Dry vs wet sump

Dry sump is amazing. In the worst traffic jam situation in Bangkok, like rush hour, the water temp. on my 308 only rise a bid. So steady, at first when I owned the car I thought the gauge not working properly.... If you have to choose between wet and dry, don't choose, buy dry.....

 

I'm sure you meant OIL temp......

 

reason for the oil temp being - apparently - lower on dry sump cars during comparable driving situations than on wet sump cars is simply because the oil temp sender is differently located on both engine versions.

Dry sump: oil temp sender is located on the bottom of the oil tank and therefore AFTER the oil cooler.

Wet sump: oil temp sender is located in the engine on bottom front side of the oil pan, therefore BEFORE the oil gets through the cooler.

Best Regards

Martin

 

Thanks for that Martin! It really takes a VERY long time to see any kind of needle movement on the oil temp gauge when driving in the winter with temperatures below 10 degrees Celsius....

 

Also wondering about this one distributor and two distributors, does two give better performance when tuning right. What is the reason for two? One came before two and then one again with the QV???..

 

the same on my car. But like mentioned in my previous posting, on the wet sump cars the oil temperature sender is located on the coolest spot.
When it's really cold outside sometimes I plug the driver's side inlet for the oil cooler with a big sponge. It helps ... but only a bit.

The cars seem to be designed for 'full throttle' on southern autostradas and nothing else

Best Regards

Martin
'80 308 GTB

 

I meant water. Since the oil temp decrease, because of separate oil tank, the engine run cooler, water temp. cooler, isn't it... correct me if I'm wrong. But that's what mine read....

 

The dry sump engine doesn't run cooler than the wet sump engine. IF there are any differences, then they are marginal and not to determine via the dash gauges.
Reason for a healthy water temperature under traffic jam conditions is simply because your car has a healthy cooling system. Regard the tremendous amount of coolant on these cars.
If maintained well and properly working, these engines never overheat.

Best Regards

Martin

 

)))))))))

 

I might add that in theory the water temp indication with an engine at normal operating temperatures should be fairly constant (I think about 80 degrees C), no matter what the outside conditions are. This is due to the fact that water temp is controlled actively by the thermostat and the radiator with its thermocouple and cooling fans. The oil on the other hand does not pass through a thermostat, but all of it always passes throught the oil-cooler. Therefore ambient conditions have a greater effect on oil temp.

 

Paul
I am not sure you are quoting James accurately. I can believe the Euro DS cars had 15 bhp more than the US wet sumps. On causality, I'd highlight three factors, of which dry sump would be #3:
- the euro cars had different intake cam timing (4 degrees) -- which btw is an easy mod to do when you are next changing belts. For discussion, see the Allen Bishop book. My gut (and only that, I haven't measured it) is this is worth at least 5 BHP;
- as I have found recently, the orifices on the US headers do not match well with the exhaust ports on the heads. Tate Casey has told me this was a design intent, and, when they've honed out the headers to match, they've measured a 5 BHP gain on the dyno from this one modification;
- third is the DS. While no expert, I am in the middle of a dry sump conversion with parts coming from Norwood. While various claims have been made, the OEM windage tray, to my (doubtless ill-informed) judgement is a well made piece. I believe Kermit has developed a "better" tray, but to date have seen no back to back testing (which will be really hard to do, as an aside) to see if there is a gain in BHP or effectiveness. That said, the dry sump does enable reduced crankcase pressures (a good scavenge pump will even create a vacuum in the bottom end) which will lead to less drag on the crank. How much is this last piece worth? Tough to judge. My gut would be 5 BHP or less, but it is just my gut. Anyone have any data?


Philip

 

At the time I was talking to Norwood, several years ago, I do not know if James had taken over his part of Norwoods shop yet. At any rate, I did not misquote anyone. I was told not only by Norwood, that the dry sump was worth 15 to 20 HP. I would assume Norwood had some testing to back that up. I also note the F430 article in Cavallino explains that the dry sump system does create vacuum to allow the engine to make more power.

On another front is rated horsepower. The original euro engine was rated at 255 HP. From that point on it seemed to drop off. First the US car lost 15 HP, and then apparently in '78, lost another 35 HP, to end up at 205 HP. I have never seen all the cam profiles available, but as compression remained the same, and the euro and early US cars had supposedly the same cams, I am not sure which power output means what.

My car, a 77 GTB, may or may not have its original engine, no way to know and as I cant get the heritage certificate to go through, something dont match. But at any rate, my pistons stopped .055 inch below the deck of the block. Wiseco, who has made me up a set of what will now be 10.4:1 compression pistons, told me that .055" is what they have in their records from all the 308's they have done, including QV engines. There is no possible way the engine can have 8.8 compression this way. I had factory Borgo 9.7:1 pistons, and only when I calculated out the .055" did I get the 9.7. With that drop in there I was in the mid 8's. A stock piston, according to Wiseco, is barely about 7:1. To get 8.8 without replacing pistons you would have to deck the block. This was probably done to give the factory an advantage in racing over a customers car. The intake ports dont match, the exhaust ports dont match, and the wet sump robs power, that bugger will never make 255HP stock that way.

