Skunk Workz

Take your time to measure the "small nooks and crannies"...the smallest area of the stock IC end tanks are the inlet and outlet silicone hose attachments,i.e the point where the pipes attach,not the "tall and narrow"-section everybody thinks "is so flow restrictive"... And BTW, no matter what you'll do to improve flow through a stock core,you won't see much more than 11 CFM @ 10" more than the stock IC flows...that was the gain seen with a straight funnel attached between the flow bench and the core itself without any end tanks at all.

T Tanner

Dyno day is about one week away, we will see what happens and post the results

toddk911

How about this setup/location??

Dash01

In re: Dyno test of Wolf Pack's IC mods

For a proper test of this IC mod, the car needs to be either moving down the road with wind blowing through it or put some sort of fan on it so the front 1/3 of the IC get proper ambient cooling air to it.

Look carefully at Por951 Turbo's second picture, posted yesterday at 4:44pm. Note that in stock configuration, the tapered end cap shown at the left (front) side is so close to the core channel openings that it effectively blocks much turbo air from flowing through the front ~1/3 of the IC. Now, the front part of the IC is the part that normally does most of the cooling, because that's where the still-cool ambient cooling air first hits the IC and starts the cooling process. By the time such ambient cooling air gets to the middle of the IC, such cooling air is no longer cool. By the time it gets to the back side of a thick IC, the now-heated cooling air is heating air. That's why some experts recommend IC's no thicker than ~3", but ours is ~5".

If you do a bench test of Wolf Pack's (or any) IC without properly simulating through-flow of ambient cooling air, you have not considered the whole effect of the modification, and cannot get truly useful test results.

Back to Wolf Pack's mod: The stock IC is a bar and plate type core, like Spearco. Such cores, by themselves, are considered pretty good. Wolf Pack's mod is to the stock tapered end cap, which he and I think impedes through-flow of turbo air at the otherwise most productive front 1/3 of the IC.

Last night I Googled for pics of various ICs, and of many pics found, NOT ONE but ours has the goofy tapered end cap. Only an '86 Pugeot had a similar configuration, and even that appears to have a more breathable, less restrictive end cap. For those who question this, please post pics or references of modern IC end caps that are restrictive like our stock tapered one. I doubt you will find any, as most I've found have bulging end caps like the one at the other end of our stock IC.

toddk911

Is there any way to design an IC so the flow through actually aids in drawing air in across to cool even more? Some sort of suction effect.

Jfrahm

You are saying that the incoming air is pulling heat out of the charge air at the front of the IC and returning it to the charge air at the back. That does not make sense. The cooling air cannot get hotter than the chage air, and any heat removed from the charge air is good no matter where in the IC it happens. As long as the IC is not so thick that some % of the core is always wasted (little delta T between the cooling air and the charge air) then I would not worry about it. Naturally that is also determined by the temperature of the incoming air as well (a cold day might see significant charge air cooling at the rearmost part of the core, on a hot day maybe none.)

There is room for the thick stock IC, as long as the volume of the IC is not so large as to cause lag I do not think the thickness is an issue.

-Joel.

Dash01

Todd: Yes, add a cowl flap and proper ducting for the cooling air as it departs the IC and re-enters the slipstream. See my prior posts/rants on cowling flaps and fish gills.

Jfrahm: Yes, it does make sense: Consider an ambient cooling air molecule as it comes in through the front bumper and enters the front side of the IC. It picks up IC heat, getting hotter as it passes through the IC, IF the IC has decent through-flow geometry. Thanks to that goofy tapered end cap shown in the second picture, not much charged air can flow through the front ~1/3 of the IC channels. And, looking again at pic. 2, see that at the far back side of the IC, channels there are also partly obstructed by the end tank shape. This means that a lot of the internal flow of the IC is effectively blocked by the goofy end tank, meaning that most charge flow takes the path of least resistance through the middle part, rather than being more evenly distributed through channels across the entire core.

And, unfortunately, our cars have no proper exit pathway or ducting such as a cowl flap, so the now-heated cooling air goes into the hot engine bay, mixes with hot air there, and takes the path of least resistance back into the slipstream, probably beneath the car.

In summary, I think flows of BOTH internal charge air and external cooling air are constipated. Relieve one or (preferably) both flow restrictions, and you should see better IC functioning and therefore more power.

Skunk Workz

^^ This would only hold true if the core itself flowed more than the pipes and/or the tanks that move the air to it,so the air could "choose" to go there ...which it does not,not even close. In the 951,the air is slowed gently,because the area is increased from the entrance to the tank gradually to the point where the tank is attached to the core. This enables the air to follow the internal shape of the inlet tank easier,dispersing air all over the core...resulting in more flow,as measured in a flowbench. The "bulging end tanks" doesn't slow the air gradually,the air just slams in to a huge area,becomes highly turbulent due to the abrupt 90-degree turn and this results in less of the core's area being put to good use (this isn't guessing,this is from days spent in front of the flowbench testing several IC end tank designs on the stock core) ...

Most aftermarket IC's use those round end tanks for ease of manufacturing, and the abundant core areas used in most import cars make up for the flow lost to turbulence...that is the exact core areas we have no room to fit in the 951.

