1978 308 GTS Dyno results

doesn't look like anything changed from a stock car. assuming 15% driveline loss, 205 hp == ~175 RWHP. if i'm reading it right, that's disappointing given all those changes.

john

 

Interesting compared to my slightly hotter than stock 246.

approx 200 RWHP, stock US claimed 175 I think, Euro's were 190

What were the factory specs for the 308 GTS that year?

DM
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oh ok, i hadn't seen the earlier results. so you've gained 11 RWHP. not bad! seems worth it. what are you using for a muffler? i don't want to spend the money on a tubi/ansa.

john

 

Actually, he's gained about 70 HP from his first dyno run. Seems healthy for a 78, remember they only were rated at 205

 

That is very healthy for a USA '78. Also keep in mind this is nearly a 30 year old car. Who knows what the compression looks like etc. Keep in mind that no two dynos are the same and some are more optimistic than others.

At our last dyno day, the best 308 was Verell's Euro QV which did 190 RWHP IIRC. Considering that the Euro QV was rated at 240 and the USA '78 carb was rated at 205, I would only expect about 165 from the '78.

Now I really want to get mine back on the dyno.

Birdman

 

Seems like you've made good progress, but, if you're going to run sans air pump, you might consider removing the air injection nozzles (which partial block the exhaust port) and the air injection manifolds (which get "cooked" long-term) if they are still present. Try a search on "air injection nozzles" -- should get you most of the prior discussion.

 

That stock '79 graph looks familiar, hmmmm.

As you can see, I had some high-RPM "issues" back then, hopefully I have solved them, plus lots others. I'm eager to get it back on Aaron's dyno to see.

 

A VERY healthy 78, considering the years - especially if no recent valve job.
I raided my dyno library to find some you might be interested in for comparison, three rear wheel dyno charts and an engine dyno from the Carobu website. The rear wheel chassis dynos are for a 308 qv (not well, I believe) and two 328s. The direct engine dyno is from a freshly rebuilt, tweaked and optimized Euro 308 GT4. If you calculate the rear wheel hp on the Euro GT4 ( multiply by .83), the rear wheel hp/torque should be 194.8/168.2 approximately. I have a lot of dynos on the Mondial from development, but not really applicable here.
To me the torque numbers are the most interesting.
best
rt
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There is no horse power in these things at lower RPM's. After seeing the Dynos, I now understand why my 85 dosen't get out of it's own way. I usually shift at 3000+ and seldon shift past 3500. I guess I need to quit driving it like my 4 liter Jeep Wrangler.

Now I need to know how to take off faster from a standing start. I prefer to let the clutch out quickly at low RPM's (save the clutch) and not to slip the clutch at higher RPM's

Doug

 

or add a blower

When my QV was stock, my autocross start consisted or bringing the engine to 5500 then side-stepping the clutch while slamming the throttle to the floor. It goes pretty well that way. With the modified engioen it's all about low rpm and not having too much throttle....3000rpm and 2/3's throttle in 2nd gear seems about right. I'm adding traction and launch control this winter, that should make good starts easier to replicate.

 

You slip the tires...not the clutch.

They are easier to change!

 

You have to take it to 8,000 RPM sometimes to clean the carbon off the valves....it looks like a fireworks sparkler, when done at night.....

 

OUCH!!!! Man, I'm getting the shakes just thinking of that! How well does the clutch and drivetrain hold up to that kind of abuse?

Birdman

 

Thats why you buy an american muscle car,
and the parts are cheaper when you bust'em,

I did a 7000 rpm side step in a 440 6pack cuda once. Uncontrolable tire spin, and there is probably still gummy 2 holes in the pavement.

 

Yeah! It's one of the great things about these cars. Taking "care" of them is so much fun!

 

440's come on cam with the starter motor and make peak power at 5200 RPM, they are head limited past that. SHIFT!!! I have broken body welds on my GTX Convertable catching second hard, shifting at 5500 RPM (twice).

The Ferrari is quite another matter, I don't get into it untill over 3500 RPM. I haven't taken it past 7000 RPM since I don't trust my 13 year old cam belts even though they look new. I know, I know, I have new belts in the garage and will change them in a few weeks, as soon as I get the interior back in the GTX.

Both cars have Borg & Beck clutches but the GTX's is a little bigger and has a three finger pressure plate. Clutch disks are actually more expensive for the GTX though. I always wondered why Ferrari used diaphram pressure plates.

(Sorry if I strayed from the original thread.)

 

I've posted before, but I recall my 78 308 GTS ran about 178hp on the dyno. This was a 30k+ mile car, with recent major service, new factory plug wires, Crane Cams XR700 ignition, cat bypass pipes, no air pump belt, 135 main jets, K&N air filter, stock air box and stock muffler.

 

Sounds like the wrong answer on a 440 6pack cuda...but a 5500 side step is what it takes to launch a stock qv.

 

I did 20-30 of those without a problem before I torn it apart to add the 1st blower. I have a different clutch now, but its the same everything else in the driveline.

 

Russ, that dyno for the GT4 dont look right. Power is falling off far to soon. And look at the torque curve, its dowhill far to early. Seems that peak power should have been up closer to 7K and not fallen off so dramatically until much higher. Yet it still made almost 235 HP. Not bad. I wonder what my 77 would do?

 

I know what you are talking about and I agree, but it is right off the Carobu website - I would bet it is quite accurate and that engine was VERY VERY tweaked (Tate's personal car featured in a Forza article). You know, I have noticed that MANY 308/328 actually peak the power a little lower than claimed around 6500 or so instead of the often claimed 7000.
Interesting.

I would bet your 77 would do quite well.
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