Me n Ethyl out cruising today when a Camaro spied us out on the IH. We was on the access road. played a little. enjoy
Now THAT looks like fun!
48 Plymouth Custom Special - 4dr suicide style
Starting new build from scratch with plans of:
1950 Chevy straight axle with steering box
Ford 9" rear with 4.10's or 4:29 gear
Mopar 440, 512 CID stroker estimating 680 - 700 hp on pump gas
30 or 32 inch X 10 wide tires
guessing at finish weight of 32-3500 pound car
hoping to run in the 10's
This project will be the quickest vehicle that I have built so I am really looking forward to it.
So, after a ton of work I finally got the Hot Rod on the Dyno Monday. I watch way too much YouTube and Facebook so I had a number in mind. The new engine just felt like a beast compared to the old engine. My oldage memory recalled a 320 number on the old engine and I recalled that as horsepower with a larger torque reading. The new Holley Sniper had greatly improved drivability over the old carburator setup. I engaged John Gilliland to put a tune on the Sniper, we were running the basic Sniper self learned tune on the new engine until Monday. The tune itself goes into dozens if not hundreds of areas of the engine, fuel, spark, and air combination at the entire range of engine speed, temperature, air density, and a number of other variables the new Sniper has provided sensors to measure.
The first few pulls were well below 300 HP to the Wheels with Torque in the 320-330 range. That set the baseline. John went to work changing the timing and fueling, improving the driveability incredibly. Still the numbers only came up into the 320-330 wheel horsepower range though the torque did manage the mid 330's. Studying the pulls and John's seat of the pants intuition, we determined the Wheels were not hooking up to the dyno at all. After the tweaking, which included the fat guy sitting in the trunk, we did a final that netted right at 343 rear wheel horsepower and 358 foot pounds of torque. It was a general improvement in the numbers. But I was somewhat disappointed as my expectations were higher. I really had no idea of how good these results were.
First, going into the session I had no idea what the redline for the new motor was. We saw a clear falloff at 6200 RPM so that is where we set it.
Second the engine suffered an overheating problem with the old setup, often reaching 240 degrees on hot Texas days. On the trip out before the tune we averaged 190-195 degrees, showing a remarkable improvement over the previous engine. With the tune adjustments to idle and cruising timing, on the return the temps dropped to below 170, meaning I need to up the thermostat. The car cruises at about 185 degrees now as opposed to 192 prior to the tune.
Also on the way out I averaged 9 miles per gallon. On the way back with the new tune we averaged 14.5 miles per gallon figuring a near 30% increase in economy while cruising. Of course when my foot gets involed that gets worse sometimes.
My exhaust was designed for a 190 horsepower sbc crate engine with 2" collectors and tubing. The headers are 1 3/4 tubing. I need 2.5 to 2.75 inch headers with 3-3.5 inch collectors and 2.5 inch exhaust piping. Just my opinion
I installed an adjustable 4 Link system a few years ago and have never really gotten that effectively dialed in. I am old and don't bend so well. I don't have access to a rack to take the 4 link adjustable settings and properly set up the pinion angle. That may well have been a lot of the problem with the traction, though light weight needs to own some of it. I need to pay attention to that.
Overall drivability is excellent after the tune. John did a great job. Holley Sniper provide an okay daily driver safe solution and the learning keeps the finicky fuel tables up but the touch of a tuner smoothing out the timing and fueling transitions is a big improvement. In the photos below there are three sheets, two from the old engine done in 2016 and 2017 and the third is from the latest session. All in all a 50-55 rwhp gain and a 36 rwtq gain. Over the 2017 session and an 81 rwhp gain over the 2016 session. Enjoy the dyno, no surprises in it, just a bunch of pulls.
Sounds great Bill. Nothing like a Hotrod that gets good mileage too.
"I post the work on my hotrod, not because it's the best way, rather it was the way I had to get it done with the resources I had.................
Of which I might be an encouragement to other hotrodders".
With those RWHP figures that's a very good flywheel HP number for a SBC. I'd guess it's getting up in the 450 hp range or maybe a bit more at the flywheel, which is darn good.
Don't recall if what your trans is, but if it's not got an overdrive then that mileage is awesome for a 1:1 top gear. An overdrive would make highway mileage boost about 30% higher.
Its got a T45 5 speed, 5th is 0.67 I have 3.73 rear gears with 27 inch tires. Here is another short romp or two.
With the 5 speed T45 you should get pretty good mileage when cruising at highway speeds. But of course you need to be steady cruising, vs. hot footing it to get the mileage. The T45 is just about at it's limit of 400 ft. lbs. torque with your engine build, but the lightweight of the car helps a lot.