931 header + 951 intercooler

[Porsche-O-Phile]

Anyone else done it? I always thought there were subtle differences in the curvature between the later/951 style nose header and the early car header (which would presumably include the 931 with the vents). I am transplanting a 931 vented header onto my 944 now and want to get a 951 intercooler to fit behind there for when the turbo goes in. Otherwise I have to rig up a whole front-mounted intercooler setup with custom plumbing and a bunch of other garbage. So basically I'm just wondering (before I go buy a 951 i/c) whether this is worth pursuing or whether I should just leave the 931 header for looks (or more likely a supplemental custom oil cooler) and plan on having to rig up a custom i/c.

Oh, this is for an early car (I'm fairly sure the 931 header will not match up with a later 944 or 951 directly, the fender curves are slightly different - or so I've been told). The 931 header matches up exactly with the early car fenders, I'm just wondering if there will be room behind it for the 951 intercooler or whether it'll need to be modified (more trouble than it's worth probably versus a custom front-mount).

TIA.

[Rasta Monsta]

The header won't be your problem, it's the radiator subframe that changes between early and late cars. If you can find a late donor to cut one off of, it should be straighforward to weld in.

[Cocacolakidd]

I have installed a few of the 931 vented header panels (Porsche = 924T front plate) with intercooler into 1983 -1989 NA's - they do fit with minimal modifications to the inter structure. The header panel will fit complete without modifications, but the inter cooler installation is to tall to fit straight away. The horizontal radiator support that is directly below the intercooler installation must be cut to allow the intercooler to sit lower and clear the header panel above. I usually cut a U-section and bend it down at the front, not actually removing any metal, and also re-enforce the this cut area with extra aluminum. If you start by laying the intercooler on the horizontal re-enforcement and then starting at one side closest to the radiator draw a line around the intercooler by passing around the front of it and wind up at the other side against the radiator. This is the cut line, but do not cut back within 1" of the radiator yet on both sides. Now you can bend down this cut re-enforcement to allow the front of the intercooler to sit lower and clear the nose panel above it - also allows the intercooler mounts that are already there to bolt up to the intercooler. When the cuts are left 1" out on both sides closest to the radiator and the re-enforcement is bent down if then the intercooler fits and clears all that's good, but you may have to cut back slightly more, and bend down the re-enforcement until the intercooler does fit and clears top and bottom.

[333pg333]

I was going to say they don't interchange (header panels). I've seen pics of people trying to put a vented 931 onto a 944 and it looks wrong. Perhaps this was a 951 though? Can't remember.

[Cocacolakidd]

I have not seen a 931 header panel on a 951 - they probably do not fit well.

Attached a pic of a 1985.5 that is getting ready for paint. It has the 931 vented panel and an intercooler under it. Fits 100% if you make clearances for the intercooler. One note though - On the original 944 header panels there are two screws inward toward the middle of the panel - reached with a long screw driver from the open light wells, one left, and one right. There are not any provisions to place these screws back with the 931 Header Panel - they are always left out.

[333pg333]

Thanks CCKid. I'm sure it must have been 951s that it didn't fit. I have the vents on my car but these had to be 'grafted' into a 951 panel.

I think one has to be careful in assuming that by adding these vents you will increase airflow automatically. In fact it could be the reverse. It could create a high pressure area if there is nowhere for that air to go. This is why I think it's vital to have hood vents (outlets). I have these and it amazes me even on the street, just how much heat comes out of them. Without the vents I am sure there isn't the required flow to warrant nose vents. IMHO.

[ideola]

Originally Posted by 333pg333

Thanks CCKid. I'm sure it must have been 951s that it didn't fit. I have the vents on my car but these had to be 'grafted' into a 951 panel.

I think one has to be careful in assuming that by adding these vents you will increase airflow automatically. In fact it could be the reverse. It could create a high pressure area if there is nowhere for that air to go. This is why I think it's vital to have hood vents (outlets). I have these and it amazes me even on the street, just how much heat comes out of them. Without the vents I am sure there isn't the required flow to warrant nose vents. IMHO.

On the 931, the engine bay exit vents you refer to are on the bottom of the belly pan such that the air is allowed to exit UNDER the car. Also note that the 931 had a NACA duct that drew air into the engine bay and routed it out and down thru the engine bay under the RHS footwell. It's also worth noting here that the NACA duct is dual purpose: draws in cool air while moving, exits hot air while stationary. Suffice it to say, the combo of the vented badge panel and the NACA duct almost certainly create high pressure in the 931 engine bay; I suspect that the reason a lot of 931 owners experience overheating is because they have removed the belly pan, which is critical to the proper functioning of the entire cooling system, particularly on that car, by creating a low pressure zone under the car that properly evacuates the airflow.

Regarding the badge panel itself, the early 924, 931, 924S and 944 badge panels all have the same basic curvature along the leading edge of the badge panel. The 951 has a "bigger" curve to which is mirrored by the front valance on those cars, and also slightly changes the headlight covers. While the 931 badge panel can be grafted onto the 951, it will not match the headlight covers (easy enough to source non-951 covers), but more importantly will not match the curve of the 951 front valance / bumper arrangement.

[Cocacolakidd]

Strange thoughts there - The panel worked well for the 931, no problems. The same intercooler is in behind the 931 panel as in the 951. The only differenct there is that the 951 intercooler has the air ducted in from the grill below - more air resistance here than the 931 direct panel. There is a small amount of air drag because of the vents in the 931 panel but Porsche thought it was neglageble at the time.

As far as air cooling for the motor that is why Porsche installed the under body panels covering the lower side of the engine compartment - these panels actually direct air flow more efficiently to cool the motor, and without them the motor runs many degrees warmer. So this leaves us with the question of whether the hood top vents actually interrupt this flow - Humm ?? I have looked at installing the top hood vents that are pictured, but I am still wondering if they are beneficial or a detrement of the air flow in different areas. Sometimes a slight change will disrupt the airflow and create more drag on the over all car. I wish I knew as I like the look of the top vents.

[Porsche-O-Phile]

Thanks for the info (it's been a while since I looked at this thread). 951 i/c is on its way here and the 931 header is in the process of being installed. I'll follow CC's advice and keep you all advised how it works... I would much prefer having the behind-the-header i/c configuration than rigging something up with a front-mounted i/c with a bunch of custom plumbing.

Sorry this project is taking forever. It'll get done... Eventually...