Beach Dude

All right, after reading projects from 542C2, ML67, 427HOTROD, I think I have decided to upgrade the Merlin to a 8-71 Dyers Supercharger. Any interest or similar projects going on out there? I need to get the digital camera fixed or replaced, would anybody be willing to help post or give a detailed instruction sheet on how to post the pics as this project begins. Thanks in advance to all. :chevy

427Hotrod

First off anything with an 8-71 is just cool! I've always liked the look and enjoyed the driveability of them on the street. Talk about instant power.

I have a buddy that has a 502 with one in a '55 Chevy. The car weighs like 4300+ lbs. A/C, PS. PW, cruise, Gear vendors OD etc etc and is a beautiful Pro Street type ride. But he literally drives it everywhere. He did the whole Power Tour this year. It runs somewhere in the 11's which is pretty decent considering it's mild nature and hefty weight!

One thing that always concerns me though. Supercharged/turbo cars seem to put up unreal RWHP numbers that often don't correlate to real track times/mph. Sometimes you see one all dialed in, but usually they are way off.

What I would love to see is someone to get BDS or someone to really work with you to develop a strong "functional" setup. It's a shame to see what HAS to be unreal potential not live up to it's ability. You never see Roots blowers in gasoline racing anymore. You see lots of centrifugal and turbos, but no Roots. I'm sure a Roots can be made to make the HP, but somehow the heat and efficiency issues have to be addressed. I would think by now one of them would step up to prove they can run with the "big dogs". There used to be that guy in St Louis ...Weckman (?) or something like that. He had a midyear race/street deal that eventually became a blown alcohol deal Kind of a shame it didn't stay on gas. There was a Camaro a few years ago that Oddy built and Hot Rod featured it. Made 900 HP or so and ran high 9's in a pretty portly streetable car. I thought it was pretty cool.

A couple of weeks ago I when I was at the track, there was a race only '55 or so Chevy pickup running. Fully caged, tubbed, big slicks etc. All out race deal, though I'm sure it was pretty heavy too. He was running a race gas only 540 with Dart heads, big solid roller (high .700's lift) and an 8-71 with two Dominators. It sounded good and pulled nice straight wheelies, but was running the same MPH I was which is a pretty good HP indicator. The air was really bad that night but I figured it wouldn't hurt him as bad as me. He said in good air it ran 9.60-9.70's@139-140 mph.

So, I for one would love to see a buildup on one, but do some digging to see what they really need to perform. In theory the blower ought to make unreal power, but reality sometimes translates different. Remember Merlin. It was talked about a lot, but was WAY below the naturally aspirated power several of us were making on pump gas. It just had some bad parts combos and tuning issues I hope. The numbers quoted for it were way exaggerated from what it really made. If you read the posts, the RWHP often came to you through a "correction filter" that told you what crank Hp would be. One post started out listing RWTQ that was multiplied to be "crank TQ" that quickly became RWHP during a couple of misquotes and he never corrected them. You know the drill, once a story gets told a few times it takes on a new life. I was amazed watching the "following"!

Norval definitely has proven he knows how to make one live on the street. I'd run ideas by him and see what he thinks.


Good luck!


JIM

noelga

Glad to see your joining the club.
There can never be to many blown bb corvettes

Light84vette

How much respectable power and boost can be attained from a 8-71 huffing down a 509 merlin? :confused:

Beach Dude

OK, this is the plan, after Thanksgiving weekend, I plan to order the supercharger from Dyers. I have spoken to Bill Dyer, very helpful individual, the goal is to still run on 93 octane, remember I said street car. Will run better gas at the strip, plan on running very moderate boost, only around 6 pounds, motor is forged bottom end with 9.1 compression, a helpful advantage is this car only weighs approx 2600 pounds. a realistic goal I think is 750 crank horse with very decent street manners. If you cant drive it, why have it. IMHO. :flag

427Hotrod

I think that is awful conservative HP goals for a blown 509. For sure it can make that and live forever. That's pretty much how boat guys do it. They make mild HP at low rpm and just run forever. So depending on how mild you want it, you will easily get there. The TQ curve of something like that wil be unreal.

