How are you deriving the flywheel numbers? Just assuming a drive train los %, or something more scientific? Tnx for the degree wheel info,
For these cars, the loss works out generally to 17% or so; this is an approximate correction which seems work out pretty close across the fleet, i.e., many US spec 3.2s dyno I've seen out close to 216 rwhp (a bit more with a tubi).
Wow! hadn't realized that 3.2s had that more punch than the QVs! My Euro 308 QV dyno'd at 183 rwhp last summer & it was the best of the 308s being tested that day. Of course there's dynos & heartbreaker dynos...
Well, if the 17% loss holds true, that would put your car at 220 hp or so at the flywheel. I forget what the qv car specs out at, but that makes sense based on 20+ hp jump over the 2 valve with similar cams and K-jetronic induction. Besides the displacement and compression changes, we showed here that the 3.2 intake cams had more lift than the qv with the same duration. I think an easy thing to do would be for qv guys to drop in a set of 3.2 intake cams at belt change. The exhaust cam specs are identical. The biggest frustration I have is with the persistant 10 hp loss at the airbox/filter. James said he felt it might could be tuned to almost 250 rwhp without the box (>300hp flywheel).
Here are some Ferrari dyno numbers gleaned from a Tillman! post a while back from a Ferrari Dyno day. All are rear wheel hp: The most comparable graph to the Weber 3.2 with cams is from Mark's 1994 348 dyno from that day shown below. While the increase in peak rwhp to 240 is really good for a 3.2 liter with a 9.2 compression ratio, the surprise is the increase in torque to 203+. The 328 that made a terrific 222 hp (usually 328s run around 216 or so) on their dyno day produced a best torque of 187.4 ft-lbs; that increase in grunt is a pretty usable improvement for a heavier daily use car like a Mondial. Image Unavailable, Please Login
Doesn't this seem a bit low for a Euro QV? I thought they were about 245 at the crank? Do you have any US emissions taking power?
This is all sure very interesting, and I think its awesome that Russ had the confidence to dump the CSI for carbs. But what I am curious of, is the original Euro spec 308, was "claimed" to produce 255 HP. With all the people who are on this forum, and those who, like myself, alternate to the other forums and "TheList", I have never heard anyone quantify what the first euro 308's actually had for camshafts. I have heard plenty of speculation, but never anyone who outright said they had X lift and X duration. I have meausured my own engine, and have Wiseco Piston Companies own admission, that all the 308 engines, including the QV, have pistons that stop short of the top of the cylinder .055", and that none of them will make actual spec compression unless the motor is decked. Some (Norwoods for one) have speculated the dry sump system on the euro motor was worth 15 HP, to as much as 25 HP, which could explain the US cars initial drop to 240 HP. In that light, 290 HP is way cool. I really wonder if any of you guys would know what a wet sump 308 with 10.5:1, port matched intakes and exhaust, with P6 cams would produce on a Dyno, ballpark figure.
We brushed on the subject in post#75 on this thread: My bet would be around 270 - 280 hp, maybe more if the heads were ported. The low end would probably take a hit, but still streetable. The more I think about it, I know you are right that 290 hp with only a 9.2 CR from a 3.2 liter engine is amazing - and with relatively whopper torque and tolerant of street gas! And for me, more than half the reason for me to do this was that is was fun and now makes my car very simple, lighter and DIY friendly. Next year's trick, ceramic coated headers.
Great numbers Russ...it's got to be a whole different car to drive than it was when you first got it.
With respect to what a 2V 308 wet sump motor can do: The last hot rod, N/A 308 we did made 310 hp (crank) with a 9k rpm limit. The cams were - Int. 277 @ .050, 108 l/c Exh. 259 @ .050, 93 l/c Heads were ported - no flow numbers Carbs were - 42's Ignition - Direct fire 38 total Comp. ratio - 11.4/1 Exhaust- big primaries w/ not much muffler It was a 'street' car running on race fuel, not much down low but pulled big in the middle and on top. We had done some 3 liter motors long ago that we had making near 400 for the 2valves and 400+ for the 4 valves. They were race motors with EFI, individual runner throttles, direct drive cam gears/belts, 12k rpm, etc.. On the 3.2 that Russ has the nice thing about driving it is the super flat torque curve, it pulls hard from the get-go but gives up at 6200. Different venturies may help that, larger carbs may be even better. It sure feels and looks like it runs out of air, and I don't think it is running out of cam. If it would hold it's head up for another 1000 rpm the numbers would take on an new level of impressivness.
Well, sounds like the 36mm venturis will be going in for sure to replace the current 34s. Now, anyone have a set of 44DCNFs? Again, many thanks to James and Mike for terrific work!
You can at least rest assured that your engine's output is consistent; looking at that 2nd graph with the higher peak torque, note that, for some reason, the "tails" of the traces at the beginning of the run go upward instead of down, but the extra 10 ft-lb is purely related to an oddity in the data collection method, but the actual curve is consistent from run to run.
This is very impressive. What do you imagine will be the difference in 0-60 0-100 1/4 mile etc with the new cams? I am also thinking of going this route and wondered how much difference it will make in the real world.
