928autobahndreamer

Man, if you really did put "eyes" on the spider, I would be a little hesitant to put my hand in there to work on the engine.

FlyingDog

Leave a note on the pile next to a hammer that says, "Hi hon, I'll help you with the floor as soon as I get done with the car."

I think the plenum needs the "eyes".

SwayBar

Are you going to have the car ready for Memorial weekend at Road America?

hacker-pschorr

Which one? The 79 is good to go - I hope everything is sorted out on the 81 by then.

SwayBar

Were you able to set up a dyno date including Todd?

I'm interested in knowing the output of both cars.

928SS

not trying to start a cat fight, but I REALLY like the look of the murph kits... very nice & congrats!!!

hacker-pschorr

Now that my clutch is working fine - and air / fuel is looking good I'm going to try and set something up ASAP since I wand a proper before / after dyno. Once that is complete, stock exhaust is coming off in favor of 85-86 manifolds and the pipes Mark Anderson is sending me. Who knows, maybe Keith will let us use a lift to swap exhaust at this shop, do both dynos same day!

No cat fights here - I think we've all gotten the boost pissing matches out of our system. Each setup has merit, pros and cons, and all have a place in the 928 community.

heinrich

My beloved Saint Bernard with whom I grew up, would know what was going on just by looking at facial expressions. Smile means yes, nod means yes, rolling eyes means maybe, frown means no way, shaking head means don't even try, wide open arms mean "OK jump into my arms and slobber me till I'm ready for a shower"

FlyingDog

I think there would be a lot of people interested in a new exhaust with stock manifolds vs new exhaust with 85-86 manifolds dyno comparison.

hacker-pschorr

Matt,
I agree, I also have to apologize in advance I will not be the one pulling this off. When my new exhaust arrives, I’m putting it on with the 85-86 manifolds. Some kind of adaptor is needed with either manifolds, having two made up is beyond what I’m going to do with these experiments.

If my suspicions are correct, the stock pre-84 US exhaust is very restrictive or mine is broken (or both). The amount of air pressure you can hear exiting my exhaust is unreal. I’m not talking about BWWAAA either – it sounds like an air leak in a tire – a very large rapidly leaking air leak. To put it bluntly, my car sounds constipated with the supercharger forcing so much air through the exhaust.

A dyno day is in the works, should happen very soon. I’m going to try and connect a pressure gauge to my exhaust (pre-cat) to see what is going on.

My advice – if any OB owner is going to spend any money in exhaust upgrades, it’s stilly to leave the stock manifolds on. Either go all the way or do not bother. 85-86 manifolds are out there in scrap-yards for not much money.

My 79 is a rocket, only upgrades are MSDS headers & straight through exhaust. It trounces my 81 (before the blower).

FlyingDog

That exhaust system should bolt right up to the stock manifolds if I remember the X-pipe discussions correctly. There was a local Rennlister with a stock downpipe that collapsed internally (double walled pipe). I never heard the car with the bad piece, but the description of what was wrong sounds similar for what I remember.

Just be glad you don't have the MSDS headers on your 81 with the clutch problems.

hacker-pschorr

If this new exhaust is a direct bolt on - I'll take donations to do a dyno run before I install the new headers.

I know about the collapsed pipe issue, I have a funny feeling mine may be suffering from this. If the dyno number with the SC is significantly low, I’m thinking about dropping my exhaust right there, running again right of the stock manifolds. Cover your ears.

PorKen

I was wondering something about MAF/MAP conversions the other day. L-Jet supposedly has acceleration enrichment by virture of the AFM door swinging wide momentarily when you open the throttle quickly.

Without a TPS, how do the conversions handle quick throttle openings? Or is it even an issue?

hacker-pschorr

I have a EuroS TB with a TPS already attached.

hacker-pschorr

Dynojet numbers - before was 160rwhp. I did swap out the stock Y pipe / CAT unit for an SS collector to a test pipe after the base line when I installed the blower. I am still running the stock cast iron manifolds.

At 6,000 rpm 6psi of boost, DynoJet results:

311.2 rwhp @ 5,423rpm
321.7 rwtq @ 3,915rpm

It's late, I just got home. These are the peak numbers - I'll post the charts when I get a chance. Top end is still too rich, need to rethink that setup and what to do with fuel. I'm loosing power in the top end. I'm already at 10.9:1 air/fuel @ 4127 rpm. It's getting richer as revs increase.

This is with stock timing = 23 degrees @ 3,000 rpm (hoses removed)

Fuel pressure at 6,000 rpm is 90psi - this is too high at 6 pounds of boost. With my current setup, dialing in better air / fuel for top end hurt the lower end / cruising mixture so this is where we left it.

1 step cooler BOSCH coper plugs gapped at .023

What a ride - I am now glad I left in the twin disc clutch.

Next step is 85-86 SS manifolds and 10psi of boost.....and more tuning.

EDIT -
I forgot to post the results with the A/C on:
296rwhp
309rwtq