drive135mph

So I am looking seriously at supercharging my 944, I've written up a spreadsheet and it looks very doable but I have a few questions bouncing around.

1) All the supercharged 944s I see use an external rising rate fuel psi regulator. What keeps me from installing a 951 1:1 rising rate fuel psi regulator, shouldn't it be plug and play, and be cleaner looking?

2) has anyone been to the 200whp mark with the stock 944 fuel pump? I plan to monitor things closely but I'm just curious.

I've started collecting parts, and I'm returning to school so i'm hoping to do this a cheaply as possible without sacrificing longevity. Any insight will be greatly appreciated.

odonnell

Are you starting with an NA? I looked at doing this about a year ago, and I found that it wasn't going to be cheap. I calculated about $1000 for a basic setup - keeping my NA trans (which is terrible idea, the 951 has 205hp stock and has a uprated trans) and clutch. The tuning will set you back a lot. If you follow through, do yourself a solid and go standalone. Dougs951S has a good thread on Megasquirting these cars.

Thread I started probably more than a year ago:
https://rennlist.com/forums/924-931-...-83-944-a.html

(ignore the part where I foolishly make a 175hp estimate of my NA motor, I was being a nooby...)

V2Rocket

The fuel pump and regulator are the same on the turbo and na cars. Pump should be good to 400hp.

Good luck.

Jfrahm

If you are good at welding and fabricating and you don't have a day job then it's sorta possible but not a very good idea IMO. If you have a later 944NA you even have cast rods so I would not recommend even getting to stock 951 power (which would break your trans also). When they figured out the NA internals were strong enough for the 951 they downgraded them.

If you have some weird attachment to you NA then get over it. If you can't get over it (really?) then get a wrecked donor for a driveline swap, but know it'd still be smarter to sell the NA and part out the donor and buy a good running car that does what you want.

The time to blow is after you have the fastest factory version of the car you like and you want to go faster.

just MHO
-Joel

Eric_Oz_S2

Cost me probably $5k to supercharge my s2 doing all the labour myself. Wouldn't bother supercharging a 2.5 na, too many other weak points in the car.

odurandina

^^^all great above (wow)....

the not really worth it posts will be (understating) people's personal experiences and reality-driven facts.

not to mention, our cars, while nice, are getting a bit old.

i would consider a 968, 944T or even Lart's worst nightmare + TPC turbo... (scroll)....

https://rennlist.com/forums/racing-a...oxsters-2.html

.

black944 turbo

Just an FYI. The 951 stock horsepower is 217 horsepower for the US, not 205 and it has substantially more torque at 242 lb-ft, on a standard non s.

If you love the car, go for it. I have seen a few people turbo there nas, however most of the time this ends up costing as much as a turbo to be done properly.

drive135mph

Thanks to all who have taken an interest, I appreciate the build threads and information. It's fun being part of a Porsche community

The Car:

Sentimental Value:
I am indeed a big softy, and I definitely have the wrong car. It's an 87 with a cast high mileage engine. That said, I have had this car for 8? years, It has been with me through tough times and great times. I've owned it so long the seat is stuck in my driving position. It is my General Lee, my Milenium Falken, my flaming chariot carrying me home every day no matter what has gone on.

All great cars are art, a object that creates a a subjective feeling. For me and me alone, the history of this car is a dimension of that subjective feeling.

Engine
I agree the 87 engine will not survive the blower for too long, however I have a spare early engine rebuilt by a reputable local Porsche shop sitting on an engine stand. 9.5:1 compression is bang on for a low pressure roots blower system. In my experience ring pressure isn't what generally kills engines, it much more often heat, usually developed by poor tuning. For this reason I suspect that with careful monitoring the early engine will live a long time in a daily driver role.

Transaxle
Without doubt the NA transaxles are glass, however our transaxles, 944 or 951, are decently cheap and very easy to swap. While I'm sure it will happen when it's least convenient but when it does I have a spare car and not new to rolling around on the driveway.

