The first question I have is related to modifications to the engine shelf pieces required for the 6-cylinder conversion. I noticed the Patrick Motorsports sells an expensive engine shelf kit for the 6-cylinder conversion. But, since the 6-cylinder is going into a Racecar, can I just cut out the entire engine shelf to maximize the available space in the engine compartment? Or, has anyone made a template that can be used to modify the 4-cylinder engine shelf to accommodate the 911 engines? I'd like just to remove the shelf parts if they are not needed. Thoughts on this? How do you other racers handle this. Many more questions to follow. I know there are many conversion threads out there, but it's hard to weed through them to see if they address the question(s) that I have. Plus most of Tigre are for street car conversions, not race cars.

Mike S.

You mean the engine tin, or the horizontal shelf that's attached to the chassis in front of the engine?

On my /6 racecar I got rid of both*. When the car is moving, the sheet metal doesn't perform as important a function as when the car is moving at low speed or standing still.

* footnote - when I flat bottomed the car and put a diffuser on the back, I needed to add engine sheet metal back in to keep the engine bay from getting to 200+ degrees.

Ditto on my /4: no tin surround, it's all trimmed off. I don't even run the one that separates the engine from the transaxle area.

I got that idea from Chris Foley, who did that on his race car with his vertical fan system.

Mine has all the tin removed too - "firewall" between engine compartment and rear trunk is still there, but the floor of the trunk area is removed allowing easier access to CV's and starter.
I'm overdue to photograph mine - been too busy working on it. I'll snap some pics next time I've got it up in the air - hopefully soon.

That would be great! Thanks.

I’m not running any engine shelf or tin either.


Did you get conversion parts with the motor?

Drivetrain came out of another 914, but the only conversion part that came with it is the engine half of the front engine mount. So I will need engine oil tank, external oil cooler (?), transaxle pump and cooler, headers, etc. I also need a dual plug distributor. So if anyone out there has anything on a shelf in their garage and wants to sell it, please let me know.

Many go with JB Racings distributor. Jbracing.com

JB Racing distributors look like they are just what I'm after. Since I do not yet know much about these 911 motors, does the distributor rotate counterclockwise?

My -4 has FAT 911 fan shroud with no additional tin and a shrouded rx7 cooler up front, engine shelves on chassis remain in place.

My -6 is more of DE/track than street, but I do take it on the street still, but I run fiberglass engine tin. I have a non shrouded cooler up front with dual fans.

Both run 180-210 on 110 degree track days.

I have an Electromotive crankfire ignition, on the dual plug 6. Old tech, but seems to be easy to tune once installed correctly…

Not great, but here are some pics of my engine compartment. My engine has a 911 style (FAT Perf.) fan shroud so it's similar to your 6 cyl fit, but more space between fan and firewall. I do have a dry sump with the oil tank taking up some of the drivers side engine compartment. 6 installs typically put the tank up in the front trunk. My car has 2 coolers in front with lines back to the tank. I'll take pics of that soon too.

Rear trunk area cut out for access to trans, cv's etc
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The original "shelf" with the channel for weatherstripping is mostly intact, but cut away where air ducting from the front was channeled back to the engine. With the 911 type shroud and no engine "side tins" it leaves quite a bit of gap between engine and firewall / engine compartment
Click to view attachment

Oil tank is on the drivers side against the firewall. As said. with a 6 there's probably not room back here so most people put the tank in the front. Mine is a 4 so it has a 1.5 gal tank. You'll want a bigger one for as 6.
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I'm overdue to put together a photo thread on this car. It's pretty well built. I'll try to get to that soon - ish....

Depending on where you want to drive the car be careful about what you cut out. Many vintage groups will not let you run with the trunk cut for example. Read the rules of where you want to race if that is your goal.

You should also consider the stock location and style for the oil tank. I have run in the front as well on a conversion car I owned in the past.

they will sell you one either direction of rotation depending on the crank/distributor gear you are running.

I also use this distributor.. but build the motor with a 3.0 distributor gear for rotation

Quick question. Why a 2.8? For most groups that makes you too large for the 2.5 group and underpowered for the 3.0 rsr cars we race against....

I went from my 2.7rs down to 2.4 to race with that group.

This drivetrain simply found me and not the other way around, so that's why the 2.8 liter motor. I mostly race with RMVR here in Colorado and have been running with their Small Bore group of 2.0 liter and under. With the 2.8 liter I'll be running with their Mid/Big Bore group, as I would with a 2.4 or 2.5 liter motor. So not much difference unless I venture out and run with other Vintage clubs, which I do from time to time. As long as I have a few others to race against and I'm not running alone all the time, I'm happy.

Is it a hemmigway motor?
Or 2nd guess. Matt in castle rock?

Makes sense and sounds like you have the perfect attitude to just have fun!!!

engine shelf left in, no engine sheet metal installed

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I'm in a similar boat with my displacement at 2.6. SCCA VP2 is up to 3.2L so, I'm not likely to be very competitive - depending on the track.. Portland Intl, where I mostly run does not favor the better handling cars as it's fast and flat. That said, with run groups not being what they used to be, the VP1 cars (up to 1.9L) run in the same heats so there's always traffic (slower and faster) to play with.
The other vintage sanctioning bodies that run around here (SOVREN- Seattle based, and SVRA - Nationwide) would probably place me in some sort of GT class or another, not so much for displacement but for bodywork. Again, probably not going to podium, but there's lots of good racing to be had.

Mine is all removed, great access to everything...
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Both my cars use stock -6 oil tank. Even though I’m already plumbed to the front for cooling, the stock location is already engineered and keep things neat and clean.

