502vett

Hey guys, sorry for this long post/questions. Hopefully someone has time to read my novel... I just want to make sure I get all the info across...

SO: Can I put a small (low boost 3-5 lbs) Weiand 177 series supercharger on a GM 502 Big Block crate engine (9.6:1 comp)? It is for street use only - no strip use...

Background: I "completed" my 1980 Vette 502 B/B project a few months ago. I got the thing dynoed and I am losing 150 hp (I got 354 hp and 374 TQ to the wheels). I was a bit disappointed with this, but it was to be expected with a 700R4 automatic tranni. 30% loss is about right with this slush bucket set up! Ok, now I would like a bit more pick up and power - not crazy more - but I would like about 75-100 more hp and more TQ to the wheels. A fair amount to ask, but not ridiculous...

I realize there are other methods, nitrous, cam swaps ect, but I want to make a smaller roots-style blower work. In particular, a weiand 177. I love the look of it - protruding from the hood - aggressive and classic - I don't mind at all cutting my hood out. I would like to stay away from a Procharger style or turbo. Too much plumbing, customization - and pricey. Roots or nothing. Hopefully I can make it work with pump gas...

So a few issues.... The biggest issue, is my current 9.6:1 static compression. I am reading that I should not even consider this blower idea with this high of a comp ratio. I've called weiand and they (of course trying to sell me one) said I'd be ok to run this on my application (with high octane pump gas - 93 oct), but at a 3-5 pound boost max. only. That's cool with me, I'm not looking for extremes here... But - other online research is telling me different - that I would have to run on race gas (which I don't want to).

I'm sure other guys have done this!? Anyone?

So I am a bit confused.

My current set up (fyi):

Engine:
GM 502 Big Block crate engine (nothing modded) which has:
502 HP @ 5200 RPM
567 ft/lbs TQ @ 4200 RPM (Max Recommended RPM: 5800)
Compression Ratio: 9.6:1
Cast Iron 4-Bolt Main Block
1053 Forged Steel Crankshaft
Forged Aluminum Pistons
4340 Forged Steel Shot-Peened Connecting Rods with 7/16" Bolts
Aluminum Oval Port 110cc Cylinder Heads (2.25" Int/1.88" Exh valves)
Hydraulic Roller Cam (Lift: .527" Int/.544" Exh, Duration @ .050": 224° Int/234° Exh, 110 degrees lobe centerline)
1.7 Ratio Rocker Arms
Aluminum Dual Plane Intake Manifold
HEI Distributor and Spark Plug Wires
8" High-RPM Torsional Damper

Other:
Holley 950 carb
3200 stall TCI TQ converter
700R4 tranni (rebuilt a bit stronger - to handle this engine's higher stock power)
Stock diff with 3.07 rear end (I plan to beef this up (iron diff) and change the ratio to 3.73 - next on the list)
running elec. fuel pump (holley blue) at 6 psi with a return-line regulator
duel elec. puller fans
New dewitt's aluminum rad
Hooker headers and side pipes (with max-flow inserts)

My questions:

1. I am told that based on my engine (see above specs) and current dynoed rwhp max of 354 that 3-5 pounds of boost will get me 70 to 100 extra rear wheel hp - do you think this is approximately correct?

2. "No cam change required"... I'm told both by "Lunati" and "Comp cams" that my current cam (see specs above, 110 deg lobe) is ok with this little 3-5 pound of boost. They say I will not have problems, (since my engine having a low rpm max, i.e. not reving super high) and that most of my driving is under 4500 rpm, and also that I'm looking for more lower-end increases in TQ and "off-the-line" kick... Do you guys oppose? Can I roll with no problems and no boost loss with my current cam?

3. I live in Calgary, Alberta, Canada - about 3550 ft above seal level. I accounted for this higher elevation in (Weiand's Effective compression ratio formula) calculation and figured at the 5 pounds max boost, my new compression ratio wound be 12.09.... ( 3 pounds gives me a ratio of 10.84:1). Weiand says anything around 12 or above will req. race gas - or I'll have detonating problems! I don't want that! Will I be ok with high oct. - 93 - pump gas with this borderline 12.09 compression, or would it be feasible and wise to incorporate one or more of these strategies: An intercooler, A boost retard device or Mix a portion of race gas in my pump gas????

