Chevy 366 hop up

[the_experience03]

Might I suggest a supercharger over a turbo? For your intended application it will be much better as the power will come on right away on the bottom end. I know you said you aren't worried about turbo lag since buses don't accelerate fast enough to care, but I think you'd be much happier with the low end power of a roots type supercharger. On top of that they tend to make more reliable or perhaps predictable power on the lower end of the boost spectrum. I'm all about using wasted heat energy (because it's heat, not exhaust velocity that turns a turbo...you wouldn't believe HOW many times I've had that argument with people), but each type of forced induction, whether it be turbo, roots supercharger, centrifugal supercharger, etc has its own special place in life. On top of that I think it might be less work to install and will be a good excuse to get that higher flowing intake

[hoser]

Originally Posted by the_experience03

Might I suggest a supercharger over a turbo? For your intended application it will be much better as the power will come on right away on the bottom end. I know you said you aren't worried about turbo lag since buses don't accelerate fast enough to care, but I think you'd be much happier with the low end power of a roots type supercharger. On top of that they tend to make more reliable or perhaps predictable power on the lower end of the boost spectrum. I'm all about using wasted heat energy (because it's heat, not exhaust velocity that turns a turbo...you wouldn't believe HOW many times I've had that argument with people), but each type of forced induction, whether it be turbo, roots supercharger, centrifugal supercharger, etc has its own special place in life. On top of that I think it might be less work to install and will be a good excuse to get that higher flowing intake

The only reason why I thought turbo was it would be easier to run exhaust tubing than it would be to try and adapt the belt drive for a blower, the belt drives on the bus is nothing like you have seen on a other BB engine or truck engine even the water pump is a special setup/casting then you have the air compressor for the air brakes, it could be done but I see alot of money spent on all new pulleys and bunch of time making new brackets, if their was a bolt on kit I would be all over it

[wtd]

Next argumentative topic: How can I hop up my 392 IHC without swapping,

I said, I don't want to swap it.

NO, I'm not swapping it out.

Can't we all just get along?

I don't know anything about that engine but you should really swap that for either a diesel (the one you have isn't a diesel is it?)or a crate of oranges or something ... I remember I had a Caddy once with a crate of oranges in it .. ran like a scalded - well, never mind ....

[the_experience03]

You can spend money on pulleys or you can spend money on a wastegate, new exhuast manifold, etc I think either way forced induction is going to be expensive. How about an oil or ball driven supercharger?

Oh yeah...my bus turns 2600 rpm on the highway so I think a caddy would be fine in there....but that's for another thread, right?

[sportyrick]

366 is a smaller version, smaller valves, smaller combustion chamber, smaller bore, of a 427 tall deck motor. the extra height is used up by the extra piston ring, 4 rings verses 3 on cars, and they also have sodium filled exhaust valve stems to transfer the valve heat into the water jacket (big block chevys have wet valve guides, water directly on them) just like a tractor, the 366 is a small bore long stroke motor for more torque. the engine is de-tuned to make it ultra reliable so you can put you foot in it all day and it won't burn up. A regular car engine will burn up with your foot in it all day at maxium load. sorry boys they never made a production tall deck 454, so you are stuck with a car motor if you use it. A guy I know took a tall deck 427 and put a high lift cam in it to help his X Ryder truck get from point A to B faster and he had trouble beating the valve seats out from the pounding that the high lift cams had at sustained high RPM's. they have low lift cams in them for a reason, longevity. I have both, a 366 in my 2 ton truck and a 427 in my school bus, I love them both. get your exhaust opened up, a good stock Holley and good spark and that's about as good as it gets. any divergence from this shortens the live of your engine. a 366 crank, rods, flywheel, intake, water pump etc will fit in a 427 block and all you will need is the block, pistons and heads to jump up to more torque and HP. every mom and pop shop and farmer has worked on one and parts are everywhere (this series has been produced for 50 years), that's why they are still avilable in trucks, they are super reliable and have a reputation for such. this is one of the best-toughest gas engines ever produced. they even tried to put one in an airplane but it just wouldn't hold up to 90% power 100% of the time (remember you let off the throttle going down a hill and at stop lights) ya diesels have more power but the expense is 4 times a gas engine, do the math, by the time you put all those batteries, glow plugs, filters and such in one you lose all the price savings you gain from the xtra fuel milage, not even talking about rebuilds, I can rebuild that 427 on the side of the road for a grand, a major on a diesel is going to cost at least 5 grand and that's if you do it yourself, 12 grand at a shop. A service call on a diesel is $200, a little old gas engine is $35. these engines will go at least 200,000 I have even seen one in a ford truck (that's right, this guy had the right idea, a ford 700 commercial wrecker with a crate 427 Chevy in it) with 300,000 and all he ever did to it was put valve cover gaskets on it. As soon as Hillary Clinton becomes president she will lower the speed limit to 55 and you will be right there with the big boys anyway. You've got a good motor in your bus, just do a little to enhance it and it will last the life of that bus and not cost you an arm/leg to keep running.
Sporty Rick

