A little over a year ago I opened Mulligan Racing Development, a race and repair shop here in Vista. As is the norm for this kind of thing, it's taken a lot of time and effort and it's been quite a learning experience. One thing I learned early on was that my Turbo race car project was going to be on hold for a while...



Well, things have come along fairly well, business-wise, and its time to get back to work on the Turbo.



For those who don't remember, I've been working on a PCA GT-1r 914 for quite a while now. It has a 3.3l turbo and G50-52 'box from a '91 930 and is a semi-tube frame car. As it sits right now, with everything but the oil tank, plumbing, wiring, paint and a few other bits like diffusers and wings, it weighs 1540lbs. I'm hoping to finish up around 1750 lbs. We'll see about that...

The turbo is pretty thirsty and I needed to be able to finish a one-hour enduro without refueling. That meant a pretty big cell (22 gal.), and that meant a re-design of the front chassis. The first pic shows the front chassis tubes without the fuel cell mount. The front crossmember (911 aluminum) bolts to the bottom of the tube frame just ahead of the rack.

There will be a tube that ties the front downtubes together...

This is the basic fuel cell mount. It's bolted in to the chassis so that changes to tank height or size don't require major frame surgery, just a different mount.

Here's the cell in place. For such a monster tank it actually sits pretty low in the car...

'Nuther...

One of the cockpit...

Other side...

And the expensive bits...

$

I'll post more pics as it goes. Hopefully it'll go a little faster!

Wow, looking good

good to see you are able to get back on the car and that the shop is working out!

is there an adapter plate for the inverted box? Or how does it bolt up? (AFAIK the G50s are like the earlier transaxles with an asymmetric bolt pattern top to bottom)

crazy how light you suspect it will be when it is done - that is seriously light for a -6 with a late turbo box!

Thanks!

You're right about the G-50s having the same bolt pattern as all of the previous Porsche boxes. VWs too. In fact we use a cut-off VW bellhousing as a drill pattern.

Instead of an adapter plate to flip the box, I plugged the engine case with threaded aluminum rod and re-drilled and tapped the case. It required a bit of welding on the lower right hole, but it helped keep the weight and overall length down. It's a pretty tight fit as it is!

The weight issue is going to be fun (or frustrating!) to watch. I've worked all along to keep the weight down as much as possible without compromising safety. All of the tubing sizes were chosen based on the loads they had to carry, so many of the chassis tubes are smaller OD and/or thinner wall than the major cage structure. The only original steel left on the car are the central tub, the bits in the front and rear that are required by the PCA rulebook and gutted doors (still with door bars). Like I said it's about 1540 right now with everything in place, but there are still a lot of fiddly bits to go yet. I'm hoping to come in under 1800 dry and I think it's doable, but you know better than most how those last few pounds seem to add up!

ahhh, dry weight. I tend to think full running weight which was my error. Makes a bit more sense if you consider many racing 6s run ~ 20qt oil systems (are you going to do this??) with all the line and cooler (5 gals of oil is ~ 35lbs) and say 15gal of fuel is ~90lbs to match other 6 racers I have seen, a gallon fluid in the G50 is 6.8lbs, etc and gets it up to ~1935 lbs which seems reasonable if it is 1800lbs dry.

Should be a cool car! What HP/tq you expecting and what boost level? I like how you mounted the turbo, I have been thinking about relocating my oil coolers and mounting one there in mine in fact!

Turbo the V-8? Yipes... Sounds like FUN!

My original weight goal was <1900 running and I think I can still get there, or maybe a touch less if I get fanatical about it! I think that 20 quarts of oil is a bit much. My system is ~15qt. with lines, coolers etc.. The fuel cell can hold 22 gal. but will only be full at the beginning of a one hour enduro. Most often it will only have 12-15 gal.. There is still a bit more sheet metal that needs to be cut out in the fender areas and going to 'glass door skins will shave several pounds, but at this point I'm not quite ready to go URY on the thing!

