For you small bore lovers

[Hap Waldrop]

I don't get many call these days for folks wanting to do hotmrod 948 engines, most of you just jump up to the 1275, but after not seeing a 948 street engine in a good 6-7 years, all of a sudden I have two to do, stuff always runs in streaks. This forst 948 build is a little unique to say the least, we're using 998 .060 over pistons, which is .120 over for a 948 engine. I bored the block the other day and that went fine, plenty of meat in the block for this bore size, next mission will be to find out how the compression heights pays out on the 998 pistons, The engine will have 1098 rods, blanced, running a APT VP266 cams. Anyway thought I would share with you guys something I was working on that was a bit different, after this engine, I'll be doing another 948 at .060" over.

 

[davester]

I've always wondered how big a difference a 1275 makes in real life. We 1098 owners always feel a little bit of an inferiority complex and I'm sure the 948 owners feel worse. I'm guessing that adding a header and velocity stacks bumps up the 1098 closer to the feel of a stock 1275, and that a cam might put it over the top (of course adding those things to the 1275 would be even better. Do you have a good feel for how those things compare to the displacement difference as far as performance is concerned? Carroll Shelby's motto said, "there's no substitute for cubic inches". However, he dealt in 100s of cubic inches and we are in fact only talking about 11 cubic inches (20 in the case of the 948).

 

[drooartz]

Variety is good, Hap. Keeps your mind sharp.

Keep us informed on how your 948 builds go.

 

[jlaird]

948 engine is 42.5 HP

.060 over to 998 is something 5 HP

HS2 carbs is 2 HP

1275 exhaust is 2 HP

295 head is 8 HP

Cam lets assume another 5 HP

That is a total of 22 HP increase bringing you up to 62.5

Other tricks, like balanceing, removeing weight from the flywheel, etc, should allow you to get to 65 to 70 HP without going crazy and keeping the engine street useable. I know, who is this guy, hay, I had one and made beleivers of many stock 1275 spridgets on a regular basis.

Ok, at 22 HP that is a 52% increase in HP from stock.

Have I forgotten or does a 1275 get 72 HP stock.

 

[texas_bugeye]

Very cool!
My little 948 has pushed my BE around now for a few years.
It has a few of the things done to it mentioned by Jack above.
30 over, Isky cam,header, Hs2's, 295 head 9-1 nice AE pistons and the bottom was done by a crazy bike bulider Geez he was wierd but thats another story.
Jack I dont think it has as much punch as you are showing but it gets up and goes pretty good.

Hap I'M going to watch your progess on these two little fellows.You say you have not done a 948 in 6 years? Thats a long streak I Know that the 1275 is the prefered set up but that is a long time to not see a 948. Are they all gone? Or could it be that the 1275 is getting harder to find?

Long live the little guys!

 

[RickB]

Here's a 1275:

https://portland.craigslist.org/wsc/cto/1376588519.html

This may be another:

https://portland.craigslist.org/mlt/cto/1366116761.html

 

[jlaird]

Chris, get out your copy of Vizard, all the numbers are in there.

Oh by the way I could get 7200 RPM before I got valve float. It was a good engine and I only had to refresh it every three years or so. It was my daily work car for the last half of my military life. Both my kids learned to drive with it and took it to school when I was TDY. Like I said a fine little engine that went like stink. It did not have the low end torque of a 1275 but oh my goodness, at about 3K it would come up on the cam and talk to you.

 

[texas_bugeye]

So I should be at about 57HP So 18 of them would be
1 1000HP Bugatti Veyron !
Thats sort of insane
But 18 Of them would be way more fun

 

[Hap Waldrop]

Other tricks, like balanceing, removeing weight from the flywheel, etc, should allow you to get to 65 to 70 HP

Nah, none of that stuff makes HP, lighter rotating mass just makes for quicker revs, balancing, just smoother operation at higher rpms.

There's no real comparision between the 948 and the 1275, the 948 has 3.0" stroke, the 1275 3.200", the 948 suffers badly form a lack of torque, it revs just fine, but when compared to the 1275 no matter what you do to the 948, it will still have no torque. AS jack mentioned it quit possible that you can get a hopped up 948 to near stock 1275 numbers, but they are still way different deals, one won't have much down low compared to the other, and will only mathc the 1275 at the very top of the powerband, where most folks never drive anyway.

I completely understand why folks want to stay with the 948 for originality, but for pure driving and if you're going to do a performance build anyway, might as well throw that money at the 1275, there are so many more options, the 948 is always going to be a tougher road to hoe.


Now the 1098, thats another aniaml alltogether, with it's 3.300" stroke it has as much torque as the 1275, but struglgles to rev as much as the 948 or 1275.

 

[jlaird]

Oh, don't misunderstand me. Torque changes all unless you are running at the high end as Hap says.

As I said "It did not have the low end torque of a 1275 but oh my goodness, at about 3K it would come up on the cam and talk to you."

I would of course go with a 1275 all things being equal, I too like torque.

