Best motor per class at Bonneville

ONE37TUDOR · January 04, 2010, 11:53:21 PM

The cup cars run 358 Cu. In. motors.

Beck · January 07, 2010, 08:01:35 AM

The Sprint series cars have a 930 cfm carb restriction.
The Nationwide series cars have a 390 cfm carb.
The heads on the Sprint cars are ported larger to flow the extra air and fuel.
The intake manifold is also different to accommodate the flows.
The bottom end is basically the same.
It wouldn't matter which block was used but the head preference would be the Sprint Cup ones.
I talked to another Nationwide shop today. They have motors for sale also. They do have some Sprint Cup heads available. He said they would put together a motor like this. This guy said he wouldn't send a "used" motor out without going through the top end, changing valve springs. He sounded reputable. He also stated I would not be limited to the restricted NASCAR carburetor. He estimated hp to be 850. Motor pricing was from $12500 to $20000 "depending on what I wanted".
They also had a T101-A transmission available that is illegal for them to run again. Last year they were allowed to narrowed gears in the boxes. They did this at Daytona and Talladega to improve top speed. In that transmission 3rd is 1:1 4th is 1:1.33.
Now that the shopping is nearly done and I tally up all the expensed I realize I have a champaign taste with a beer budget. I just can't afford it.
I need a big dollar sponsor. Try to find one of those in todays economy.

39deluxe · January 07, 2010, 02:29:56 PM

The NASCAR engines are too big for the D, E and F classes anyway. It would be nice to be able to take advantage of all of that NASCAR technology but do you really need it? You could build that 302 Chevy cheaper than any other combination and even source used parts such as AFR heads and intakes ext. Even using an all new forged rotating assembly on a seasoned 4 bolt block would be a bargain compared to the NASCAR shop built engine. Design your own turbo system using used turbos from the salvage yard or even the tractor dealer. It will take a few meets to get it all dialed in and ready to go for that record anyhow so you might as well have fun with cheap parts in case you find you need to change your combo to push that small truck over the record.

Build your own and have fun. After all Bonneville is the ultimate in amateur racing with no prize money and basically no sponsors.

Tom

unklian · January 07, 2010, 03:27:56 PM

Speed costs money.

enjenjo · January 07, 2010, 04:16:03 PM

How about this one. 305 Block, .030 over, 283 crank. this is 254 CI, at the top end of F class. There are some decent heads to fit this block, and supercharged/turbocharged you really won't need the giant ports that the best heads have.

Beck · January 07, 2010, 08:06:05 PM

Quote from: "enjenjo"How about this one. 305 Block, .030 over, 283 crank. this is 254 CI, at the top end of F class. There are some decent heads to fit this block, and supercharged/turbocharged you really won't need the giant ports that the best heads have.

I am not up to speed on the bore / stroke of the smaller displacement small blocks. What is the stock bore on the 305? This seems to me like the math is wrong. The 305 would need a smaller bore than the 283 if the displacement is now only 254. With a bore that small what aftermarket heads would work. The valves would hit the bore. I do like this plan if the math is right.
I see a truck on fleabay that would make a decent body, but it is in Utah. I'm in Illinois. There are none of the early smaller bodied mini trucks left in the rustbelt.
How about some thoughts on the most aerodynamic mini trucks. It has to be 1972 or newer. The latest S10 looks the best but is the body larger than the early ones. Lower drag doesn't help much if it makes a bigger hole in the air.

enjenjo · January 07, 2010, 10:51:34 PM

A 305 has a 3.670 bore stock. There are some 305 Vortec heads that flow pretty good.

Beck · January 07, 2010, 10:54:01 PM

I did some research when I got home.
305 motor has 3.736 bore and 3.48 stroke
283 motor has 3.875 bore and 3.00 stroke
A standard bore 305 block with a 283 crank would be 263 cubic inches
A .030 over 305 with a 283 crank would be 267.3 cubic inches
To get a stock bore 305 block down to the 261 limit on the E class the stroke would need to be reduced to .030 under the 283 crank. This would put it right on the upper limit which may or may not pass tech. Could this be done with an offset ground crank with .030 undersized bearings?
Some of the small block builders are now using Honda sized rods to use smaller bearings. The small journal Chevy V8 crank (283) has 2.3" main bearings. The Honda bearing being used has 1.888" bore. Are these used on forged GM cranks or only aftermarket higher quality cranks? I expect there would be a weird rod length needed so they would be custom built.

In '75 and '76 there was a 262 Chevy V8. It had a 3.671 bore. I don't think the later model larger valve heads wouldn't fit that bore, unless there were valve reliefs cut into the cylinder.

I had commented earlier in this thread that I might have access to a nasty 2.3 Ford turbo 4 cylinder. That motor is not for sale. I asked about building one like it. The cost would be more than the used NASCAR motor so that is ruled out.

enjenjo · January 08, 2010, 01:45:20 AM

You are correct, I had wrong info. You would need a 262 block to use a stock stroke 283 crank. But a 305 block with a GenII 4.3 V8 crank, destroked to 2.90 by grinding to small journal rods will fit in the class.

Beck · January 08, 2010, 10:03:40 AM

Quote from: "Beck"Some of the small block builders are now using Honda sized rods to use smaller bearings. The small journal Chevy V8 crank (283) has 2.3" main bearings. The Honda bearing being used has 1.888" bore. Are these used on forged GM cranks or only aftermarket higher quality cranks? I expect there would be a weird rod length needed so they would be custom built.

I was talking about rod journal diameters here. I have the sizes wrong. The 283 has a rod journal dia of 2.00" The 305 has a rod journal dia of 2.10". The Honda is 1.888" dia. The Chevy sizes I listed before were for main bearings. Taking .112 from stock 283 rod journals would probably weaken the crank too much for use. Prices for these custom cranks and rods would be about $3000, again pricing the motor out of my range.
It would make more sense for me to build a D class (262 to 305 cu in) small block chevy motor which would use more economically available replacement parts.

enjenjo · January 08, 2010, 10:47:45 AM

QuoteTaking .112 from stock 283 rod journals would probably weaken the crank too much for use.

A 3" stroke crank has a lot of journal overlap, rod to main, so .110" smaller would probably work. A lot of the HASCAR cars are using the Honda bearings, so they must hold up ok.

You could also sleeve the block to make it work.

Another thought, 4.1 Buick V6. All the parts from the 3.8 turbo will fit except the pistons. Since it was used in several models for several years, it should not be that hard to find one.

The problem with D class, way to many people choose that class, because the powerplant is cheaper, therefore the record is much harder to reach.