[hoser]

Thanks sportyrick that is the kinda info I was looking for, so I should try to improve on the breathing a little, I know their is plent of improvements to be made to the entire intake tract so I will be doing a dual inlet mod to the air filter to supply a little more air than the stock offers, it already has the factory headers that flow into a huge muffler that has a huge single discharge then runs to the back to exit by the rear bumper.

What are your thoughts on the mega squirt?

What about adding a turbo to over come the restrictive intake system (air filter to cylinder tract) run it at low boost like 1-2 PSI?

Thanks agian.

[the_experience03]

Again...I have to say how cool that megasquirt system looks. If you can get it working you'll be my hero

Are you sure you have real headers or are they just the "ram's horn" manifolds that chevy used? Don't get me wrong...the ram's horn design is one of the best stock manifolds you're going to find but it still is no true header. True headers have equal length tubes so the volume in each primary tube is the same. On top of that, they try and make sure the exhaust moves at the same velocity. What this does is create small pulses of pressure inside the tube which will lower the pressure on the backside of the exhaust valve helping to scavenge the gases better for higher flow and cooler temps at the valve. Tri-Y (4-2-1) headers take this idea even further by using pulses from cylinders out of sequence to each other in the firing order to scavenge gases from each other. Tri-Y's give a huge torque boost down low where you need it making them very popular in offroad vehicles atleast.

As for the turbo overcoming the intake restrictions...Forced induction is meant to overcome volumetric inefficiencies so in a way it would work. However, your intake restrictions are going to create a lot of turbulence which will slow the intake charge down and inhibit high volumetric efficiencies. The closer to laminar flow you can get, the better. I think a turbo might help overcome the problems on the intake end, but if you're going to boost 1-2 psi, you might as well go to 5 psi. Most stock engines can take 5 psi safely, especially one like yours with forged internals already. Remember...forged parts are what they swap into race engines to help them hold up. The megasquirt looks cool because the literature says it can handle 21 psi of boost

[captainkf]

Hey Hoser. Keep us posted with what you end up doing. I also have a 366 that had a ground up re-build after I bought it. So I am very interested in what you find works.

A couple of questions.
1- Could the exhuast be run through two mufflers and then run out the sides in front of the back tires? I was thinking the shorter run would help it breath better. Or is it even worth it?

2- What kind of carb fit's this engine and does anyone have a good one kicking around that's acting like a paper weight? I am switching to dual fuel system (propane and gas).


Thanks a bunch all. -Richard

[the_experience03]

That shortere exhaust run might help a little as bends certainly add to head loss, but I don't think it's anything the seat of the pants dyno would feel.

As for carbs....I'm still a strong supporter of the Predator carb as a replacement if you choose to drift from factory. They will supply the right CFM for just about any engine because they are more of a metering block than a carb. On top of that, the throttle response is phenominal.

[hoser]

the_experience03 they are true tube headers I will get some pics and send if you want to see them,these are not ram horns I have them on my 72 GMC so know what your talking about,
these are like the shorty headers you I am sure have seen, about half way down the fram rails they have the collector its not down at the oil pan level like most after market headers are they dump into 2" or greater" tubing and run back as duals to the inlet side of the muffler that is about 3' long and 12" in diameter the exit on the muffler looks like 4" tubing that runs to the bumper, the tubing mandrel bent so no volume losses on the trip back I doubt this is a restrictive system for the 366 given all the data I have been given on all its intake restrictions, I have seen plenty of factory exhaust systems and how restrictive they are by looking at this one I don't get that feeling just looking at it I think any motor head would agree its not your normal restrictive factory exhaust system how ever its not headers 1' of pipe and a straight through muffler either.



I have no plans to change or upgrade the exhaust system until it needs replaced unless someone can prove their are significant gains (50 ft lbs torque) I have replaced the exhaust on many of my other cars and trucks over the years with performance "better flowing" systems and the only gains I seen or felt including MPG was the less weight in my wallet, these "performance systems" might enhance something when included with other major mods but IMO offer NO bang for the buck.