4. Intercooler: Do they make an intercooler that sits between the carb and blower, for a weiand 177? I cannot find any? would this help me stay away from any detonation problems?

5. Retarder device: If I used a boost retarder device, first of all, would this be effective against detonation, and would I loose a big chunk of my gain from the blower?

6. Race gas mix: If I do have to use race gas - since I'm boarder line (i.e. 12.09 compression max.), can I go a cheaper route and mix a ratio of race fuel and pump fuel? does anyone know of a good ratio (i.e. 75% 93 pump-gas octane and 25% 110 octane race gas)?

Finally,

7. I know I need to "manifold reference Power valve" my existing Holley 950 carb, but should I change my current Holley blue elec fuel pump to a higher output one (like holley black)? Should I increase the fuel pressure (current 6 psi)?


Thanks in advance guys, again sorry for the novel! Hope someone has time to read this! HA!

mint79

read your post real quick,what caught my eye was the 177 Weiand.
I have this blower on my 454 in my boat. Mercruiser sold it as the 525sc. it has a 1050 dominator for carb. Has been absolutely troublefree.
They lowered the comp. ratio to 7.25:1 I have run this engine at 5400rpm for perhaps 5-7 minutes. no issues. With the 5lb. pulley overdrive is 2:1. at 5400 i am spinning that blower 10800rpm.Sounds like a bag full of bees.Intercooler is available from nordscog marine, but is is set up to use lake water for cooling-any questions-just ask.

MotorHead

MY personal opinion on those type of blowers you don't want to know. I would sink some money into a good set of heads and matching cam and you will be much further ahead and won't have to try and sell that blower in year or two.

FRSTR90

I am kind of with motorhead on this one.. I would first ditch the max flows, and install a set of the JCL Baffles. Then I would look into a Performer RPM air gap and cam change from comp cams, lunati, and even crane (if they still sell cams).

IMHO - If you are going to add a blower to your ZZ502 make it worth your while. Find yourself a nice set of AFR's with atleast 119cc chamber, and you could probably run 6-8lbs of boost.

78Vette-SA

I don't ussually chime in on these but this time I am curious. First off, why do you concede to losing 30% with a 700R4. I've never seen that before. I've seen 18-20% tops with the R4. To me you should have been bringing home about 400hp and 454tq at the wheels which is close to what you want out of the box.

Have you started with the basics like carb and timing tuning (valve adjustment) with what you have and perhaps another dyno before you start droping thousands on it literally and figuratively? And your talking to someone who likes blowers but I also believe in back to basics first.

I run 7:1 on a 9:5 compression stock bottom end motor (not-forged) LS6 motor with a 228/232-588/592-114lsa cam and it purrs. Will it blow some day, maybe, but it is totally streetable and I don't put my foot into it that much although I am going to do some 1/4 mile runs with it on Oct 9th with some C1/2 Forum members for fun. But, I haven't dyno'd it because numbers don't mean a lot to me in this particurlar case because I built it to drive. But if you are going for numbers, it sounds like you have a decent motor there and I would go back to basics first before throwing more money at it. But that's me.

My .02.

69ttop502

350-370 rwhp is normal for the zz502. I know of 3 of them that have been chassis dynoed in various combinations. Mine, with a Muncie did 350 rwhp. I then redid the motor with a solid flat tappet, AFR heads and so on, and I now have 614 crank hp. Haven't chassis dynoed but I am sure I have at least 100 more at the tires. I agree that this would be a better way to go.

I would bet though that your actual measured compression ratio is well under 9.6 to one.

GDaina

A simple cam change will do you a world of good and put you way above the 400 HP at the wheels....Comp Cams solid street roller, 288AR will idle @850 rpm all day long, give you 14" of vacuum and tremendous power throughout the RPM range. If you want more power the 305AR Street Roller will do that but give you a more radical idle...

I ran the 288R in my 68 and couldn't ask for a better streetable cam. The 288 still would be in my 68 if two rollers hadn't disintegrated, now I put in the 305. Haven't take the 68 out yet so can't comment on the streetability, but this week I will be done.

502vett

These are great responses and suggestions, thank you guys. I appreciate you taking the time to read this.

