SU's Dyno, triples Dyno

[LeonV]

Guess we'll have to go bit-by-bit here...

Leon,

The thought was along the lines of pinging is a lean condition so more fuel eliminates pinging and gets a mixture ratio more in an acceleration range or 12.5-13.5.

"Pinging" (engine knock) happens for a variety of reasons. It has nothing to do with what carbs you're running, as long as they are tuned properly for the engine.

The larger displacement of the 2.8 requires more air which is easier to accomplish thru three dcoe type carbs than two single bore carbs without raising velocities a lot higher.

Right, that's what I meant in the pumping losses bit of my previous post. You said nothing about air in the post I quoted...

It seems triples tend to run some what rich and at the DCOE Yahoo group that is the way they suggest running them.

This is backwards. Triple carbs with individual runners should be able to run leaner than their multi-runner-per-carb counterparts, simply because of better mixture distribution (also part of my previous post). The 40s on my L24 idle at 14.5:1 and I'm shooting for a cruise mixture of at least 15:1. That alone debunks the "triples tend to run some what (sic) rich" propaganda.

Lastly gasoline is being converted to power, so to make a lot of power it takes more fuel. That is why even new cars with crazy amounts of power with modern systems don't get fabulous fuel mileage because the engine needs a certain amount of fuel. Just my deductions...

Charles

An engine needs spark, fuel, and air to run. Spark is easily provided and controlled, as is fuel. The tricky part is getting as much air into the cylinder as possible. In other words, the maximum power you can achieve depends not on how much fuel you can dump into the cylinder, but how much air you can get in there so that the fuel you dump in can actually burn. You can't burn the gas if you don't have the air to do so!

When replacing SUs with triples, the engine is able to ingest more AIR due to decreased pumping losses, better manifold design, and stronger resonance effect. THIS is why triples can increase power. It's definitely not because they like to run richer.

As for modern high-powered cars not getting good gas mileage, I call baloney. Is 505hp and 30+ mpg not good enough for you?

Edited September 13, 2013 by LeonV

[Travel'n Man]

A larger venturi and increased porting could help achieve that 200+hp.

[Reverend]

Hope you can dyno your car soon! I wonder how much power increase comes from Triples (sk) and header alone...thats all i have..(not installed yet)

[jmortensen]

Just my $.02, a "mild" cam isn't going to give the best results with triples. I went with a .490/280 cam and wished I had gone bigger. When I put the triples on my Z, my wife was afraid to drive it because it had so much more power. I would guess ~40 whp by the butt dyno. It was SIGNIFICANT. I believe Dan Baldwin documented 50 whp on his motor here some years back.

[grannyknot]

Those are better than reasonable numbers- those are excellent numbers. I have read too many threads where folks have gone the stroker route and didn't do this good. Looking like 200+ HP at the rear wheels with triples is very possible . That is an accomplishment to be proud of- congrats.

Where were you at with the timing and what ignition ?

Steve, the stock L24 single points distributor with a Pertronixs ignition module that I'm using was set at 10* static for the dyno, but I was just catching up on posts and found this, http://www.classiczcars.com/forums/electrical-s30/34192-280zx-distributor-advance-curve-reference.html have a look at post #19, Walter Moore's research might mean I have the wrong static timing. I'll have to check the stamped code on the side of my dizzy.

It is a good dyno result and the best part is it was done on a Dyno Dynamics roller, they are known as the "heartbreaker" because they always display lower or as the guy who bought the dyno says, "real" numbers.

Hope you can dyno your car soon! I wonder how much power increase comes from Triples (sk) and header alone...thats all i have..(not installed yet)

Sooner the better for me as our weather is starting to cool a bit. Just waiting for this SK float level sight tool from japan, just want to make sure everything is properly setup before I take it for tuning and then the dyno.

Just my $.02, a "mild" cam isn't going to give the best results with triples. I went with a .490/280 cam and wished I had gone bigger. When I put the triples on my Z, my wife was afraid to drive it because it had so much more power. I would guess ~40 whp by the butt dyno. It was SIGNIFICANT. I believe Dan Baldwin documented 50 whp on his motor here some years back.

Jim, the engine came with the mild cam and I wouldn't want to change it out until I have the carbs running perfectly

and then only if I find the cam to be the limiting factor. But I have to say I love that flat torque curve, everything it has to offer is available at low rpm right up to red line. This is a weekend street/highway car.

Chris

[siteunseen]

I'm not understanding the colors on the chart, very neat by the way Mr Moore. I've got a D6K8-22, vacuum advance 30 and 57 total advance. It's in the RED section. Is that bad? Should I get one that's in the YELLOW? I'm installing it in a '77 2.8 FI with N42 Head. Thanks for thread, I thought all E12-80's were the same.

OK I just saw that the RED was higher and maybe harmful to my motors health.

Edited September 15, 2013 by siteunseen

[Walter Moore]

I have never taken my car to a dyno, so I don't know what HP it has. For reference on the spark knock, I have modified the S120 distributor on my car to restrict the vacuum advance to 17 degrees. The setup is 10 static, 17 centrifugal, and 17 vacuum. This takes me to 44 degrees total advance at around 3k rpm when the vacuum advance is engaged. (Generally only in 5th on the interstate at light throttle.) I have to run 93 octane gas or else I get spark knock.

You can confirm your total advance with a "dial-back" timing light. I bought one at NAPA and it is a really great tool. Using one you can discover all kinds of things about the timing curve of your distributor.

[siteunseen]

Thank you, I learn something new everyday on classiczcars.com.