As for the power, I'm using a '91 3.3 turbo that was rated by the factory at 320hp. at 5700 and 332lb/ft at 4500. According to the guy I got it from it had been modded by Andial into a warmed-up street driver, around 400hp. I've yet to confirm any of that, but the turbo was upgraded so it may be true. Initially I'm going to run it with the CIS, a bigger (than the upgrade) turbo and intercooler, a touch more boost, better exhaust etc., so it will be fairly mild but turn-key reliable. I figure 400-450 isn't beyond reason for a start. Should be a pretty good start in a 1900 lb car.

One thing I've designed for the car is a lot of aero downforce; Front splitter and diffuser, full tunnels under the rear, bi-level rear wing, etc. and I want to have a good reliable engine that I don't have to worry too much about while the chassis is being dialed in. Once the car is sorted I'll start working on making more power. I think with modern engine management and perhaps two turbos that a reliable 600+ hp isn't out of the question.

Hey, nice job on the new gearbox, BTW. That ought to be good enough for the turbo mod...

yeah, that trans has big block written all over it.

I had 525HP at sea level there in CA when at met you... since moving to CO I have lost over 100 of those ponies, and I want them back Boost is about the only way to fix things at altitude. I may just add a 100-shot nitrous plate as well since I really only want/need the extra power in the stretches that are maybe 1/4 mile long at best. Everywhere else I have more than enough power to overheat any corner. And I don't have to worry about dialing back boost and retuning if I travel to lower altitudes to race here and there. I can just change jets if I stay simple and not use the juice.

400-450HP in 1900lbs should be a rocket! I was 5lbs/HP and at 400HP you would have beaten that, 450HP puts you in the 4.2 lb/HP range which will be crazy, crazy fast. Sub 3-sec 0-60s if you can hook it up!

Nice setup. Why didn't you put the fuel cell in the passenger floor board and just build a partition to keep the cell separate from the cockpit. This would keep fuel distribution better through out the race.

Yeah Brett, that was my first thought too, but for several reasons I decided I wanted room for a second seat. I instruct quite a bit and thought it would be nice to be able to carry a victim... er I mean student. Besides, it's nice to be able to give friends, family and potential clients a first hand look at what we do out there.

I think at some point I might move the cell to the passenger side. It really wouldn't be difficult. Sure woud be fun to see the eyebrows go up when you opened the passenger door and plugged in the dump can during a pit stop!

I was thinking a dry break right in the door. That would be even better. No sense in wasting time opening a door.

Wouldn't the look on your vic... errr passenger's face been even better when halfway around the track you tell them they are sitting on the fuel cell?


BTW are you driving the #22 ex-Baker car now? I see it in your avatar.

The sudden realization of why his butt was up at window-level...




Yep, on occasion. It's owned by a good friend of mine and I've been working on it for a long time now. He's had some lean times business wise so it hasn't been run since the PCA Club Race last March, but things are looking up and we're hoping to have it at the Monterey Historics this year.

That car has always been one of my favorite teeners. When you can get more pictures of it please share.

Is your friend the one that owns the red center seat 914 ?
Is it still around ?

Yep. Ron Mistak. Great guy and a certifiable car nut. The center-drive car (GT-1 replica) is still around, we were just looking at it the other day. It needs a new clutch slave cylider, but other than that and maybe a new set of slicks it's ready to go.

The Baker car is one of my favorite 914s too. I saw it race back in the day at the old Riverside Raceway, so being involved with it now is an honor and a thrill.

I've got more pics of the thing somewhere, but for now, here are a few my wife shot at the PCA race...

On the grid. That's Ron behind the car.

Race mechanic in his natural habitat...

Shows a few battle scars after all these years. There will be a bit of rennovation work before Monterey...

A few more pics...