Think I like about the mega squirt is the option to control the ignition I have to do some reading but think you could rig up a knock sensor and advance the timing for a longer burn (more power) until you got hits off the knock sensor then back it off again, on my trip with the 366 I never had any sounds of deto even when running 85 octane at 5000' on the same trip last year in my motor home (350 engine) I had a little deto but it was real sensitive to deto from day one.

On the boost thing I only want enough to help me up the tall hills and in the strong head winds I have seen a dial a boost setup where you can dial the boost from the drivers seat, not sure how it works but it would be nice to dial it up to say 5 psi like you indicate for the mountains and them long 5% 7 mile long grades then dial it back to 1psi for the down hill.

captainkf
Yes I think you could have it exit out the sides and I would like to do that has anybody else done this and not had any problems with exhaust gases getting in the cabin, the gains from the shorter exhaust system I am looking for in this type of mod would be from the weight reduction and the extra space under the bus no performance gains would be expected.

My current carb is a Holley something square bore I am not sure of the size but it seems to work well except for the jetting at higher elevations I want to cure this with a mega squirt and let the EFI lean out the mixture as required.

Thanks again guys for the input I will update as I make changes I now realize the only info I am likely to find on the 366 is maintenance and repair not any hop up or power enhancement experiences.


Anybody know the advertised HP and torque numbers for the 366 I know it dont really matter since I know I need more just wanted to know

[the_experience03]

The real headers are cool. Are they stock or did someone swap them on as best as you can tell?

The most common turbo control I've seen that acts the way you're talking about is simply a manual wastegate. All a wastegate does is bypass the turbo after a set amount of boost has been reached. I'm sure there is a setup, either electrical or mechanical, that you could find. My first experience with them was in a Cessna 210T that had an additional control besides mixture, throttle, and prop speed (angle really.....). They must be reliable as the FAA seems to have an issue with anything even remotely unreliable being in the air. I guess this is why there is such a good supply of low hours lycomings and continentals out there for air boat enthusiasts.

The knock sensor thing would be cool with the megasquirt. If your 366 has HEI (and it probably does), the ignition mods available are just about limitless and it would appear from what I've read that the megasquirt is well suited to this system. Just out of curiousity, where did you fine 85 octane at an elevation of 5000 feet? The only place I have seen it is in the "low" areas of Montana and it scared me a little. My little 22re in my truck knocks enough as it is...I don't need 85 octane with 9.6:1 compression, aluminum head or not

A cool aspect of the megasquirt that I see is that you could tailor the system to run on E85. The only real fuel system mods required are running alcohol resistant fuel lines and replacing any rubber parts that might be affected. Personally I'd just change the fuel lines and see what happens. With E85's 103-106ish octane, you could really run some mean advance. I think that might get you some more power. Sure it doesn't get the same mileage as dino fuel, but last time I calculated it out with our local pump prices, you could lose somewhere around 35% of your fuel economy and break even. I haven't done the calculation in a while.

The system could truly be dual fuel even. The megasquirt seems to have provisions to adjust just as the new cars do for the fuel. An additional sensor is installed that simply calculates the amount of oxygen in the fuel with pure ethyl alcohol having much greater amounts of oxygen than gasoline. If you set a max and a min timing and fuel map, I would imagine that computer is capable of interpolating from there for various contents. That combined with the various other sensors like the knock sensor could really help wake things up. Just an idea though....certainly there's work involved with it.

[SamW]

I too have a 366 in my 1985 Blue Bird Bus. So far I have only driven it about 1 mile. It had sat for about a year with out running. After about an hour of TLC it was idling on its own. I never got the bus over 30 MPH on the drive home (not from lack of trying).

I ordered a sevice manual from GMC. Hopefully, it will have the needed specs on cylinder compression and other various things. When it arrives (should be here by 11-24-06) I'll be happy to share anything the book might have in it. (That's if it is legal to share info like that)?

[Gyva]

Find anything that worked for your desired power gain?



Mike....