I notice on the 308GT/4 LM, they modified the windage tray. To quote " To protect the crankshaft oil supply, the windage tray 103929 was modified to collect oil from the heads and supply it to the sump well ". Is it possible oil running down from the heads is fouling the crankshaft? That could reduce power significantly if true. The power is in those engines, it just needs massaging to find it.

 

Paul
I had not meant to cause offense, I apologise. The only way to know is back to back testing of the engines. If there's 15 BHP in the dry sump, I for one will be delighted. Some port matching (done), a lightened flywheel (done) and the DS conversion (in progress) will get me scooting round the track faster.
Philip

 

No appology necessary Phillip. I am just quoting what I was told through multiple sources, and I have no personal evidence to support it. Are you doing anything about raising your compression while the motor is apart? I have been thinking about that windage tray though, wonder if improvements could be made. Thats like free HP.

 

Paul
We have the motor out and are doing the plumbing for the DS and other bits I mentioned. No need to open the top end and I don't want to spend the $15K at this time to do the job properly (pistons, valves, D-shaped ports etc).

FYI, I think you'll need to pull the trans to do the tray.
Why not go all the way and DS it?
Philip

 

I am supposing that the 15 hp difference is from the following:

Exhaust restriction from the unbelieveably heavy thermal reactor.
Retarded, (in more than one way), cam timing.
Probably, different ignition timing and curves, (the idle retard doesn't count).
Likely different carburetor jetting.
Parasitic power loss from the twin air pumps.
(and hp loss from the ugly, heavy bumpers)-:

I have a feeling that the crank case vacuum differential is not that big a power robbing factor, otherwise, we would see a bigger gain from goodies like the "Krankvent". Speaking of which, (not to hijack the thread), but has anyone got data on the worth of the Krankvent?

I am not disputing it, but i find it hard to believe that the factory would have a different, (sloppier) buiild quality with regard to port matching on US cars. For sure, individual differences do exist.

Back from the dead,
chris

 

patpong,

I noticedelsewhere the other day the reason for dual distribs in US and other, was the dual point system with R1 and R2 settings.

That would not fit in one unit..

 

my friend Joe has the K&N vent on his car. he picked up one for me as well.... i need to go over there and get it ( and pay for it !)
Image Unavailable, Please Login

 

My motor and trans are spread all over my garage, total engine and gearbox rebuild underway. As far as DS I just cant get into any major alterations right now, starting off just to make it a nice driver for now.
I dont know anymore here, but I was under the impression that an 8 wire dizzy cap would fit a 4 wire dizzy. As both 4 wire dizzys can fit both sets of points, both sets should fit inside an 8 wire dizzy as well. If the caps do interchange, the only part drastically different between the two dizzy's would be the rotor shaft. If that is all true, there must be another reason they ran two distributors. Looks cooler? Better spark at higher rpm for emissions?

 

Also dry sump systems typically have higher oil capacities so there is more oil to share the lubrication and heat extraction duties, in threory you could go longer between oil changes.

 

I had a little falling out with Porsche and the local dealer about this after I bought an '04 996 instead of a 355 . . . the 996 and 997's are not dry sumps, it is a total scam that they are calling it an integrated dry sump!!! . . . there are two scavenge pumps (one for each head) but the third pump is the main feed oil pump . . . there is no scavenge pump for the crankcase. The GT3's, GT2's and turbos have a true dry sump. I did a lot of research on this subject when I was having smoking problems during autox'ing . . . ultimately Porsche wanted to void the warranty for "abuse" instead of fix the problem.

Sorry for hi-jacking the thread . . . just couldn't let P get away with the BS advertising/marketing of their "integrated dry sump" on F-chatters.

Sean

 

Krowbar, the dual distributors did away with the drysump (forgive me if I repeat myself, didnt read the whole thread yet) because of the space required for the lines and so on. You simply cant fit 4 points under one cap for the smog set-up and the 2 seperate timed ignition systems. Its a joke but made it possible to get the car into north america i guess. Sometimes I wish my 308 was drysump for the "cool" factor (and the oil starvation in hard turns) but it really isnt a big deal.

 

You can get 4 sets of points in those distributors and it was the way every European version 365 GTC4 (among others) was built.

 

Sean is 100% correct. Porsche may call it a drym sump in their marketing materials, but it does not fit the normal definition of a dry sump. The last true dry sump in a regular production 911 was the 993. If the 996 had a true dry sump, you would not see this product on the market:

http://www.bkauto.com/porsche/r9095.php

 

Brian, have you seen a 308 distributor with 4 sets of points in it? Mine doesnt have room unless some little elfs make them and install them, dont doubt an old 365 might have come that way but they were probably larger. Still didnt answer the question as to why they came with 2 distributors, makes sense from a packaging perspective because it certianly wasnt for performance and getting to Gino's shop on 4 cylinders isnt a good reason either.