blown Fe.

[machoneman]

According to the knowledgeable people I know, and my own experience with my supercharged engine, equating boost with compression ratio is flat wrong.  That BDS chart is extremely misleading.  Think about it this way:  Let's say you have a compression ratio of 8.5:1.  If you put 15 pounds of boost into the engine with a turbo, where you aren't losing any power at the crank from turning the blower, you will effectively double the horsepower output of the engine.  Does anyone really think that raising the compression ratio of the engine from 8.5:1 to 17:1, like the chart says will happen, will double horsepower output?  Of course it won't; the entire analogy is flawed. 

Jay, I hear what you're saying but.....the chart doesn't mention hp at all.

"This chart shows the final compression ratio combining the static compression ratio of an engine and the maximum blower boost from the blower system. It is to be used as a guideline in determining the proper maximum boost level for a specific application. Final compression ratios in excess of 12.4:1 are not recommended for use with "pump gas." The higher the final compression ratio, the higher the octane rating of the fuel must be in order to help prevent detonation and serious engine damage."

I've never read this or similar charts that way (i.e. hp production) nor the blown alky folks I knew and crewed for who do stand by the overall assumptions it makes. Simply, it's helpful in noting how those high overall total C/R's can get one into trouble unless they run non-gasoline fuels. The correlation of C/R's and  boost levels does exist even if the chart (or BDS's own somewhat expansive texts from the website on the matter) seem to be somewhat misleading....unintentional on their part, I'm sure.   

[jayb]

Bob, you have no idea how many people I've talked to who have jumped to the conclusion that raising the compression ratio is the same as adding boost to the engine, based on what that chart says.  And they also seem to infer that you have to run fuel for the compression ratio in the chart, based on your boost level, which is not true.  I'll stand by my comments on this one; that chart is a poor guideline to follow.

[machoneman]

Bob, you have no idea how many people I've talked to who have jumped to the conclusion that raising the compression ratio is the same as adding boost to the engine, based on what that chart says.  And they also seem to infer that you have to run fuel for the compression ratio in the chart, based on your boost level, which is not true.  I'll stand by my comments on this one; that chart is a poor guideline to follow.

Ah, I now understand Jay your concerns. I see, per your clarification, how folks have jumped, incorrectly, to assume a raised C/R is the same as adding boost. I agree, it's not the same.

I'll add that I also see now how the chart can be or is misleading for gasoline-fueled engines.....as opposed to alky/methanol/nitro racing engines which are of course a whole different animal.   

[fekbmax]

Sitting quietly,  learning. ..
 In just a few short days I know more now about blown engine's than I ever imagined.  The old school, the new school, and everything in between. I'm simply getting schooled by all you guys input on this and I greatly appreciate it.
Thanks guys..

[machoneman]

As Jay noted in an earlier post, for an FE your pal's best bet is to get his adaptor and a true 351C blower manifold. Although they are available from time-to-time on E-Bay, most recent 351C blower intakes seem to all be modified carb'ed intakes with that flat plate bolted on. While this would work, heck I say do it right with a  real as-cast blower intake. JMO!

[HolmanMoodyStroppeGang]

I have been thinking about your combo.

In the 60s, few ran a polished blower, so we hard anodized them. This is for cooling, a finely cast case has a lot more actual area to radiate heat and absob the coller ambient air, that was the thinking and it looks period

Also, you need to find a front cover to drive the fuel pump off the cam old school

I was thinking, JAYS cover could be adapted with a Hilborn or Enderle mount, just a register with 3 or 4 cap screws and a drive off of a grade 8 Allen Cap Screw

an old blower intake would look 60s

BUT, I want you guys to have fun.

Many guys started with port fuel injection, then a blower

Check this link out

http://www.hilborninjection.com/PDF/Hilborn2014_catalog.pdf


And check out the injected FORD in the front

See age 26 too

Mechanical fuel injection was very popular. On Alky, you run huge compression, get that guy popping crisp at idle

Big roller cam or a nasty old style flat tappet too

I'd ponder it as a logical step. You boys could haul the mail old school

And they are fun to fire up and tune. Kind if teaches you the ropes to later step up to blown and injected

Remember, the injected AFX cars flew boy I tell you.   Go check them out for inspiration

Fast fun period in FORD history. And don't panic, you can add some Nitro, 6%    12%. Mixes easy with ALKY. And hold on.   Guys went 200 MPH on a light load

Be well  Good luck

[Tommy-T]

I've been watching this post for a while now. I make no claim to be an expert on the roots blown FE...except that I have been sitting behind one for about 5 years now...and have hurt one by my own ignorance. It is running again and seems to be pretty happy.

My suggestions for an occasionally driven car:
Lock out the timing. Start at 28 or 29 and INCH-UP on it. Detonation WILL pound your "junk" into "garbage" fast. Roots cars like alot of "leeed"...so give it some.
Use a good quality HARD top ring. Alot of folks use steel even on the street. I'm using the Childs heat treated top ring. Hard as hell to file the end gaps. Make sure your bores are STRAIGHT
Run it pig-rich THEN INCH it back down. Molten pistons and scored cylinder walls are no fun. Been there done that. Didn't care for it.

