RKD in OKC

Okay so here's Williams Stock 93 over my 94 x-pipe, race cats, RMB.



The slight difference is the x-pipe?

jcorenman

They do that, when the front wheels aren't turning. I think the PSD/ABS computer figures that since both back wheels are spinning, why not lock them so they can spin together?

Richard, this all shouting "Sharktuner" to me. A Hammer will tell you if the sensors are all working, but you still won't know if the mixture is rich or lean. The only data-point you have for AFR is the dyno-shop's tailpipe sensor, right? The problem there is that the sensor is a few inches away from fresh air, and tailpipe resonance (the wonderful "Bwaahhh" sound) pulls a lot of fresh air into and out of the tailpipe. It's an organ-pipe thing.

If you are going to spend money on performance, you should pay attention to the basics: Air, fuel, spark. An installed WBO2 will tell you where you are fuel-wise, and some time with a Sharktuner will let you do something about it-- as well as telling you something about your ignition timing.

There's no question that a cam upgrade will pay off-- that's the "air" part of the equation. But unless you also pay attention to fuel (and ignition timing), you will be leaving something on the table.

I would respectfully suggest a two-step approach: Swap the cams, do another dyno run; then spend some time with a Sharktuner and optimize the fuel, and check again; and then see what might still be on the table for ignition timing.

The '91GT referenced above is not a good data point, it should be doing over 300rwhp... 275 is S4 territory.

(Disclaimer: I have a Sharktuner and love it, and also distribute them for JDSPorsche).

Catfood

"Maybe my flappy is only flapping part way?"

That is some quotable sheet right there.

PorKen

Note that SAE and STD correction are intermixed in the dyno sheets posted (upper right corner).

Depending on air temp, etc. STD is usually 8-10 TQ/HP higher than SAE @~300.

(I use STandarD in my sig. )

mark kibort

im still amazed that they dont incorporate the conditions for SAE correction. Its one of the reasons I like to do an actual print out too. you can go back and have that printed out, just to see if it was corrected more than it should have been.

all interesting stuff.

seems like there should be a lot more power lurking. we got 40hp just for bolting on 300ccs to scots part euro, AFM version 5 Liter, vs his prior 250rwhp 4.7 euro, with Ljet. seems like 400cc should at least do that to the 5 liter GT or S4. i wonder where the issue would lie.

mark kibort

interesting that the closed flappy seeemed to kill top end HP, is that what Im seeing here? I didnt see this with my dyno runs with a working flappy, then dynoed held open. (easy to do, just tie it directly to the brake booster) and then closed (easy to do, just disconnect the vacuum feed line.

mk

RKD in OKC

After the dyno guy printed out the Std I asked for SAE. He did a weather measurement and entered the results, pulled up the SAE and there was only a 2hp change in either of my runs so I didn't ask him to print the SAE. Said today's temp, altitude, and water was a really good day to dyno in OKC.

Jim, thanks for you input. I think I am going to do the Keith Widom thing and go through the sensors, wiring, connectors, plugs, etc. and maybe even check the cam timing and do another run before I put cams in. I would dislike spending the money on cams and only get 313hp when Keith got that stock and 330 with x-pipe just because of some wiring or sensor issue due to the car being 17 years old no matter how well the service was kept up.

123quattro

I definitely suspect something is up. My 4.7 16v put down 271whp.

Lizard928

Check your plug gap too!
It is possible that your spark is being "blown out"
Try setting it to .023" or .028" and run again.
Also I only recommend Bosch or NGK Coppers. Nothing else. Try a WR5DC+ plug.

mark kibort

euro 84???? thats the bomb!

PorKen

UNCorrected is nice to see if the conditions are good. It shows what the engine is capable of.

Below are the best runs (so far ) from my '85 in SAE, STD, and UNC on a cold winter day vs. summer (same 248x dyno).

SAE (306 tq/305 hp)
STD (314 tq/314 hp)
UNC (323 tq/316 hp)

RKD in OKC

This is interesting...

Doing a search and pulling up dyno charts and overlaying them I found this...



The pink and green with shading is Keith Widoms 93 GTS pre and post x-pipe runs. He was claiming 314 pre and 330 post x-pipe. His hp curve is on a different scale (doesn't cross at 5250rpm), but I just don't see his numbers being accurate as my torque curves are between his and only 279 max hp. The charts are aligned and scaled by the torque graphs.

Interesting how my flappy is changing later.

mark kibort

if they dont cross at 5250, they are not worth overlaying. way way off visually!

mark kibort

my 335 was actual and SAE on that day.

doesnt always work out that way, but in California, most days dont need much correction. if its cold, sure, its brought down a bit and if hot, it goes up, but sometimes not as much as you think, because of barametric pressure being higher. anyway, i usually run both each time to see what i going on and mark the conditions on the dyno sheets.