The age-old Q: 2.7L or 3.2L?

[l33t9eek]

RS,
I think it's a $$ thing. To recalibrate a MFI pump costs about $1000 everytime to you make a change to the engine. Cams, compression, displacement changes all require a different space cam within the MFI pump. OR in the case of EFI systems it requires dyno time to get right and that also costs $$$. Carbs are just to easy to work on, too flexible and cheap to tune. The cash to HP ratio is just too high for injection.

Cost comparison:
Carbs:
$1000-$3000 for hardware.
5 hours to tune?

MFI:
$1000 Pump rebuild
$900 Throttle body rebuild
$300? injectors
EFI
$1200 throttle bodies
$200? Injectors
$1500 Computer management
$500-1000 dyno time


It's just a simple matter of economics. The "low-budget" racers use carbs because their simple, flexible and cheap. The high dollar racers use EFI to extract the last bit of HP out of an engine but it require cubic dollars.

just my impression from what I've seen and I'm a relative newbie to the porsche world.

[cosley]

A Motec system starts at $6500 +, and dyno time
A Haltec system starts around $5000 +, and dyno time
The PMO kit starts at $3000 and by the time you change the pump, and a few other things you might be into it under $4000.
When I talked with Gus at PFI he implied there isn't much you can do to a mfi pump as far as changing it for different cams etc. He said even a sport muffler can make one hard to dial in.

[RSupdate]

Thanks guys, much appreciated !!!!

Great breakdown for me !!!!

[l33t9eek]

Thanks cosley I didn't know the exact #'s for the EFI system, just the $1200-1500 for T-bodies.

[GRMPer]

I had my 69E pump rebuilt at Jerry Fairchild for $450...and as for getting stacks rebuilt, I'd think that for track events, a little leakage around the shafts wouldn't matter a bit, the plates would be near WOT most of the time....would only really matter for idling and emissions. Injectors can be cleaned and flushed if they're only a little gummed up, all six for $75 in my case.

Just my cheap-ass $0.02

Per

[ckissick]

Thanks for all the input, all. I've been searching for the right solution, and my limitations are money and time. My wife won't let me spend too much, and I have two small girls that require a lot of my time. Rebuilding will just take too long. Maybe when the kids get older.

I think I found just the thing: a freshly re-built (0 miles) stock '78 3.0L engine for only $4K. The low price made me suspiscious, but it's being offered by a shop that is highly regarded on these web pages. It was a budget re-build, but should be reliable. It didn't include the hydraulic chain tensioners, so I'll put those in. It'll still cost extra for that and other ancillary costs, but the next best find was a 3.2L with 95K miles for $7500. I'll put my SSI's on the new engine, and maybe the Webers, and boost the hp to 200-210, with nice torque. Regardless of the above opinions, Bruce Anderson does say that the carbs, while only adding 10 hp, will feel like a lot more on the throttle response. It should be a nice engine in my light, little old '70.

[cosley]

With my 2.4 S motor the thottle bodies had such a carbon build up that 2 of the idle adjustment screws didn't work, and the linkage was pretty worn making set up a waste of time. Before I did the mfi pump & throttle bodies we dynoed the motor at Jerry Woods, 207 h.p. one day and 202 h.p. the next.
'73 S coupe
'73 targa w/3.2 track/street
'68 v.w. crewcab w/2.4 weber motor/5 speed

[chuckw911e]

Originally posted by ckissick
It should be a nice engine in my light, little old '70.

A 3.0 with carbs and SSI's really does "motivate" an early 911.

I'm happy with my conversion.

Chuck

[Shawn]

a sweet 2.9 liter MFI with zero miles. I wonder what 300 hp cost these days?

Drool. Shawn.

[ckissick]

Chuck,

I printed 22 pages of the documentation on your conversion. I'll be studying that when the time comes, but as I have a '70 with a 2.7L carb'd engine, my conversion will be simpler than yours. I'll also use a conventional ignition system, and I'll keep the original 901 tranny. Any specific tips on my particular project, based on all the knowledge you recently gained? Thanks.