The Process:

Fabrication/ Cost
For the past 6 years I've owned a shop. I have a full suite of fabrication tools and materials. since I own the materials anyway I expect my fabrication cost to be fairly low. The time dimension is helped by having a spare engine to mock things up on without having to disassemble my car every afternoon.

the parts involved seem fairly cheap, available and reliable through simplicity. I'm planning on a m90 blower. It's over sized for my application but can still be pullied to my desired boost levels.

Tuning
I'm planning on going with a MSD boost master to retard ignition timing according to boost, A rising rate fuel pressure regulator and larger injectors to compensate for the added air, and a wide band, boost gauge and fuel psi gauge to monitor the whole thing. Tuning I'm sure will be a process but unless I'm missing an element It should be fairly doable with the parts listed.
If I'm wrong on that, please correct me.

In the event that I am wrong: I have looked into going standalone, I'm thinking the MS2 box looks like a good fit for my application. However it still doesn't seem necessary to accomplish my goals in my time frame.

Thanks again to everyone who has taken time to read this, If I do go forward with this plan I hope to return the favor by documenting the process in depth so that anyone else going this directions can avoid trouble

SpeedyC2

I do not have the time, money, or (most importantly) the skills to take on such projects, but as an engineer I do LOVE to read about what others with real mechanical know-how can accomplish!

Best of luck to you, and I'll be looking forward to the step-by-step progress reports!

odurandina

the following thread was a classic. a saga for the ages that will not disappoint....

read it cover to cover if you can.

https://rennlist.com/forums/968-foru...velopment.html

inside you'll discover many reasons why some/many/most?? of us look at turbos and big v8s for the next level...
.

mikey_audiogeek

In answer to question 1: A 1:1 FPR won't give you increased fuelling with boost. The idea with the Bell or Vortech RRFPRs with a ratio of 6:1 or 10:1 is that they provide sufficient extra fuel with boost that you don't have to tweak the ECU.

Good luck with your project!

Cheers,
Mike

drive135mph

Thanks Mike but I'm not sure if I get your meaning, If I had a FPR with a rising rate of 10:1 at neutral psi I would be at 50 psi, wouldn't a 10:1 rising rate land me at 100psi at 5lb of boost? My research so far has yielded 1:1 as the industry standard

This link explains better than I can. http://www.turbosmartusa.com/technic...s-an-fpr-work/

Again, I may be totally missing something and am always happy to be set straight

Jfrahm

A regular FPR does not raise fuel pressure to add more fuel under boost, it just compensates for the manifold pressure to deliver the same shot of fuel under vacuum or boost. Otherwise it'd be "downhill" under vacuum and delivering more fuel than expected, and "uphill" under boost, delivering less.

An RRFPR raises fuel pressure in some multiplier to add extra fuel under boost as a crude tuning method. they can work pretty well if you get the right rate disc and whatnot. I would not suggest such tuning for track or ORR work but rather street blasts where WOT is not maintained as long.

drive135mph

Mike:
I think I see what you mean, fuel psi is being bled off by the injectors at WOT and that pressure is being replaced by the FPR staying wide open under boost.

My thought is that the 951 regulator is supplying fuel to a similar engine under similar boost conditions and yielding slightly more than my expected power level. Shouldn't the RRFPR from the 951 be a god fit for my application? What variable might I be leaving out?

morghen

Thats a cool idea, i have a friend who S/C his NA, the car sounded so nice and pulled hard however mileage was terrible and he had trouble tuning the fuel so it wasnt very refined.

If you can control the EFI to follow the boost you will have a nice car even with only 0.5bar of boost.

Not sure about your target HP and torque figures but unfortunately the 944 NA diff seems to be weak. The gears might be weak too, as they beefed them up in the S2 and turbo.
I used to run a 944NA gearbox a few years ago on my 2.0L turbo.
The gearbox worked nicely but one day going uphill on a bridge, ofcourse at WOT and full boost the diff gave up the gost and the crown just munched the gears in it.
It sounded like taking an angle grinder against a metal part.

Now running an S2 gearbox.