[Jack Gifford]

First, to agree on terminology- your 10-71 has a displacement of 511 c.i. (same as a standard-helix). It will not move 511 c.i./revolution at any pressure higher than zero. The high-helix is more efficient, so will move more air-per-revolution at a given pressure.

My 14-71 is a standard-helix, central outlet (not the 'retro' deal). I originally planned to use an 8-71, but decided I'd rather spin a big blower slower than the 15,000 the 8- would need to turn. I'll initially run the blower 29% over crank speed, expecting about 30 PSIG manifold pressure

As for the numbers- try plugging 4.4 HP/c.i. into simulator software and see how much Roots blower you'd need with your 475 c.i. to make 2,090 HP on methanol. Of course If my 56-year-old head flowed more than 340 cfm, not as much boost would be required; or if I lifted the valves more than .700" (or more aggressively).

[twooldgoats]

Originally Posted by Jack Gifford

...
As for the numbers- try plugging 4.4 HP/c.i. into simulator software and see how much Roots blower you'd need with your 475 c.i. to make 2,090 HP on methanol. Of course If my 56-year-old head flowed more than 340 cfm, not as much boost would be required; or if I lifted the valves more than .700" (or more aggressively).

^^^^^^^^^^^
There's the answer to my question. I'm making 1200-1300 HP currently. Are you planning 2,090 HP for your 4-cylinder or half that? My software had one purpose only: to match air flow and fuel delivery. I didn't plug in HP or boost levels and try to achieve those. I worked out the air/fuel ratio I wanted (approx. 4 to 1), made sure I got that going down the track, and let the HP and boost go where they wanted to go. In other words, I had an A/F ratio goal ("don't blow up the engine"), not a specific HP goal. If you're working toward a HP goal (move an X-pound car at Y-mph on a long, straight stretch), that's a different deal. I used other people's experience to know I could reach my goal (seven-second quarter-mile times in a 3000# door car shaped like a brick), if I used a 10-71 and didn't scatter the engine.

Thanks for the info.

Jim

[Jack Gifford]

I'd be thrilled to do nearly as well as you've done with your blower motor, Jim. It won't surprise me if the power numbers of my simulations are way off. But over the years the simulations have helped shed light on expected results of various combinations of details- tweaking valve timing & lifts, blower efficiencies, head flow, etc.

My present goal is in the neighborhood of 800 HP. The former car owner had a one-way run at Bonneville very near the 263 MPH record in the class I'll run; his engine had been dyno'd at 725 HP.

[twooldgoats]

I'll bet it really helps that there's a history of your car for you to turn to. That would help make up for the difficulty of trial runs when you get it running. I just had to tow my car 20 miles to my local track and make passes to my heart's content, until I met my seven-second goal. Even at that, it was four trips to the track (over a period of a month) and eight passes until I ran my first seven with the supercharger. As it is, I wasn't breaking any new ground with my car, just meeting a personal goal, following in the footsteps of a lot of guys before me.

Your task will be a lot harder. I imagine there are only so many opportunities to get out and see how it goes. It's not like driving to the local drag strip.

Keep us posted on your progress. It's fascinating to me.

Jim

[Jack Gifford]

It feels good to FINALLY begin actually assembling the engine!

But assembly will still suffer delays to verify stuff. With just the crank installed (no pistons/rods yet) I'll phase the two cams to each other and check valve-to-valve clearances during overlap. Then- if the 5HP electric motor will spin the crank & cams, I'll observe the complete cam-drive/valvetrain in motion.

[Jack Gifford]

All of .030" between valve lips during overlap. What... me worry?

[mgarblik]

Jack, if you are referring to valve edge to edge clearance between them, you may want to PM Eric and discuss some issues we had in actual operation. On the nitro car, the required loose guide clearance and the extreme heat of combustion, caused some edge to edge contact in our engine at high RPM. We had .050-.055" separation cold but the valves still got together at speed and operating temp. We were very surprised. We had to reduce exhaust valve head diameter, and increase stem diameter to solve. Your Hemi with OHC, shorter stems and lighter weight, may be fine. Just wanted to alert you. In our engine, the damage was minor, slightly bent some valves and lost a quality seat seal. Keep up the good work.

[Tom Vaught]

Bonneville is not looking so good again this year, as far as salt condition, Jack.

"Salt Report from USFRA president Dennis Sullivan
The following is what Larry (Volk) and I found out on the salt Saturday 6/25/16.

Even though we were able to find a short course north and east of the Saldero Loop, the area around the access road out to the bend in the Saldero Loop is wet and the salt crust is so thin that we don't think it will hold up.

The support traffic for the race vehicles over the 4 days of the test and tune event (registration/safety inspection and 3 days of racing) would cause long term damage to the area around the access road and around the starting areas of the existing number 1 and 2 courses.