[pervy2u]

There's been some good advise on gas engines. Although I am a moron with diesel engines I do have a little experience with gassers.
From a basic factory setup the easiest way to increase torque and add a little horsepower is to start with how it breathes. If you can't get air in and out you are limiting the capacity of the engine and for the most part factory setups just don't breate well.
If your gasser is naturally assperated you might start with the air cleaner. The more surface area the more air is available. You may also install a spacer of at least 1" thickness under your carb or throttle body to help increase the effectiveness of the intake manifold.
Keep in mind that your engine can only take in as much fresh air as it can force out the tailpipe. Air in equal air out and vise versa. Now that the engine is capable of taking in more air you can dress the exhaust manifolds ports with a dremel tool to get rid of the factory mold flashings that create turbulance and drag. Better yet is a set of headers but dressing the factory manifolds will help a ton.
It's a long long long way to the back of a bus and any obstruction in the tailpipe is magnified by it's length. I'm no physics expert but I do know resistance is compounded as length increases. A muffler change may be in order also. It's often difficult to tell if a muffler is restricted but if there are any doubts, like it feels heavier than you think it should, change it out just to be sure.
I raced stock cars as a younger man. When building street stocks about the only engine mods we were allowed to do were external. It is amazing what cleaning up the airways can do to a stock engine.

Larry

[Gyva]

I looked everywhere last night for 366 specs with no luck. I wanted to know what size cams these things came with from the factory. My machinest told me a good rule of thumb is, is with stock head springs you can run a cam that has about a 1/2 inch of lift or .500 or so... my 350 gas engins in my truck run a .458 lift cam with stock head springs and no problems at all and tons of power in the low RPM range ( I run a 1970 GMC Jimmy with 40X17 mud tires) Sooooo I would think if GM put a weenie cam in these 366's a decent cam might get some more tourqe outta them.. but I cant find any cam specs!!!! ha ha.. I'll keep looking....

Mike...

[pervy2u]

In years past GM produced a "Camper Special" version of their pickups. There were various upgrades throught the vehicles that resulted in this special package designation, but the engines were basically the same with the exception of the cam. Parts houses carried the "camper special" cams for those wanting to do their own conversions. Basically the cam resulted in a shift in the power band to a lower RPM but it was a trade off that left the top end performance lacking. However, the cam worked great for guys racing 1/2 mile oval dirt tracks!

[Gyva]

dang! I just went to my local GM dealer hoping they had books or could make a phone call and get the 366 specs.. NO LUCK!!!! Its a quest now... all they did was refer me to the GM website which I spent several hours at last night also with no luck... I'm still on it...


SO easy to pawn off work now a days by saying "ummm try the website" what would they have done if I brought them my bus to work on, winged it??? scary.... always do yer own work......



Mike...

[the_experience03]

My big block chevy guy recommends a Comp Cams 270 Magnum for this application. It's more cam than you'll ever need for any other mods you do, but shouldn't sacrifice any driveability. He said that is about the best you can do short of swapping heads to get better ports. The bore is too small to run a valve of any real size. I personally have no experience with this cam, but it comes from a guy building a 475ci alky BBC for an S-10 mud racer.

He knows his stuff...his current truck is a fullsize half ton chevy with a 402, TH-400, and get this....Ford NP205. He runs a 9 inch rear on a shackle flipped leaf spring set up for now with a C-10 trailing arm setup in the works. Thge front end is a high pinion Dana 44 suspended with extended Ford radius arms and coil springs. Needless to say I trust his knowledge base.

Here's a link to his work if you're curious....
http://nwmudrace.proboards42.com/ind...ead=1145935388

[Gyva]

Found these specs for 71-76's out of Chiltons

366 Specs:

Plug Gap: .035
Point Gap: .019
Timing: 8 BTDC
Idle: 500 with AT 600
Fuel Pressure: 5 - 6.5
Bore Stroke: 3.937X3.76
HP: 200@4000
Torque: 300@2800 RPM
Compression Ratio: 8.0 71 - 74 ---- 8.0:1 75 - 78
Normal oil pressure: 40-55
Cam Lift: .234

Torque Specs:
Head bolts: 80
Rod Bearing: 55
Main Bearing: 100
Crankshaft Balancer : 85
Flywheel to Cranshaft: 60
Intake Bolts: 30
Exhaust Bolts: 20

Given this knowledge I'll be changing out my cam and lifters on my bus the .234 has much much room for improvment. During my search I found a recomendation which was the Howards RV Cam #120021 which reads,

Lift: .476"/.502" Duration @ .050": 204/214 Lobe Center: 112 Exceptional low end torque. Good in PUs, 4X4s and RVs

Found at http://www.competitionproducts.com/prod ... p?dept=320 for $62.00

I'll probably call a few places but this one looks like worlds of improvment over the stock .234 Thats all I could find guys... hopefully this helps someone.


Mike...

[pervy2u]

Good luck on the cam change! I'm sure there's one out there somewhere that will fit the bill and give you what you are looking for in performance.
I hope you have enough clearance to go from .234 lift to .476 lift. Those valves would be shoved over twice as deep, almost an extra 1/4", into the combustion chamber!