So if running a front oil cooler, the stock 914-6 oil tank has enough capacity to feed a 2.8 liter motor, or should I go for a larger capacity tank. I would like to mount the tank in the engine bay and not up front, and actually I'd like to run the stock oil cooler and maybe an additional cooler out back and not cut holes up front and run long oil lines up front and back. But I'm thinking that there may be no way around installing a front mounted oil cooler on a race motor.

On my 3.0 track car I run the stock tank with a cooler up front and the stock engine oil cooler. No issue with oil capacity.

The motors create a lot of heat
Your about to double your HP. So you’ll need a lot more cooler than your old motor

Additionally the cooling at our altitude and humidity is not so great
I run 3 oil coolers on mine with two of them up front
(A 4th cooler on the transmission)

Rpm also contributes to the equation

I’d be very surprised if you didn’t need a front cooler cooler on an air cooled racecar

So what size front oil coolers are people using and what size oil lines, and running lines through the longs? Also what size for the 915 transaxle cooler? Any additional protection on the front of a front oil cooler to eliminate the possibility of damage on the track, like a screen?

I kept the shelf and tin in mine, and also the trunk floor, partly because I mainly drive on desert tracks with tons of dust and rocks, and partly because I've kept the car street-registered so I can occasionally take it to C&C's and shows. So far no issues but obviously it adds some weight and prevents the easier access. I do have a gutted out GT-style lid so the whole engine cover is just mesh and is removable.

Re twin-plug - I have the JB Racing dizzy and dual MSD boxes.

Totally agree re. keeping the oil cool and I have the stock engine cooler plus a large shrouded cooler up front with (IIRC) AN-12 lines in the tunnels. It's a Mazda Competition part from a long time ago with a screened front intake and it dumps out under the car. I've had the car on track at Willow Springs in >110F ambient with no issues. Oil tank and console setup is factory -6.

The recent PMS build sold on BaT vented the cooler into each wheel well which I thought was interesting and maybe not optimal re brake temps (?)

I dump my 2 front coolers through the wheel wells also
I wondered in the beginning if it would impact brake temps...


my mechanic told me no...
said that 200 degree air from the cooler was not going to hurt 600 degree brake temps...

turns out he was correct.
I've never had brake temp problems.
in fact if anything I have too low of a brake temp problem

I started measuring my rotors temps..
had to remove all of my brake cooling to get them to come up to a higher temp... operating range...

in fact had to lower my pad compound to a lower operating range just to get the temps up

had to lower 2 designations on pad material as the first step still didn't bring my brake temps into operating range....

so at least on my car... getting enough temp into the brakes was my problem and not overheating them....

I know I'm running a smaller motor (2.0) than a lot of others do...
I realize that with a much bigger motor, my top speeds would increase that that would also bring my brake temperatures up...

but at least in my application, the oil cooling air... does not negatively impact brake temps

Ok next question. The 915 transaxle that was in the prior 914 was equipped with an external Tilton pump and cooler with fan. Unfortunately that cooler remained in the car and I only have the AN fittings remaining on the case. So I need to reconstruct a cooling system for this transaxle. I am thinking that I can use the same type of Tilton positive displacement pump that was used in the prior system. I would like to use one of the Summit racing aluminum "heat sink" dual pass coolers with no fan for cooling as it keeps things simple and the cooler is more compact and more robust than a finned cooler. The heat sink cooler should do the job as long as air is flowing over it, and since the transaxle only gets hot when the car is moving at speed, air will be flowing. I really shouldn't need a fan for when the car is not moving, and the heat sink cooler still removes some heat in stagnant air conditions, although the rate of heat transfer will be much slower.

Is anyone using a "dual pass heat sink" type cooler with no fan for their transaxle, and if so is it doing the job? Summit Racing has them but they do not have a Btu heat transfer rating for them, so it's kind of a crap shoot as yo how well they will work.

I have both the engine shelf and tin. But for better engine access I had the top angle portion of the trunk wall removed when rear suspension support was added. MarkClick to view attachment

I run a 901 instead of the 915

I ran my trans cooler with three different ducting (intake air) set ups all measured with a trans oil temp gauge

The small electric fan out performed 2 different ram air set ups.

Air flow under the rear trunk is restricted the lower the car is
We put our trans cooler into the rear trunk

I would want to actually measure the effectiveness of any set up

Oiil coolers are all about intake and exits
That’s why radiators are shrouded on production cars
I ran the same front cooler on my old race car with 3 different exit designs and lowered the oil temp15 degrees each time I improved the exit

You may benefit from copying effective race set ups of others
Look at the fastest set ups. Frank beck for example

there is a lot of ambient temp under the trunk... those exhaust headers are really hot and heating the whole area... heat tends to get trapped in that area too....

Agree with this. I have my front cooler dumping to the wheel wells on my 914 racecar and have never had an issue. I have a 260 hp and Wilwood large brakes on the front. I do duct the brakes separately.

On the trans cooler, it's a little tough on a 914, but anything you can do to get the cooler away from ambient heat and provide it a source of fresh air ducting will go a long way. Remember a cooler is a heat exchanger - if it's sitting near the exhaust, etc., it's going to have a hard time shedding heat from the trans oil.

(I put mine in the passenger right rear fender and ducted air to it, but I have flexibility due to full fiberglass widebody.)

My front coolers and ducting for brakes. Don't have any good pics of the plumbing - I'll take some next time I have it out and in the air. Concentrating on the other end of the car at the moment..

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