Even though the USFRA would like nothing better than to provide a Test and Tune opportunity, I feel the risk of damage to the salt flats at this time outweighs the desire for the Test and Tune event.

With some more drying time and a little help from mother nature, later in the year events may be possible."

Hopefully, Jack, in the later part of the year, there may be a chance.

Tom V.

[Jack Gifford]

Mike- thanks for the heads-up on your experience with valve collisions. My engine shouldn't have much walking-off-center of the valve heads- intake stems are 11/32", exhaust 3/8", length is fairly short down to the guide, largest head (intake) is only 2.030" diameter, lobe profiles are "gentle", lift only .700" at valve, and it's not an extreme environment like your fueler. That .030" is with lobe centerlines at 108.5 degrees. Since I can individually time the cams, I may decide to open the centerlines up a little bit- I need to see what the simulator software says about a wider centerline angle, regarding the [expected] torque curve.

Yes Tom, the future of Bonneville racing is unknown. Fortunately for me, pavement LSR is gaining popularity- Wilmington, Loring, Mojave Mile, Texas Mile, etc. My intention all along has been to campaign the car mostly on pavement.

[Elarson]

We decided that it was a dynamics problem with the exhaust valve, since we couldn't account for the loss of clearance from valve guide clearance and thermal growth of the head.

Our combination of valve weight, overhung length beyond the guide and loss of modulus of elasticity from the extreme temps must have created a vibe mode in the operating range.

Eric

[Tom Vaught]

Originally Posted by Jack Gifford

Yes Tom, the future of Bonneville racing is unknown. Fortunately for me, pavement LSR is gaining popularity- Wilmington, Loring, Mojave Mile, Texas Mile, etc. My intention all along has been to campaign the car mostly on pavement.

Do not know if they will still have the "OHIO Mile" when your car is ready but the TEXAS Mile will still be there and as you said, several others are coming on line.

Good Luck with your engine.

I ran across an old magazine, believe 1961 time frame with a Mickey Thompson roots blown 4 carb (side-drafts) on the cover. 1961 might have been one of the first 421 engines by Mickey in the press. You know anything about that engine, Jack?

Tom V.

[Jack Gifford]

Thanks Eric. With my luck, there just might be some oddball harmonics lurking in my engine also! I may initially be more cautious and spread the lobe centerlines more than just a deegree or two.

Tom- I think you were seeing the show car that Mickey helped create for Pontiac. A '60 Catalina hardtop with some custom bodywork. The side-drafts (on a 4-71?) were a neat solution to keeping the original hood line. I've forgotten most of what I once knew about it.

[Jack Gifford]

Changing from 108.5 degree lobe centers to 112.5 degrees (easy to do with dual cams) improves the worst-case valve-to-valve clearance to about .054". And, surprisingly, engine simulator software shows very little change to the torque curve- if it's to be believed. Anyway, I'll be cautious and set it to 112.5 degrees, at least initially.

Tom- was it the XP-400 that had the side-drafts on a blower? I think (?) that the engine was nearly stock, with just some M/T pieces- pistons, etc.

[Jack Gifford]

Engiine assembly going well. Used the electric motor to turn the whole longblock at about 700 RPM for a few seconds- just long enough to let the valvetrain "settle in" before a final check of valve clearances (no oil supply, just depended on generous coating of assembly lube on all surfaces). Need to build a crank scraper and fit a windage tray. The blower manifold is still at the welding shop. Then I'll do a trial-fit in the lakester to look at clearance in the area where the magneto and pumps will be driven off the rear of the camshafts, before fabricating mounts for them.

[Jack Gifford]

Ready for a ride to Norwalk. Will be on display in the midway.

[Drag Star Le Mans]

Looks good!

[mgarblik]

Look forward to seeing the engine. Talk about exotic!

[Elarson]

Thanks to Jack for loading up the engine and making the tow to Norwalk. Fascinating guy to talk to....

Eric

[mgarblik]

I also want to thank Jack for bringing this engine to Norwalk. I have now seen the engine and the Lakester. Next is to see the two married together. When this car goes to the salt or asphalt, it will be exotic history in motion. A museum quality car with a virtually hand built, historic engine, evolved to modern DOHC efficiency. Jack opened the engine up so some of us could inspect the internals. The design and attention to detail for a land speed run is extensive. This is a serious piece unlike anything I have ever seen. Plan to be wherever it debuts. I will post some pics soon.

[dci]

Jack, I feel so bad I couldn't get over to see and meet you. Your little monster looks incredible and man I would have loved to seen it in person. I had such a busy week and weekend that I just couldn't get caught up. You were at the top of my list to visit and it just didn't happen. I'm sorry !!!!!! Please keep us posted when you get that thing in the car and some runs under your belt. Looks KILLER !!!!!!