78Vette-SA, I agree. I thought the same way! This is why I was so disappointed when I got that lower 354 rwhp #. Also, when driving, it feels decent powerful, but just not that "kick" feeling, that I expected... I realize I can also mess with the diff ratio, but I'll save that for later... I even had it dynoed twice (I know, waste of $).
The first time I had a 800 edlebrock carb, tuned and re-tuned, tried different jets ect. Max I got was 354 rwhp. I was then told to get a bigger cfm carb, so I went out and bought a Holley 950. Slapped that on (even messed with it's internals a bit) and only improved by 10 rwhp (364). Besides opening up the motor and getting down to the basics, I think this (~350-370) is all the 502 (behind the 700r4 slush bucket) makes (stock).

I really like the look of a blower. I really want to make one work. Maybe I am naively thinking that I could do minimal work and just "bolt one on and go", and not have to pull my engine and take it apart! That's just laziness. I will not rule out going back to the basics and digging deeper.

My 2 options so far:

1. Start with the basics. Learn to walk before I learn to run.
Crack open the engine and change out the Cam for a more aggressive one. My only issue with this is drivability. I want the hp gain, but don't want to stall at red light (i.e. poor drivability). Along with the cam, I could also change the Heads for something more "giving" - I'll have to research this as well - and am open to suggestions! Sounds like AFR's

2. F-it, throw on a blower - spend the $ once, up-front and be happy with the look and huge potential increase!?
So, roll with a weinand 177 supercharger, but first reduce my (static) engine compression down from 9.6:1 - if that's what it really measures, might be lower, like 69ttop502 mentioned (hopefully) - by throwing on larger chamber heads (like 119cc by AFR as FRSTR90 mentioned). I wonder, by how much will my static compression go down if I go from my current "Aluminum Oval Port 110cc Cylinder Heads" to 119cc AFR heads???????????? Will it go down to the suggested Weiand max of 8.5:1 static compression???

Correct me if I'm wrong, but from what I'm reading in other posts, it sounds like stealing (lowering) static compression in order to run higher boost will give me much better performance/power? I might be out to lunch, but by upping the boost to 6-8 lbs, I might even be able to achieve a 100-150 rwp gain??? Which would be way more than a cam and heads, yes/no???

Also, sounds like doing this 9lowering my current static compression), I wouldn't have buy an intercooler and/or boost retarder to deal with potential detonation problems!?

ajrothm

I think the 30% loss is pretty accurate from crank HP to rear wheel hp.....Remember its not just the tranny sapping power, its the IRS, the exhaust, the mechanical fan, accessories, air cleaner etc....I think his HP level is pretty dead on for what he has.

As for the blower, in my opinion..(my .0000002) I don't think its a bad idea at all to slap a blower on it....Here is my reasoning..

1) The ZZ502 bottom end is pretty damn tough and they run forever.(if you didn't get an oil burner)
2) You will have stock like driveability with plenty of vacuum, basically a stock big block under the hood.
3) The monster low to mid range tq this thing is gonna make will work fine with the hwy gears.
4) It looks cool, sounds cool and will be different.

The tech data..
I don't think 9.6-1 compression is too much for pump gas if you have the correct tune and 5psi, thats IF its really 9.6 to start with.

I don't have any experience with Roots style blowers, I do know they make a lot of heat which adds to detonation, but I have done quite a few centrifugal and turbo setups on different stuff, BUT it was primarily on LSx based engines and they have better/more efficient chambers, better engine management, knock sensors etc....but we often throw blowers on Z06 vettes, put 10psi through them(although with air to air intercoolers) and they run forever with the correct tune and make 600RWHP. You are not talking anywhere near that kind of pressure with what you are wanting to do.

My theory for you is if you keep the boost at 5lbs at peak RPM(remember it ramps up with RPMs, from 2500 up to 5000 you are only talking about 2-4psi), run an MSD BTM(boost timing management) system to retard timing as the boost builds, go a couple ranges colder on the plugs, get the carb jetted right(you will need a double pumper, vac secs won't work right with a blower I don't think) and always run good 93 octane from good stations, you would be fine. I would definetly penny up for a LM2 wideband datalogger so you can watch the AFR from time to time, keep it in the mid to upper 11s, I think it would live a long happy existance...

As for the gains, 5 psi at peak would likely get you 75-100 CRANK hp....so you could figure another 50-75 rwhp....Is it worth it for the loot its gonna cost you? Probably not...but it would be different and driveable as can be.....It would probably be cheaper to do a head and cam swap and make the same HP gains or more, BUT you would have to strip your new motor down again...