This is the cell sitting in its mount from the back side. The straps on the back are welded to the base frame. The aluminum straps hold the cell to the mounting frame and the whole assembly bolts to the chassis.

Front side showing the aluminum straps.

Here's the front side showing the aluminum straps.

Oops... Sorry for the double post.

Anyway, here is the mount in the chassis without the cell.

And everything together...

Sits pretty low...

I dunno... Do ya think the passenger would realize he's sitting on top of that fuel cell???

Not if you box it in like the rules say....it's been done.....but it's outside of my comfort zone.

You need right side weight anyways. May as well tell the passenger to buzz off. If they are good customers let them rent a seat in the car and see how fast it goes for themselves. Might also look at running two different cells. One in the passenger seat area for your enduros and a smaller cell in the front trunk for regular events where you may be taking a passenger. Would just take a little creative plumbing.

Mike,

Glad to see you're back to work on the turbo 914!

FYI, there's a guy over on the other 914 board who's planning to do some serious aero underbody on a 914 race car. I got the diffuser set up on my 914 for this past track season, and so far results are promising ...

Scott

Cool car Mike!

Hey Mike... thought I would wait until I had some proof of concept before posting about the intercooler location.

I had my oil coolers mounted below the rear deck lid and attempting to pull air from outside, thru them, exhausing below. I would cook the oil with 2 monster coolers. One "winter" project I did was to reverse them and essentially take under hood air thru the coolers and out the decklid and I can assure the vacuum in that area is better full pulling air out than drawing air in.

I ran the car last weekend (on a cool day) and the oil was getting to around 210-220 just cruising the highway (I would hit 300 racing rather quickly so it was cool) and I switched the fans on and it dropped to 180 almost instantly - I NEVER had that good of an effect before.

So I believe it is better to exhaust over the decklid. If you put your intercooler there (I am assuming the placement of the core is for an intercooler or cooler of some sort) you need to draw the hot engine compartment air thru it and exhaust out at the top side. I don't think you want to draw the hot air, so I would honestly recommend putting the intercooler in a fenderwell and drawing outside air there. Or duct air from them to the underside of the cooler.

Thanks for the info! Glad to hear you got your cooling sorted out. 300? YIPES!! Man, that's scary! There just isn't enough air way up there to cool anything...

Actually, the intercooler flow was one of the first things I had to work out when I decided to go turbo. (Unfortunately, I haven't been very good about documenting the project up 'till now... I'll try to do better...)

I started by doing some aero testing with my road car and discovered exactly the same thing you did; that the engine cover and rear decklid are much better at extracting air than taking it in. I thought about putting the intercooler in the fender, but I wanted to keep the piping betwen the turbo and engine as short as possible. Also, the air flowing along the side of the car is rather turbulent and I wanted good clean airflow through the cooler.

So what I came up with was a Can-Am style scoop sticking up behind the roof. This way cool air is rammed down through the cooler and extracted through the engine lid. (Imagine the intercooler sitting in a sort of roasting pan so that the air flowing down through it goes out to the sides and exits upward through the engine lid.) Part of the used intercooler air will be ducted over the upper exhaust and turbo, to help carry away some of the underhood heat. (I can draw a diagram if it would help to see how it's supposed to work!) There is also a NACA duct on the roof just ahead of the scoop that sucks away the turbulent boundery layer before it enters the scoop. The air that the NACA duct takes in is fed to the engine cooling fan.

And besides all of that practical stuff, it looks pretty cool (I think) and makes people wonder what you are up to!

Here's a pic. It's an attempt at a digital pic of a drawing and it came out a little distorted, so I apologise for the quality, but it gives the idea.

Might make a decent air box for the V-8!

oh yeah, I forgot - it has been awhile since I saw your rendering and forgot about the airscoop.

300deg is bad for oil cooled engines but for water cooled it is just "really hot" but, yeah, I want to be able to run more than one track day on a 14qt change I hope that the re-route keeps everything below 280 and I would be happy.