A good pump gas 509 can make 700+ hp without too much work, so I would realistically expect HP numbers more up in the 850-900 range in a streetable tune.

But just as I said about that buddy of mine....you can have a super streetable reliable almost zero maintenance blower motor. I'd use a solid flat tappet cam and just run forever. Don't be scared to use large heads, the blower will take care of any bottom end issues. With larger heads you can make more power with lower boost.

And I can't even imagine how much fun you're going to have with a 2600lb car!!


JIM

Beach Dude

Hey Jim, I appreciate the comments, I would rather guess conservative than be over optomistic. The general rule per dyers is 1.5 horse per cubic inch I believe. As far as Heads, I am using Merlin heads 310cc. The cam is a solid cam, but not ideal for the blower, but will live. I plan on changing the cam and the pistons down the road a little ways. If any of you guys are in the southeast, their is a great show/swap meet at Daytona speedway during Thanksgiving weekend. I would like to meet any corvtte forum members. Drop me a e-mail. Thanks :seeya

Light84vette

:eek: Holy, how did you make your car weigh that much compared to a stock corvette? Also what kind of transmission will you have to recieve that enormous powe?

Beach Dude

Hi light 84, It's a tube frame chassis car. Mustang II type frt susp with steering rack, Transmission is a turbo 400, rear end is a 9" Ford. Due to the car's light weight and being a automatic, I don't anticipate major drivetrain stress, however, I could be wrong. Been there before.

427Hotrod

Can't make it this year, but I went to that Swap Meet at Daytona a few years ago. It was fantastic!

Plus we went to Garlits' place ( he was there so we got to BS a little) and had a great time hanging out at the beach.

C'mon..if you can afford a blower, you can swing a new flat tappet cam right? Waht's wrong with the pistons you have?

1.5 per cube ought to be pretty easy to get with boost. Not even breathing hard. Have you already got those heads?

JIM

Beach Dude

Hey Jim, sorry you can't make the show at Daytona. pistons are 9.1 forged, but are not blower pistons, this is the reason I am going with the lower boost level to keep the cylinder preassure down. I already have the Merlin heads, otherwise I would be looking real hard at the afr's. I thought the hard part was done by getting the money and the wife's consent. :cheers:

norvalwilhelm

Beach Dude. I have been running a 8-71 on my 460 bigblock for 3 years. I run it 15% overdrive and it makes about 12 pound of boost. I run 2 850 double pumpers that have been extensively reworked. I run them very lean but have the power valves referenced off the intake. I run no springs on the power valves so vacuum keeps them closed and boost blows them open. I run 15-1 fuel ratio under light cruising and 13-1 and time the boost starts.
Under normal acceleration it puts out 5 pounds, push it a little harder and it easily pushes 10, step on it a little more and you can no longe look at the gage. I get 14.4 mpg around town with a little highway driving , it never overheats, fouls plugs or loads up.
I ran a nitrous motor before with heads that were too big for the street, Once I got the blower these same heads worked from idle on up. It will produce maximum boost right off idle. I also ran a 700R and blew 3 of them in one summer and 4 torque converters. I then ran a Tremec TKO and even in 3rd gear just leaning on it would cause the 305 radials to let loose.
I would not go back to normal aspirated after being spoiled by the blower. The visual effect causes people to pull over and let you by and even in 5th lugged down to 1200 rpm it will pull away smoothly.
I run 43 degrees of advance but have a Boost timing computer to pull timing out of the motor, 2 degrees per pound of boost.
I started with 8-1 compression and with 12 pounds it goes to 14.5 but seems fine on 94 octane.
I made a custom lower pulley to space the accessories in front of the blower pulley so the power steering and alternator could be mounted low and in front of the motor. Stock setup mounts them high and to the side.
Good luck and if I can help just email me.
Double click to enlarge

Beach Dude

Hi Norval, thanks for the response, I do have a couple of questions, I have been looking at Dyers and BDS. both 8-71's
Dyers runs the Holley Carbs, does not demand the double keyway on the crank.
South State Speed shop deals with BDS, uses edelbrock carbs, demands the double keyway.