Thanks - While I have not driven it yet, I am hoping that with more rear wheel torque than a Mondial t (same 348 engine, graph shown below) and similar rearwheel hp that the performance numbers should be the same. Would expect to find 0-60 right at 6 seconds or so and a 1/4 mile time in the 14s. I think the road perfornmance with the increased torque will be very interesting. I am really hoping that I can get the perfect accel pump set up for the instantaneous response Webers are known for and that the K-jet just did not have. And, as James relates, I still have room to tweak some more out of it through larger induction with venturis or larger carbs/TBs. Of course the simple elegance, weight loss, sound, personality, reliability and DIY ease are important. And at least to me, the engine now looks like the classic work of art it was designed as - with the Weber quartet singing their famous Italian aria... Approximate graph attached of comparative rear wheel numbers of 348 and carb/cam 3.2; I see what James means about running out of air If we could get more air to it up high, the curve should continue higher; will start with the larger (and rare) 36mm venturis when I get home and look at some airbox options. That airbox was only ever designed for a 255 hp 308, so this is probably to be expected. Will pull out Philip Airey's specs for the 308 LeMans Air Box as well as the Michellotto ones and see if there are some lessons there. Perhaps with these cams, the larger flow rate with individual carb filters would supercede any loss from engine bay heat... Then, there is always the Home Depot Weber air horn intake mod for $7.00 pictured below... best rt Image Unavailable, Please Login Image Unavailable, Please Login
Completely stock Euro. There was another all stock Euro there that day, came in about 9 hp less than mine. Both cars were in good tune. Both cars had multiple runs that were consistent. My mixture was being tweaked between runs as it started out too rich. Each run gave 2-3 more hp! Only other 308 was Birdman's '77 carb'd car with the carbs badly out of tune. It came in way below the 2 QVs. Has since been tuned up, so it should dyno much closer now. It's been said many times that Ferrari's OM HP numbers were 'optimistic'. This tends to support that. Have been told that make of 'dyno' was very accurate. Those HP numbers were after the meas'ts were adjusted to the auto industry standard test temp, air pressure, etc. test conditions. We were told that running on that make dyno anywhere in the country should produce extremely close results. Since then I've also been told by some guys into performance tuning that it's what's known as a 'heartbreaker' dyno because it's results are carefully calibrated.
SAE horsepower ratings are corrected for atmospheric variabilities, and should pretty evenly compare dyno to dyno with minimal variation if the dyno is working well. Attached below is a dyno gleaned from the FChat archives of a carb 79 308 for a reference. Image Unavailable, Please Login
Verell and Russ, what brand dynos did you guys use? Different dynos do give different readings, particularly different brands. I've always been fond of dynojets because they seem to be pretty good from one to another. I used to road race bikes and had my bike on 4 or 5 different dynos and always got within 1% or 2% of what I got in my home town shop. A buddy of mine dyno'd his car on a dynojet and a mustang (I think) and lost something like 10% on the mustang. I've only had mine on dynojets I've seen numbers for QVs at 195-197 and 328s at 210-216 on dynojets. Using 18% loss (which I think is about the right number for a transverse engine), that puts the QVs at 237-240 and the 328s at 256-263. Pretty close to advertised....a touch under using Russ's 17% number, but still very close. One think to note, the graph of the 78 shows the engine dropping a cylinder intermitantly from 5800 up, so I'm surprised the numbers are as good as they are. It looks like 165, which is about 201, pretty close to 205.
Mark, The dyno runs referenced in my quoted post were run on a dynojet 248c, that was my bone-stock 328 @ 222hp, and I have a separate set of runs done several months earlier that went 217-223 HP. Just shows how much Russ has accomplished The 79 above was having spark problems at higher revs, new wires fixed that later. Just a datapoint. Image Unavailable, Please Login
I've only ever used Dyno jets, and I'm not familiar with the Mustang although I have heard of it. Mark, it was you or Philip that razzed on me for using 18% before so I backed off to 17% loss. I must say the 18% loss gives better looking approximate flywheel numbers. So, using Mark's 18% loss, the 3.2 comes out to 240.2 SAE rwhp = 293 hp flywheel 203.4 SAE ft-lbs = 248 ft-lbs flywheel The more I look at the 3.2 graph I realize while I have a great improvement, the more I see I am running out of air before I run out of cam. Will definitely drop in the bigger venturis and maybe look at air box options (e.g. see thread http://ferrarichat.com/forum/showthread.php?t=72629 ) down the road. The big torque increase also suggests this as with the Webers and increased intake cam lift, you'd expect a little more torque across the band.
It wasn't me....I like to use the biggest numberI can possibly justify The way the torque crashes at 6000 definitely says you are running out of air, but experience with the engine is the way to know why. James thinks it's the carb, so probably the best place to start and hopefully it's that easy. You might want to re-run without the air box too, if it was a bottleneck before and was costing you 10 hp , you may find it is still the bottleneck and is costing you more now. I've seen the before with aircleaners and exhaust systems, they seem to have a flow capacity which locks the hp and until you find it and change it, nothing else will help. Again, great results....and the last few hp are always the hardest to find.
James said that he did do one dyno run with the box on and no filter, and still had most of the hp loss. The actual airbox is the problem. Cool. Will definitely look at fitting a Michellotto or 308 LM airbox. Pictures of each are in the now legendary airbox restriction thread.