 

[Hap Waldrop]

A little update on this project, it well under way, bascily this guy already has a 12G-295 head, and has decked and using it on another 948 bottom end, now I'm building him a a more robust 948 bottom end. The engine is using .060" over 998 piston, which make it .120 over the standard bore of 2.48 of a stock 948, so the bore size now is 2.60", which now make the engine a 1044cc, the 948 block took the bore szie with zero problem, plenty of meat left, the normal 948/1098 head gasket will work fine with even a little room left to spare. The AE 20950 998cc .060" pistons which are flat tops work fine and as for deck height, which no one seem to be able to give me a answer ahead of time, but they work out to about .016" on piston deck height, I was told everything from .060 down in the bore to .010 above the deck, so much for asking the experts Oh it's worth mentioning that AE 20950 piston are a modern 3 ring design.

Another thing to talk about here is the fact we are using 1098 connecting rods, as the 948 pinch bolt I guess could be made to work with 998 floating piston, but using the 1098 rod just let me utilize the floating set up the 998 pistons were designed for. Now on to rod bolts, now i not much for using stock rod bolts, why go to all this trouble to make thing bigger and badder, and then use the stock bots and that silley tab washer set. I search the ARP catalog and found a gneral replacement rod bolt ARP #200-6207 which was perfect for the 1098 rods and would work with zero mods, and would also work fine in the 948 rods as well. The rod bolt look alot like the one that would be used in aftermarket racing rod, and have a 12 point head, they fit into this rods like they were desgined to be there all along.

I'm using the APT VP266 cam sahft with the normal pin drive oil pump set up. The combustion chamber number on this cylinder head, currently they are 24.0 CCs, and with that number, the compression ratio would be little above 10.5 to 1. Wee're deshrouding the combustion chamber a bit, and will be using the 1.31" 1275 intake valve, but staying with the 295 stock exhaust valve size. SO we'll target the combustion size to close to 25CCs and that will get us to the 10.0 to 1 target compression ratio.

I never know what path a customer will take me on with a engine, in the begining, I thought to myself, why not just build a 1275 and be done with it", but the customer wanted people to look under the bonnet of his Bugeye and see a 948, right down to the 950 on the side of the block.

There's ton more work to do, as the dummy build is done down and I know we're OK with piston deck height, and now off to take the rods and pistons back out, and prep the connecting rods, which the customer wanted fully race prepped, which mean the full kit and kaboodle, lathe lightening at the thrust sides and polishing the the beams and full rod body, resizing of the big end with the new ARP rod bolts.

In closing this is what make this job interesting the education never ends, and you always get to do new thing based on the curosity and imagination of your customers, and that makes coming to work everyday worthwhile.

I'll keep you guys updated and promise pictures in the near future.

 

[aeronca65t]

Here's the fire breathing 948 that came out of my A-35.
Note the crank handle drive on the front pully. :laugh:

The "35" means 35 horsepower, by the way.
At least Bugeyes had two teeny, weeny carbs. Mine has a single downdraft with a barrel the size of a soda straw.
Smoothcase trans too (with mechanical clutch linkage).

It's being replaced by a moderate and refreshed 1275 (and ribcage gearbox).

It runs OK, so I may put it in my Midget parts car just for a goof.

 

[Roger]

Nial's engine displays some history with its Zenith d/d carburetter.
Austins for years used Zeniths, whereas Morris, MG and the other Nuffield cars used SUs. Even when they became BMC, some of those habits lingered. The A35 descended from the A30, which was of course a competitor of the Morris Minor with its dreadful sidevalve lump.
When the Minor got the A type engine and a design overhaul, it became a much better car and mostly out-did the Austin - with an SU on its engine. The A35 stuck with the Zenith because that's what Austin customers expected!

 

[jlaird]

Hap, just came back from taking the towel out that I used to clean up my keyboard. What a fun engine.

 

[drooartz]

Very neat to see what you can do with the old 948. I might do something similar if I ever do another Bugeye -- if I ever say I'm going to do another Bugeye, though, someone please shoot me.

 

[DrEntropy]

Awww c'mon, Drew!!! What else would ya have been doin' with all that time 'n money?!?


...not to mention missin' out on findin' all these new friends!! :laugh:

 

[drooartz]

The friends part I would miss.

The time and the money part (mostly the time part, when it gets right down to it), now that's another matter entirely...

 

[RickB]

Drew - obviously you don't have the Tunebug on the road yet. :wink:

 

[jlaird]

I wonder what the hold up is, he's had the engine in for weeks and weeks.

 

[aeronca65t]

After posting my little 35 HP 948, I thought I'd post a truly fast 948.

Not a great picture of the engine, but anyway, this is Ray Stone's 948 Bugeye (below).

When I was a kid in college, I used to follow Ray's exploits racing against the Spreens, Randy Canfield, Joe Hauser, and all the other National level SCCA racers.
(I told him this a while back....he thought it was funny)

Anyway, nowadays I actually get to race in vintage events with Ray. Not that I can stay anywhere near him. His 948 is amazing.
The redline is set at 10K (!!)

If you want to see Ray's 948 car in action ~Click Here~ and slide to the 7:00 mark on the video
You can actually see him shake his fist at an MG that was blocking him :laugh: