My beloved Lilly, 1971 145, has received a new cylinder head that was heavily modified by a local Volvo guru. Thanks to a dear friend who sold me the head for a fraction of what it's worth, all the quick and reliable knowledge from the Brickboard, and my supportive family, I am now driving Lilly. I had a blast doing the change over and it went remarkably smooth.
Went for the first real drive today and was happy to feel the car pull hard right past 90mph in 4th gear...yipppeeee.
The next step is to dump the junk Weber and install the SU's I bought last summer at the IPD swap meet. They appear to be in great shape so I think I'll bolt them up and see how well they will tune....

So now I would love to hear all of your expert opinions on horse power estimates as my wife thinks I'm too conservative and I think she is too liberal (with the hp that is :) So here is a run down of what I have done to the motor over the last 14 years of ownership:
Rebuilt, stock crank and connecting rods
.30 over pistons
Cylinder head bigger valves, heavily ported, double springs....Dennis can you add more detail/specs here??
Steel timing gears
Header with 2.5" exhaust
Down draft Weber tuned ~ok~ soon to be replaced by the duel SU's
Full crane electronic ignition including multispark discharge box and powerful PS91 coil.
Iskky street performance cam

And your best estimate is.....

Thanks everyone,
especially you Dennis :))

Wayne

The 1320 foot asphalt lie detector will get you a *very* accurate measurement (better than 5%) of horsepower.

There is an established curve relating horsepower to trap speed. You just need to know the weight of the car as-run to calculate HP.

If you have a drag strip nearby, I suggest making a few runs. No banzai starts or power shifting, no one cares if you red light, you're just going for trap speed. Launch from maybe 4000 rpm, minimal wheel spin. Shift quickly but don't break anything!

Email me and I'll show you the data and how to get your HP.

That said, I'm curious (and my Brick history starts in 1988, so bear with me). Back in my early gearhead days, messing with my Spitfire Mk II (all 1147 cc of it), I lusted for a Weber carb to replace MY crappy SUs. I'm surprised to hear someone want the reverse! Unless you're dealing with a downdraft Weber, of course. When did SUs ever become the hot set-up for Volvos?

2650lbs, 14.6@92MPH = how many HP?

--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

180 HP, based on your trap speed of 92 mph and as-run weight of 2650 lb.

Just a comment - relative to the 100 or so other data points I have, your data shows a low trap speed for the ET, or a low ET given the trap speed. I don't doubt your data, and just suggesting that you're at the outer limits of the "fuzz band" around the whole data ensemble.

The guiding relationship between ET and trap speed is that their product equals 1400. That's not an absolute; that's just a trend, based on the central tendency of about 100 data points. If your car fell exactly on the trend line, for an ET of 14.6 you would expect a trap speed of 95.8 mph; or for a TS of 92, you'd expect an ET of 15.2.

Not to worry; for example, if you had incredibly poor traction, you'd have a high ET for the recorded trap speed. If anything, from the data alone it looks like you have ideal traction and don't lose a microsecond on shifts

Sorry for the tardy response... hadn't been on BB in a couple of weeks.

Smitty

your data shows a low trap speed for the ET

Stock early 144 suspension with Koni D's, 4.10 gears locked & average 195/60-14 tyres. I went to a hoon & tune night at Willowbank did 4 runs with the slowest being a 15.1@89MPH then went home. I put a diff with 4.56 gears in it, but never went back to a 1/4 mile drag strip.

The guiding relationship between ET and trap speed is that their product equals 1400. That's not an absolute; that's just a trend, based on the central tendency of about 100 data points.

I have a Moroso slide rule, it reckons 14.1 is possible for 92MPH.

What do you think of a stock standard '71 142S doing 17.7@74MPH, does that fit it to your data?



--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

180 HP

[(trap speed/225.6)^3]*weight as raced

W,
180hp MAX w/ the current bottom end. That head will go 200hp w/ the right set up. When you drove my car a few years ago, it had that head, and essentially the same bottom end as Lilly. The only REAL difference was my adjustable/dialed in by Rob, FI set up. I may have been 180hp, but I doubt it - never concerned 'bout it. Was LOTSA fun though.
Which reminds me - need to get Madeline "on the rollers" before I pull the current B20/M41.
Rob would be the best one to ask about concerning the head's specifics.
Baisley Hi-Performance (near my house) is an excellent source for head stuff too. I should have suggested dropping it by Dan's (Dan Baisley) shop for a flow test. Dan is a hidden secret in the vintage Volvo scene.
Dan's heads share multiple land speed records.
Rob can also share plenty of info on Dan's B20 headwork relative to what he did for me (now you :-) ).

CHEERS!
D

Depends what the head flows. 120HP is likely the easy maximum from a 32/36DGV or twin HS6. I would use a 500 Holley on that manifold before going to SU's depending on what your goals are (economy/torque or power)

What sort of header? Anything besides 4-1 will work.




--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

The header is one from Jon Parker. 4-2-1

Interesting info on carburetors. Haven't heard anyone talk about a holly. Will it bolt right on to the Weber manifold?

Thanks,
W

350 or 500cfm 2bbl in place of the standard 32/36DGAV is a great upgrade on 2L Pinto's with motor mods. You need to make or buy an adapter + linkages & the Holley needs it's power valve channels reduced to suit a 4 cylinder. After fitting they are a dream to jet.

350: 55 to 58 mains, .45mm power valve restrictors, 4.5" power valve & pump jet cam tweaks.

500: 74 to 76 mains, .45 or .5mm power valve restrictors, 4.5" power valve & pump jet cam tweaks.

10x easier to tune than a DGV, seems to be just as economical & a 10th of the jets. If I had the single down draught manifold, the only thing I would change UP to would be twin DCOE or DHLA's & as much as I love SU's, I wouldn't go back to them except for fuel economy or the stock look.


--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

Pretty sure you don't have a .30 (three hundred/1000s) overbore.
Maybe .30mm (0.012") or more likely 0.030".
--
George Downs, Bartlesville, Heart of the USA!

Yes my mistake. that would be 0.030 over :)

W

Oh yeah,
What plugs would you all recommend??

NGK BP6HS
--
George Downs, Bartlesville, Heart of the USA!

BP7HS always.

BP6HS is for low compression/low performance engines.


--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.

go hotter - I agree w/ the 7's

No, BP7HS is *colder* than BP6HS. Hotter engines need colder plugs.