This could go either way....me, I would probably do the head/cam kit, but if your heart is set on the blower, I would say go for it.... Keep doing research on it and get some different opinions, but I think it could work.

Billysvette

Im not going to push a blower, i run one,and will not run without one,all my vehicles have blowers.Motorhead im a shamed of you apparently you dont know about blowers or you would not crack on them.75 to 100 hp just bolting one on a regular stock engine.Theres alot more to it but where you going to get that kinda hp for little over $1000.I didnot dyno my engine but i would say i will beat most big blocks out there,that are not blown of course. Motorhead give a blower a try and you will not go back,guarentied Remember at the track its either blown or sprayed

tt 383

I f you have to cut the hood and have shiny thingS stick out why not go for an 8-71 or high helix 6-71 from the blower shop? They will most likely perform better for that size engine. Not sure if the factory gasket would be ideal, maybe someone knows better than me. I, would probably replace with a MLS gasket, and to justify while the heads are off open the chambers, gasket match I/E Runners and bowl blend factory valve job.

ajrothm

+1

I was gonna suggest a 6 or 871 also but figured the cost would be more then he wanted to spend... Much better fit on a big ole 502 though....bunch more power at the same boost level..... BUT I would pull the heads and at least put some thicker head gaskets in there and maybe some chamber work to help bring the compression down some....Could easily make 700 crank hp on a stock 502 with a big blower....Ofcourse this would cost you $3-4k for everything you would need but...It would be super cool...

MotorHead

I think you missed the point, and please don't make assumptions you know what the first three letters spell. I never said I didn't like blowers, I love them I just don't like the Wieand 144 looks mickey mouse to me I know someone who put one on his big block and after a year he took it off, didn't like the looks of it, and he was always trying to get it to run right

He wants a blower put an 8-71 on it or a 14-71 like I put on mine


I am probably one of the biggest supercharger fans there is who else would get close enough to this Top Fuel Funny Car...


To get a hole burnt in his coat by something shot out of the zoomies



And now back to the regularly scheduled event

yellow 72

If you're gunna go through all the work to do a roots blower, do a full grown one They do a whole lot more with a lot less effort...

Rolling Thunder

Get back on the dyno running out of the headers without the sidepipes. That's looks to be your biggest restriction. Solve the obvious then you'll know what you have left to tweak.

tt 383

There was an article in one of the mags about installing an 8-71 on a 454HO and i believe they ended up with 825 on the engine dyno. It was called FrankenRat and was a 6 part series but the parts you want IV and V dont seem to be anywhere on the net? Part 6 referenes that 825 horspower was where they drew the line with the stock longblock. So with the right blower and fuel you can coax alot of power. Do you have a deal for the 177? The 6/8-71 are only 5-600 more.....

GDaina

The problem with the crate 502 is the anemic cam Gm puts in this motor. GM designed and marketed the 502 for boats then the gearheads started to put the 502's in their rides.

bashcraft

Are you talking about the HO or the ZZ? They use different cams.

69ttop502

I think the cams in the hydraulic roller versions of the two motors are the same. Even if they aren't GDaina is correct that the cam is very anemic. My motor fell flat at 5000 rpm. My thinking on going heads and cam for the OP is that a motor that will rev a little is fun, especially in a big block. It also makes it a little more driveable by killing off some of the low end which is still going to be significant with a 502, even with a huge cam. With a ZZ502 short block, I would throw on a set of AFR's, milled a little to get compression up to at least 10 to 1, throw a solid flat or roller in it big enough to make peak power somewhere over 6000 rpm. It will still be docile enough on the sreet but will be fun in the upper rpm range as well and would be very durable as well if done right. My solid flat cam is 258 @ .050 and made peak power at 6100 rpm. I wish I would have gone bigger. It still idles at 850 rpm and is very driveable. With the AFR's and a good cam and intake, you will easily reach your power goals in what should be a very reliable motor.

Bill

bashcraft

HO 502
Lift
510 intake
540 exhaust
Duration @ .050
211 intake
230 exhaust

ZZ 502
Lift
527 intake
544 exhaust
Duration @ .050
224 intake
234 exhaust