Any recommendations? both companies have been around for quite some time. I do not want to teardown the engine at this time, but I don't understand why one is very adamant about the double keyway and the other is not? Thanks for any suggestions. :cool:

norvalwilhelm

I don't know about the double keyway but it did it to be safe. It is not a big deal for a machine shop. I did my own by setting the crank on the mill and cut a second keyway not quite 180 degrees from the original.
I cut it offset to prevent me from ever putting the damper on wrong 180 degrees out.
BDS is a good product, I don't know Dyers. I also O ringed the block for safety which again is not hard, I did it myself but any shop would do it for about $150 or buy the tool from Summit and do it yourself. I used .40 stainless wire.
I used a .040 copper head gasket.
For carbs I only use Holley because I really know them and know how to make them work. I'm sure other carbs are just as good if not better but I could tear one apart, drill new holes, plug others and no what I am doing.
My 2 850 double pumpers run lean, get great gas mileage, never load up and yet under boost richen right up at the proper time.
I am not a holley fan but I know them and can make them work.
I know holley also sells carbs just for blower applications and has the blower reference power valves.
Good luck and let me know if you have other questions

mike 1985

my brother has a 3450 lB 68 camaro that's been blown with Dyers superchargers for 15 years. This car has taken on many different set ups, but all blown.

We have had nothing but good luck with the dyers blowers and people.

it's a 468 with a 6-71 GM ZL-1 alum heads ( for sale) turbo 400 11" coan converter and 12 bolt with 3.73 gears.

the quickest it's been is 9.66@148 with a 28X9' slick. This was 12 lbs of boost, 264-274@.050 cam 714 lift on 110 LSA ( not really a blower cam) and a 125 shot of nos.

the current config is 6 lbs of boost, comp cam hyd flat tappet nitrous cam 240-253 575-595-113 LSA. Drove it to the track and ran 10.89 on 93 premium. 2004 will be AFR heads the same cam and 12 lbs of boost with a 250 shot. The motor will run on 93 and use race gas at the track. He says it'll go 8's.

we do all this with 2 stock 750 vac secondaries.

e-mail me if you want his e-mail address.

Light84vette

:eek: :cool: WOW, thats way too cool. Love the way you have some guages under the cowl. :yesnod: How do you get that legal and smogged? :confused: Also do you intercool the intake charge or do the carbs cool it down when the gasoline hits the air? And is it 8-71inches of displacement every rotation of the crank or is that 8-71 for every 2 rotations? :confused:

norvalwilhelm

I haven't had a problem with the police in the 3 years I have been driving it in this form. I am told that as long as you can see both fenders you are fine. As for smog it is past needing a smog test. Older cars are exempt/
I do not intercool the air, it is very difficult with a blower. The 871 is designed for an 8 cylinder engine each with 71 cubic inches so the blower is designed for a 568 cubic inch motor.
I run it 15% overdiver and 12 pounds of boost. Driving it overdriven like it is gives you 5 pounds under light throttle comming off the lights and a quick 9 pounds with just a little more throttle.
I have never seen 12 pounds, lots of 9 and 10 but once the throttle is down you do NOT look at any gage, not even the tac. Things happen too quickly. :)

Light84vette

:crazy: Damn, from the pictures it looks like you have atleast 26+inch rear fatt tires, are those 28inchers? Do you have a solid axel in there? :confused:

I'd love to put a blower on my vette, but that would mean I would have to cut a hole in the clamshell hood and a replacement hood is pretty expensive.

Anyway thats one baddazz corvette :yesnod: :seeya

Beach Dude

Norval, Mike, thanks for the advise, I will be e-mailing both of you guys as this gets closer. My biggest questions at the moment are Holley or Edelbrock carbs. Norval, I know you like the Holley's because of your familarity with them. Also what percent of overdrive/underdrive to go with. Remember, this is on a street car with 93 octane, that is the best we have in my area from gas stations without going to some airport or sprecialty shop shop that sells race fuel. Thanks guys. :steering:

mike 1985

We use off the shelf holley vac sec carbs And put in 50 cc accelerator pumps. You would need a couple of 850's for your app.

As far as boost we run 6 LBS for 93 premium with iron heads and 36 deg total timing. If you can get the car to run 160-170 deg you can probably go to 8 with a little less timing. Your cam specs play a part in the total boost anfd octane requirement. Mainly the LSA.