile. I would love to see Mutt run 150! .35 gear change is pretty big. My old Capri ran surprisingly well with a 2.47 gear, 143 on the frist and last full throttle pass. That Mark VIII didn't like the gear (larger tire size) as much. It picked up but never hit the speed limiter. I aways wanted a car with a quick change. Playing with gear ratios is fun math!
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Originally posted by Russell View PostLooks a lot like the Ford rear! Where is the quick change? Rule of thumb I heard is 300 hp to run 150 mph in the mile. I would love to see Mutt run 150! .35 gear change is pretty big. My old Capri ran surprisingly well with a 2.47 gear, 143 on the frist and last full throttle pass. That Mark VIII didn't like the gear (larger tire size) as much. It picked up but never hit the speed limiter. I aways wanted a car with a quick change. Playing with gear ratios is fun math!
As far as a quick change - the operative word is "change" as in, I don't have enough change to make that happen! Otherwise I'd be calling Joe Timney for a Winters. But math is NEVER fun for me! I found an online calculator that only requires me to enter my numbers and it spits out the result - just my cup of tea!
Dan
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I have done spead sheets and I have a program in my calendar. I normally don't work it out long hand. But can if I need to. Unit conversions are easy to mess up. Rather solve a math problem than write a paragraph any day
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Hey Dan have you thought about running a couple of different diameter tires (not at the same time) or is that too subtle a change? I know mutt is pretty low so maybe a 29" is out but with the new gears maybe a 27" if it wont pull with the current 28".
Just thinking on my keyboard SteveWell I have stopped buying stuff for cars I don't own. Is that a step in the right or wrong direction?
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Originally posted by rightpedal View PostHey Dan have you thought about running a couple of different diameter tires (not at the same time) or is that too subtle a change? I know mutt is pretty low so maybe a 29" is out but with the new gears maybe a 27" if it wont pull with the current 28".
Just thinking on my keyboard Steve
Dan
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Originally posted by DanStokes View PostAs has been mentioned elsewhere on BS, Mutt's engine is out of RPM at the top of the track and it's time to swap rear gears. I've been running 3:08s (well, actually 3.076xxxxx) and careful math shows that Mutt ought to run 136 with a 13.7" tire radius which is probably about right with a 28" tall tire under load. And we're running a best of 136ish - right on by the calculator. So I'm going with 2.73s which predict a top speed of 153 - assuming, of course, that I have enough engine to turn the tach back up to full speed.
What speed will you make in 4th at the governor with the 2.73s? - I can't remember if you have a 4-speed or 5-speed trans?
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Originally posted by Red_Kitty View Post
Hi Dan
What speed will you make in 4th at the governor with the 2.73s? - I can't remember if you have a 4-speed or 5-speed trans?
David is postponed 'till tomorrow but I'll post pics when done. I also went nuts and ordered the stud set for the carrier bearings (T/A) along with one of their rear girdles. The girdle is scheduled to arrive tomorrow but we'll have to do the setup with the carrier bolts as I don't have a ship date yet for the studs.
Dan
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I like the more boost route! Can you turn up the fuel as well or is it rich now? I really don't understand how they meter fuel.
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I have PLENTY of fuel and more is available if I get to the point of needing more. The Dieselmeken pump is HUGE as compared to the stock one.
The big turbo that I installed last year also has a lot more left in it - I suspect I could run 60PSI if it comes to that. The interesting thing is that as I add boost the EGTs come down as evidently overfueling adds to EGT and having enough air (oxygen) to satisfy the fuel cools everything down. This is Steve Menendez's (Salty Frog Racing - the frog green Rampage) observation and so far it's spot-on.
Dan
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