Tim Murphy

This past weekend I dyno'd an 87 auto and 81 5spd to get baseline HP numbers before supercharging them.
The 87 auto made about 260HP 270TQ.
The 81 5spd made about 160HP and I'm not sure what the TQ was. (I don't have the sheet).

While there, I put my car on the dyno and made 2 runs and they were both within a couple HP of each other. I'm running what appeared to be about 12.5 psi boost. The air/fuel ratio was super rich below 4K rpm and then straightened out upstairs. As a result I made less HP at 4K than I have in the past even though I made 25 more peak HP. I modified the fuel system to give me more fuel and that is why the HP went up slightly. The plan for this car is to run 16psi boost but until I get total control of the air/fuel I am going to leave it where it is. The drivability of the car is really nice and without the charts you wouldn't know the air/fuel was off at all. I'm waiting on some hardware that will allow me to re-map the fuel tables. Anyway, here's the sheet.

bcdavis

AWESOME!

Tony

<Best surfer voice>

Duuuuuuuuuuude



Is this the low CR motor?
Looking forward to the after of the other two, especially the 81spd

PorKen

640 crank HP! Jeepers!
...

Are the baseline cars stock, and in good tune?

My '81 automatic consistently pulls 20-30 more RWHP on DynoJet.

BrianG

That's 500+ hp at the wheels??

Tim Murphy

The compresson is about 8.7:1 with all stock internals.

Tim Murphy

The 87 auto only has 39k miles so it sat around quite a bit. Every now and then it runs pretty rough and then straightens out again. I think it just needs to be run for a while to make it happy again.

The 81 sure sounds like it runs right. The fuel system was all gone through so it should be okay. Shoving some air through that little "barn door" should really wake this thing up. We'll know soon enough as to wether or not I will continue with the 16 valve cars.

bd0nalds0n

I'm almost embarassed to ask, but do these cars get the same kind of mileage as NA cars, if you can resist the temptation to get your foot in it, or does raising the fuel pressure and using higher pressure injectors automatically translate into poorer economy even when driving conservatively?

Tim Murphy

11mpg hot rodding (most likely worse but that is the ave)
20mpg hwy

Gretch

Yep, those are my numbers too, 12mpg with lead foot, 19 without........

That ain't bad though....I remember a 427/435 corvette a friend of mine had that got an av MPG of 8.........

Jim R.

Tim,
That is some serious power! I can't let my car see those graphs, or it will be asking for more power.


Jim R.

Shane

That will put a smile on your face!!!

stuartph

Guys


12mpg for lead foot driving and 19mpg for the highway aint bad at all with that amount of BHP


Stuart

GT UK

hacker-pschorr

I'm pretty sure my car is in good tune. You've seen my other posts about my motor, and the work I've done to it. Pull was made in 4th gear.

1. CR is within range
2. New plugs (Bosch copper)
3. Rebuilt injectors
4. All new vacuum lines, coolant lines...etc.
5. Air pump removed
6. Charcoal vapor system removed (per your directions)
7. Cooling fan removed - electric installed from Murph's kit

160 rwhp did strike me as low, 27% drivetrain loss is a bit extreem. Only thing I can think of at this point is my car does run a bit rich per my cabin mounted gauge. I'll give a more accurate reading of this once I get home in case that is more of an issue.

Porken - what CR is your car at?

My vacuum/boost gauge is at 20psi when the throttle is closed, 0psi when WOT.

I'll post the sheet in about 2 hours.

Kaz

That's great mileage, put your foot into a 2003 E55 and you'll be lucky to see 8mpg.