Blow through 366T Big Block ?

JavaJeep-INDONESIA · Posted: Fri Jul 29, 2011 2:43 am Post subject: Blow through 366T Big Block ?

Big block Chevs are very rare in Indonesia , I found one in a 1978 C65 Chev which is no longer used at one of the airports I work at (1,300 miles total mileage) and I'm trying to buy the engine and trans (5 speed manual) out of it.

This engine would be perfect for my Jeep J20 pick up project , the Jeep is being built as my workshop truck and will be used to haul a 40 ft long aircraft recovery trailer.

This engine is a 366 tall block (I was hoping 427 or 454) but good enough for what I want , I don't need high speed , rpm , I need lots of torque.

I was wondering how suitable this engine is for turbocharging in a blow through configuration by building an airbox and modifying the holley 4 barrell carb (I've read the other posts here on holley carb mods for blow through) ? Very mild boost 8 to 10 psi .

I have a Garrett TK-0659 aircraft turbo from a Lycoming TVO-435 (Bell 47 heli) aircraft engine , in its original installation this turbo provides approx 8 psi of boost on a 435 cu in engine at 3,200 rpm , I'm not really fussed about a bit of turbo lag . The turbo is a single not split intake.

I want to basically do a junkyard build up on this , keep the engine as stock as possible and add a mild turbo . Would you change the cam or just use the stock cam for turbocharging ?

Thoughts ?

JavaJeep-INDONESIA · Posted: Fri Jul 29, 2011 12:50 pm Post subject:

clay · Posted: Fri Jul 29, 2011 8:57 pm Post subject:

I would leave the stock cam in. It will make more power and torque with a cam swap but I don't know how available aftermarket stuff is or the cost associated with getting it there. Don't get me wrong, it doesn't take a lot of duration to make incredible power so the stock cam won't kill any hope of making power by a long shot. There are numerous engines making over 1000 h.p. (and probably in the 800 ft. lb. range) with no more that the mid 230's duration at 0.050". The low compression ratio will help if you don't intercool it. What kind of fuel do you have access to? I have run into problems with pump gas changing from summer to winter mixes. I'll look for a link to post that has a pretty good writeup on converting a carb to blow through. I've done some sort of different things to mine and I'll help you with anything I can. Glad to see you back around. You always have some interesting stuff to work on - very different and I like that. Clay

JavaJeep-INDONESIA · Posted: Sat Jul 30, 2011 4:15 pm Post subject:

I can buy 95 octane pump gas here , the octane value is real , we've had samples tested in the lab for some Cessna 172s running on auto fuel

A stock 366 with the governor removed should be ok for 5,000 rpm ?

clay · Posted: Sat Jul 30, 2011 5:30 pm Post subject:

That's great on the fuel, at 10 lbs. you shouldn't have any problems without intercooling considering the compression ratio the 366 probably had from the factory. With the stock cam I would bet you wouldn't have to turn it 5000, as my guess is it would be on the way down big time powerwise at that point. I would think it would live at 5000 though, even though it has what I would think is a heavy piston, BBC's have strong rods compared to the SBC stuff I have mainly messed with. Clay

JavaJeep-INDONESIA · Posted: Sat Jul 30, 2011 5:50 pm Post subject:

Here's a photo of the turbo while still mounted on the Lycoming TVO-435 engine , I kept the waste gate , carb and all the components associated with the turbo

I also kept the dry sump pump Smile

JavaJeep-INDONESIA · Posted: Sun Jul 31, 2011 3:36 am Post subject:

The Chev BB truck engines are strange , there's seems to be little information on them on the internet

I wasn't even aware there was a 366 BB until a month ago , I thought the smallest BB was the 396

clay · Posted: Sun Jul 31, 2011 1:24 pm Post subject:

Once you get into truck engines, things can get weird - no doubt. I know Ford had some weird displacements in trucks too. Not sure about the Mopar crowd though. I'm thinking not a lot out there because anymore displacement rules - especially with the availbility of the lower cost (China made) stroker cranks but if you have one and turbo's are in the future - there's power to be made. Clay

JavaJeep-INDONESIA · Posted: Sun Jul 31, 2011 1:52 pm Post subject: Turbo Photos

The exhaust turbine is approx 2.75" dia on the intake which would make it approx 3.25" inside the housing , 11 blades

The impellor (intake) is slightly smaller 2.5" dia so approx 3" inside the housing , it has 8 blades however each blade is a 'double blade' (see photos)

On the housing it has A/R 1.83 cast on it

JavaJeep-INDONESIA · Posted: Sun Jul 31, 2011 3:09 pm Post subject: More photos

Big Dave · Posted: Sun Jul 31, 2011 5:01 pm Post subject:

A 366 is a very, very small bore engine. Think of it as the 305 of big blocks.

The 366 has a special cam that makes all of the engines power at under 3,600 RPM with a red line of 4,000. It is a very high torque engine camed to act like a small diesel. You can swap the cam out for a regular cam grind cam but the engine has a two gear gear cam drive like the six cylinder does so it rotates backwards from a chain drive cam. So long as you buy a reverse rotation cam shaft you should be fine (there just are not a lot of them listed in most cam books).

You can increase the bore out to 4.125 inch and use 396 pistons (or even run 402 sized pistons by boring it out to 4.155 inches) with a longer rod required to get the piston to the top of the bore.

You can also sick in a longer stroke crank shaft (either the 4.000" 454 crank or a longer stroke aftermarket crank). Just remember that the oil gallery runs along the drivers side oil gallery and this is one time you don't want to find oil by putting a 4.750 inch stroke crank in it. In the old days before aftermarket blocks, they used to make a 632 engine by ruining external tubing to feed oil to the engine so that it cleared the crank swing inside the engine. The heads have very small valves which is appropriate for a small block sized displacement.

It is a four bolt, high nickel content block, filled with a forged steel 5140 alloy steel 3.760 inch stroke crank and the same forged steel rods (that use the small 0.3750 inch rod bolt) that all big blocks use stock. So it can handle the boost you are planning to throw at it.

If you want a high torque engine I would rebuild it stock as it was designed to pull 37,000 pound loaded trailers in a semi. If you are expecting RPM's above 4,000 RPM look to a new cam.

Big Dave

JavaJeep-INDONESIA · Posted: Sun Jul 31, 2011 5:31 pm Post subject:

JavaJeep-INDONESIA · Posted: Sun Jul 31, 2011 6:00 pm Post subject:

Here's a photo of the J20 before it was totally stripped down to do a chassis up rebuild

clay · Posted: Sun Jul 31, 2011 6:18 pm Post subject:

From what I have seen truck engines are really detuned as far as camshaft and compression ratio. My thinking is they are designed to live at w.o.t. basically their entire life. That kind of pulling builds a lot of heat in the piston and combustion chamber which speeds up the burn rate - hence the lower compression ratio to compensate. As Dave mentioned camshaft specs move the power down in the rpm range because all that weight slinging around can stay together at 3000 rpm but not at 6000 rpm all day - day after day. I'm going to say the turbo you have may be a little on the big side, but all that will do is slow down response. However in your application I don't see that being a big deal at all. Clay

JavaJeep-INDONESIA · Posted: Sun Jul 31, 2011 6:44 pm Post subject:

The current engine in the Jeep is a 258 I-6 (headers only mod) and it also doesn't like to go over 4,000 rpm , but it lacks legs on the highway (it's sweet spot is 50 mph) , I currently run 32" tires on the Jeep but want to go to 36" or 38" which will make the 6 cyl even more anemic with stock gears , I figure the V8 will pull the bigger tires with ease and give me a decent 60 to 70 mph cruise (without trailer)