I have no experience with cars that run on alky except to say I do have a Snow water/meth injection system on my car. Its set up to start a fine mist at 4lbs. and ramp up to maximum at 8lbs.

Hope you guys have fun.

[HolmanMoodyStroppeGang]

Great advice

Tommy T has a really nice blown FE and we hope to meet him soon.  (We looked 3 times for you at Knott's..LOL)

HE is a smart tuner and I agree if this is a street car. Use consistent octane fuel, then dial it in real safe, and real patienlty

Rich is safe, and bump the mag from a real safe spot in baby steps, while wtching the fuel curve and plugs.

GEt her rich until she slows down and the plugs look dark and safe, then back it up in little lean steps and be consistent as you tune it. Stay on the safe side of perfect, lean to a little rich from perfect for a margin of safety on the street

She may build a ton of heat one Summer, or you may get punk fuel

Stainless top ring, smart.  Ran them in blown SOHCS in the mid 60s, but a DYKES

Never hurts to wire in a knock sensor if you can't hear detonation real well, some can, some can't.

If this is a Drag car, he has carbs, look into mechanical fuel injection or EFI maybe

You can do carbs sure, but 8 nozzles upstairs in a hat(Injection scoop) or similar EFI can be a smart way to go

We run nasty blown stuff on race gas around here on the street

Here's a trick.

You dont have to squirt the injecter like at a race, no need to carry a priming bottle


We have a safe priming buttion, like you use on a hot boat that has constant flow fuel injection.  You just push that big button,1,2,3. spin it, flip the mag on and rat a tat tat tat

What is COOL about a blown gas car, with a gear drive, is that when you wing it, or rev her, then lift, she makes that good old WIND as she unwinds, and revs down


ZOOM, wizzzzzzzzzzz

Just like  the AA/FD's of old

That Vroom, lift, wizzzzzzzz(gear whine) as she slows, really brings some old guys back to the Drag days of old

have fun, Tommy has my vote for Crew Chief. He'll dial ya in  !!

Final thing, read them plugs a lot !!  Once set, and dialed in?  Easy street. Just mash the gas and hold on

blown gas is an easy way to get 3 horsepower per cube

Thanks !

[Faron]

Mine is almost back together a week or so and some polish and back in my 68 it goes

[machoneman]

Cool! Let's see it again when installed.

[HolmanMoodyStroppeGang]

Looking cool

Looks like she will be ready for many more miles of fast fun !  Nice job man, looking all force fed and fun.

I bet that the guys would enjoy the build specs and tune up data to kind of ponder?

She looks pretty close to straight up? Around 1 to 1 ? And I see a pair of Holley's very cool, maybe 660 center squirters?  How much jet?  Bet the guys will enjoy that, more jet, burned well, is fast !

Nice looking aluminum heads, and all the details, looking cool man

So, how much static compression? And how much is the down? Maybe 250 down flat tops?  WHo's slugs?  Standard stainless top ring?

Does she run a mix of pump and good gas? or just good gas, or pump premium?

How much advance? And is she locked out or a quick short curve and a lot of initial?

I think these guys might learn by getting closer to good combos.

Ever read the boost at WOT?  I bet these new blown FE guys would learn some basic tune up talk if they get a boost target in pounds, you know?   Like, she is set  safe safe, I usually run 'x' pounds of boost, she sees 5 pounds, but I have a race gas tune up, I change the pulley and run...10 pounds...you know.... then they can kind of gauge their goal a bit


If I recall, you ran this street combo forever, so maybe if they learn the specs a bit, and how reliable she was, they might feel more confident from the start, any maybe learn the car and power level with it backed down to the safe and reliable zone.


Blown combos come in may shapes and sizes, from very streetable, to hot street strip, needing race gas only, to hot drag tun ups, to max race on gas combos

Some people forget, that that 6-71 GMC Jimmy, the old roots, came off of long haul, super reliable trucks that ran and ran forever in industry.   Some people figure, blower, top fuel, boom a lot, and tear down every run. On Nitro, sure, on gas, much much more mellow


I am not sure of their direction here, but I am sure, that we did many many blown FE's at the old Holman Moody Stroppe shop, and many with very efficient single and twin turbos, and I sometimes wish that more guys added a blower to their FE

It is an easy way to dial in, power, and, tune her up and down

2 Horsepower per cube can be done real well, and if you want to run her hard as can be, much more is there in a race setting

They also have the water methanol option, if they chose pump gas and some street heat

And as you and many guys know here, they can add a safety net, with a knock sensor, and retarder as part of the ignition map, and amp.

It was huge when MSD and others began making retard function boxes for a lot of blown guys.

Looks real cool and pro built. Who's blower cam? 

Hope many more guys get a huffed FE from you for their Hot rod

Who does your blowers? Maybe they can use your blower shop. Not stripped since she runs so long, or?

Thanks man

Nice job