Big Bore Boss build

I'm just about to start this. I've been writing about it in bits and pieces and now I'd like to start a thread to track progress. Parts should be back from the machine shop sometime this week. I'm getting a little antsy to start. I keep thinking about starting the tear down now but I'm trying to do this build with patience in mind and every time I've started a build early something has happened to delay it.

An overview of the build particulars are as follows:

Big Bore Boss block, FRPP cnc heads, Comp 26113 valve springs, special grind cams, Kellogg 3.75" stroke crank, Diamond flat top pistons, Manley 5.85" h beam rods with arp 2000 bolts, Mac ceramic long tubes with a Mac pro chamber h pipe.

The bore and stroke will be 3.7 x 3.75 which will yield 322 cubic inches. The bore/stroke/head combination will result in right at 12:1 compression. Fuel will be primarily E85 but it will also be able to run on 92 pump.

The cams are a special grind. An easy way to describe them is that they have the same durations and lifts as Comp 127500 cams but the lsa is 113 and they are ground with 6 degrees of retard (108 intake centerline vs 102). My plan is to degree and install them locked out with somewhere between 0-4 degrees of additional retard. I keep changing my mind on this. Right now I've settled on installing them straight up and just using the built in 6 degrees of retard.

The machine shop is doing a bore/hone, decking the block, fitting the rings, trueing the rods, balancing the rotating assembly and setting bearing clearance to .0015". The piston to bore clearance will be set to Diamonds recommendation of .0035".

That's the start of it. I'll update with pics as it progresses. A few to start with:

Looks like another full build Bruce. Good luck

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Good luck on the build Bruce. Like you mentioned in your other thread those main caps almost look small. Are you going to dyno it once your done? I'm curious on the numbers.

I was just gonna ask on another thread what makes the boss 302 bigger. Looks like an awesome build. How come you wanted to go with custom cams. I've been researching doing almost the exact same build but I was looking at the 127600 cams and the livernois springs. Also what mad yo decide lock outs instead of limiters?

06 Saleen said:

Good luck on the build Bruce. Like you mentioned in your other thread those main caps almost look small. Are you going to dyno it once your done? I'm curious on the numbers.

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Absolutely. I'm going to work out a gasoline tune first and hit the dyno. Then switch to e85 and re dyno.

In the past e85 while na has only netted about a 10/10 increase but that was with only 11:1 compression and 285 cubic inches. I was also running factory cats. This time around there will be more displacement and compression along with Mac mid length headers so I'm hoping for more of an increase, at least 20/20. Something happens when the cylinder pressure is raised. E85 and forced induction results in big increases and the cylinder pressure of 12:1 is the same as stock 9.86:1 compression with 3 pounds of boost. That may or may not equate to the same power level as a boosted car. It won't be sucking hp by spinning a supercharger so that's a plus. In any case the increased compression will help with e85 and I won't have to be concerned with detonation.

Edit:

07graygt said:

I was just gonna ask on another thread what makes the boss 302 bigger. Looks like an awesome build. How come you wanted to go with custom cams. I've been researching doing almost the exact same build but I was looking at the 127600 cams and the livernois springs. Also what mad yo decide lock outs instead of limiters?

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It's the bore in this case. Stock stroke with a 3.7 bore gives 304 cubic inches.

The cams were on ebay for a good price and they suit what I want to do almost exactly. I'd like a little less lift but it's not a huge deal. The cams are being locked out because that much lift will put a pretty good load on the phasers. It's an educated guess based on others experiences. I may go back to limiters if I think it's advantageous. These cams locked out have a duration range that covers my old cams from 0-10 degrees of retard. Airflow testing indicated that 10 degrees of retard was as good as it got at higher rpms with my old cams so I'm thinking that these are going to work real well installed locked out. I'm pretty sure they were designed to be locked out.

For some reason i thought the boss blocks were 4 bolt mains. ( Not counting the side bolts). Like everyone else, I'm looking forward to seeing your build progress and end results.

Sweet thanks for the info. Are you using the livernois lock outs? Definitly can't wait to see the results!!

Should be very awesome! Congrats Bruce..

Nice man!

very nice !

Gonna be a great build Bruce! Good luck man!

Nice! Cant wait to see it all come together!

Bruce - I'd be curious - any chance you would put it on a engine dyno and then a chassis dyno?

would settle the drive train loss issue pretty well I would think?

Can you run limiters with those cams? It was my understanding that anything over .500 lift you had to run lockouts to prevent piston to valve contact and looking at the cam card it has .535 intake and .550 exhaust. Although I am 98.5% of a retard so I am be wrong on this and knowing you, you already took that into account.

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lethe said:

For some reason i thought the boss blocks were 4 bolt mains. ( Not counting the side bolts). Like everyone else, I'm looking forward to seeing your build progress and end results.

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From what I understand this is the same setup as a GT500 block. It was a concern but it no longer is after getting the block and seeing how many threads engage the main caps.

07graygt said:

Sweet thanks for the info. Are you using the livernois lock outs? Definitly can't wait to see the results!!

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Yes.

stkjock said:

Bruce - I'd be curious - any chance you would put it on a engine dyno and then a chassis dyno?

would settle the drive train loss issue pretty well I would think?

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No. There is one engine builder in the area with an engine dyno but I just can't see doing it. I'm far too impatient, lol.

ford20 said:

Can you run limiters with those cams? It was my understanding that anything over .500 lift you had to run lockouts to prevent piston to valve contact and looking at the cam card it has .535 intake and .550 exhaust. Although I am 98.5% of a retard so I am be wrong on this and knowing you, you already took that into account.

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Anything over .5 lift needs limiters or lockouts. Anything less doesn't need anything. I can go with either and I have a set of phasers set up with limiters and a set with lockouts so I'm covered if I change my mind, lol. As soon as I start tearing into the motor the set with limiters will go up for sale and so will the hot rod cams they are currently attached too.


Thanks for the nice thoughts everyone.

You were using limiters with the hot rods?

07graygt said:

You were using limiters with the hot rods?

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Yes. They were already in the phasers when I did the cam swap so I left them. Previous cams were 127400 which require limiters or lockouts.

Impatient huh.......