hacker-pschorr

Everybody loves dyno threads. Both are 5-speeds

Blue car:
US - 1979 - Stock 4.5 liter 8.5:1 CR - with MSDS headers, custom Y & single 3" exhaust with no muffler

Ignition timing on the 79 is 2 degrees higher than stock, picked up a couple ponies. It could have used a bit more fuel but this is a before dyno so no sense in wasting a lot of time / money on the rollers.

Red car:
US - 1981 - Stock 4.5 liter 9:1 CR - with 85/86 manifolds, custom Y and single 3" exhaust with Borla straight through muffler.
EuroS Intake, runners, Throttle body. LH / EZF with twin dizzy and stock MAF with 42lb injectors.

We didn't do a lot of tuning with this setup, another base dyno to make sure the ECU conversion was working good before the supercharger went back on.



As for the HP / Torque debate......there is no debate, the 81 is faster even with the extra weight (150lbs or so) - at least in a straight line. The 79 has bigger brakes and better suspension.
After 4,500rpm the 79 doesn't even feel like it's still accelerating, while the 81 pulls strong to red-line.






The 79 is the one in this video:

http://www.erik27.com/79928/trackvid.wmv

John Speake

Did you Sharktune the EZ-F ? I think you can usefully pick up some torque/power in the mid range with a bit more ignition advance....

IcemanG17

great data

Interesting how the CIS car is making more torque until 4500 when the L jet takes over.....probably just the better breathing of the intake mods... You mentioned the CIS car was a bit lean.....more fuel would increase its performance quite a bit....I gained quite a bit with more fuel down low...

hacker-pschorr

Yes, I started with the base EuroS map, I removed timing from the WOT ignition map initially to be safe before hitting the dyno. The result above is what we maxed out at.

It was the fuel we could have done better on. I only tweaked the WOT LH map because I kinda forgot it's an overlay to the base map. So the RPM gaps in the WOT map caused a kind of "rolling hills" looking A/F. The spread isn't that wide but we could have dialed it in better. I figured this was "good enough" for a base line to test out the new brains. It was a long enough dyno session and my release bearing started to stick so I called it a day.

You mean LH - no more barn door.

Not really lean, if I had the CIS wrench I would have given it a turn just to see...... After all the time spent on the dyno with the 81 I was kinda spent......also the A/F changes I put the 81 through didn't really make a big difference.

IcemanG17

Here is my before-after dyno run from adding only fuel with basically the same exhaust as your L jet car, but and automatic 4.7L USA

hacker-pschorr

Oh God no, not that lean. IIRC it was in the mid-12's - so damn smooth it looks like the A/F was drawn with a straight edge. When CIS is working, it's quite the system.

Oh yea.....this CIS setup will be 100% for sale soon if anyone needs a good fuel distributor. Line forms at the left

Mike Simard

I have a dynojet run of a stock 79 CIS but with Devek headers and 4" exhaust. It was 229hp and 250 something torque.

I miss the CIS and it's mechanical simplicity, it's almost tempting to round up the parts and do all over again...

SMTCapeCod

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hacker-pschorr

Was the HP fall-off after 4,500 about the same?

I ran this car on the dyno many years ago and scratched my head at the HP curve back then so I checked the cam timing before this run. Problem is I checked it on a cold engine. I wonder if the cams are slightly advanced.

Do you have the data file? I would like to do an overlay of these two just for sh*t's and grins.

It's great when it works, I'm assuming my WUR is the reason why it doesn't want to start when cold.
After multiple cranks it just doesn't want to do anything, then poof....runs like nothing was wrong.

danglerb

I was guessing a little bump for the long tubes on the low end and same for the 85/86 manifolds on the top end.

Same custom Y, was it just a Y or optimized merge?

What were the Dynojet imaginary units, crank or rwhp?

Mike Simard

I think think the dyno curve was very similar, I'll post it as soon as I find it.

If you directly wire your cold start valve to a toggle switch on your dash, life will be good. You'll eliminate the thermo time switch and the mystery of what's going on during cold starts.
You could print a label that says "choke".

hacker-pschorr

Totally different - I'll post pics tonight.

I've never seen a dynojet that does the crank HP calculation, so RWHP STP correction.....as is stated in the upper right corner.

I prefer sticking with SAE numbers but somewhere along the line everyone started posting up STD........when in Rome.

Cool, thanks.


Damn it - I knew I should have started a thread on the issue.........

danglerb

So a comparison to totally stock for those model years on that Dynojet would be what, 180 to 190 DRWHP? (D is for Dynojet, so we don't get confused).

hacker-pschorr

That would be my guess.

My 81 put down 160rwhp SAE on a dynojet a long time ago with original cats and valve guides dripping oil into the combustion chamber.

This was before I knew about downloading the data file and that shop is long gone so I cannot do an over-lay. I'm not even sure where the print out is.

Mongo

The torque gain is unbelievable! 16 valves sure love that larger single pipe!