Dash01

OK, Skunk Works, then why does Lindsey Racing replace the constrictive end cap on the stock IC?

Why is no other Porsche IC designed with similar end tanks?

Of hundreds of ICs viewed on Google and eBay (both for sale and past sales), why are none but the Porsche 951 made with this concave and tapered end tank?

And, why did the factory neglect to include a direct and unobstructed exit path for the cooling air after it leaves the IC?

I'm not necessarily disagreeing with you, but want to learn more from others like you who are generous enough with their time and expertise to explain these things to the rest of us. That's the great thing about Rennlist! Thanks for your insight.

And, if you will give me your email address by PM, I'll send you an article about IC design written by someone who knows a lot more than me, and you can see what you think about it.

toddk911

Would spraying the IC with heat disipating paint help any?

Or having the IC ceramic coated???

User 41221

This not a bash at Lindsey, but they are hardly the engineering braintrust of the automotive world. They are "track guys", not engineers, and "track guys" rely heavily on the "trial and error" method to develop their parts. I'm guessing they showed up at the track with a modded intercooler as just one of the things they were trying out on a particular day, had a lot of folks show some interest in it, and next thing you know, its up on their website as a "tried and true" part. They are in the business of selling products, and I would bet their modified stock intercooler did not get much, if any, scrutiny from any of the folks that bought one, aside from hearing somebody claim that its the next hot setup (no pun intended).

The data that they posted on their own website is pretty interesting, to say the least. Between the stock and Stage I intercoolers, they show no pressure drop but they are posting a larger temp differential than with the Stage II, which does show a pressure drop. Huh? Last time I checked, pressure and temp work hand in hand, so I am questioning their testing methodology here, which nullifies the results as far as I am concerned. For what its worth, to properly test an intercooler will require a "rolling road" test, and not just a flow bench or dyno with a fan in front of it. There's no other way that I am aware of to accurately model how the intercooler will work and thats pretty far beyond the means of most tuner shops.

Lindsey builds some good products, gawd knows I have enough of their stuff on my 951. I like Dave and Mike, and I have no issues with them or their products. I believe that they are actively trying to build products that work, I just think the modded intercooler was a "hey, its selling" product for them and they have no real motivation to make a change to it for that reason. SFR, same thing.

If anyone believes that "they said it would work, therefore it must be true", take a walk down any isle of any automotive chain store and look at some of the claims made on the packaging, and tell me if you believe all of them. Slick 50 will NOT protect your engine if you choose to run it without oil. Yet people buy it, right? Its because the consumer finds comfort in spending that money, it makes them feel better about their car. Same thing here. You are "faster" because you believe its faster, not because it is.

Regards,

User 41221

Oh, to answer "why" no one else does the tapered end cap on their intercoolers, thats easy. They aren't building their intercoolers to fit in the confines of a 951, and didn't need or want to put the engineering into it that Porsche did (um, thats not saying that Porsche is gee whiz allmighty, it just means their engineers were given a specific task and used basic physics to solve the problem). People engineering other intercoolers are just solving the same problem with surface area. You might want to look at the "efficiency rating" of the intercooler, I bet the stock 951 piece rates pretty well in that department (I have done no math on this, but would guess the formula "inlet-outlet temp/surface area" would give a good way to compare intercoolers).

Regards,

kasturbo

I'm not pretending to know anything here, as I have not studied any of this, but in regards to the Lindsey design, why would there be any pressure drop from stage 1 and stage 2. They weren't increasing flow, but simply changing the way it flows. The cooler temps are a result of more air flowing to the cooler part of the intercooler right? With the stage 2 they do core changes, so I'm guessing this is what resulted the increased pressure drop.

Until you prove them wrong with your own tests, why are you placing a reason of doubt?

User 41221

pV=nRT

Regards,

Dash01

Todd: I know nothing of heat dissipating paint, but if it significantly dissipates heat, seems to me it would enhance IC heat loss. Ceramic coating is another area I know little about, but wonder if the ceramic might not act as an insulator, defeating heat loss. Copper or silver plating, OTOH, should help significantly with heat loss, as copper and especially silver are MUCH more efficient heat conductors than aluminum.

Scott: I refered to the Lindsey Racing IC end tank mod only because that's commonly known, and not because I have any reason to endorse or disparage their products. For sake of further discussion, pls. address the other notes in my post, such as why no other Porsche or other IC uses a tapered/constrictive end cap like on the stock 951. If the 951 geometry were so great, how come neither Porsche nor anybody else (ALL with laboratories and geeks for testing) ever used this shape.

You may have hit the nail on the head by noting that Porsche engineers simply made this IC to fit the existing sheet metal on the 944 nose--function follows form, and not the other way 'round. This would explain why Porsche did not use this end tank on their other ICs, and why they forgot to make a proper exit path for the cooling air after it leaves the IC. Were they just too lazy, wanting to use the old sheet metal, and/or de-tuning this car so as not to eclipse the 911?

So, does anybody else have anything to contribute on the question about the tapered/restricted stock IC end tank design, and why this car is the only one with it? Do Porsche 951 air molecules act differently than everyone else's molecules?