Boy am I bummed out...terrible dyno results

[jeff1216]

All this work that I have done to my 78 280 and what do I get....Terrible dyno results

Mod List

The car already had a F54 block and flat top pistons

I added

E88 heads...ported and polished over sized valves heavy springs

Arizona intake

Stage III cam

New Holley 390

Today I added a 2.5 inch exhaust flowmaster and a brand new dizzy and module for a 80 280.

I am smoking at high RPM...Blue smoke...I guess I need new rings....I guess I lost alot of HP there.

Dyno results

115 HP to the rear wheels

145 foot pounds of torque.

I am bummed....all this work and money for such a shitty result.

[seerex]

I think there is an issue somewhere there, you got me worried as well , I have planned a simliar motor except an e-31 and su carbs , hope you get it back up to snuff

[ZmeFly]

I know your bummed but your biggest mistake with your set up was going with the Holley carb and Arizona intake.

The Z wasnt meant to be used with a downdraft carb. It was meant to be used with side draft carbs.

Sell your intake and carb, and get yourself a clean set of su's or a set from Z therapy. Go back to the dyno once you have those and your rings done, see the difference.

there is a 12 sec na dual su carbed Z and hes in your area. That should give you a little hope.

Maybe not, Im not sure if its North or South Carolina that he lives in.

[Zedrally]

Yep!

At least you finally got it going, but if you're looking for better performance, SU's or EFI, unless you're willing to look at triple's

[2ManyZs]

I was going to say the same thing....

I don't know that it's the fault of the carb, it could be the intake manifold itself. It's difficult to get the same amount of fuel/air mix into the cylinders when all the runners of the intake are different lengths and 2 of them are at least twice the length of number 3&4....

I'd be willing to bet, with a set of decent SU's, you'd see a big difference. And, with your mods, a set from ZTherapy with larger needles would let you maximize your mods you have now.

[Zvoiture]

Shoulda left it FI....145 at the rear wheels and it runs. Always.

steve77

[Gav240z]

I'm looking into a FI kit using a webber manifold that way I get six throttle boddies the mods will be very similar to your motor and I will be using a 76 degree camshaft.

I am hoping to extract 180 rwhp or 130rwkw. Either that or stick with the SU's and see what comes of that.:classic:

[280zx Fever]

All that work....and it actually has less hp then a stock 280z does...

a stocko l28 in the 280z puts out around 125rhp

As others have said these cars are made for side drafts..because of the angle of the ports

Triple 50mm webbers might be the go choke them down a little

[SteveK]

Hi jeff1216

Yep theres definitely something amiss there

I (last week) spent a day on the rolling road (dyno I guess you lot call it)

With a stock L24 bottom end, mildly worked Samuri top end, stock cam and valves sizes, tubular header, K&N's and SM needles in stock 240 SU's we got in excess of 120 at the wheels

The guy who owns the rolling road is well versed in Zeds and recently spent a week comparing a set of stock SU's with a set of triple webbers and could only get a marginal improvement, Datsun did a very good job of matching those SU's to those heads (well OK all except for those pants flat tops).

Yep triples look great but for simplicity, reliability and guaranteed results the SU takes some beating and as someone mentioned will take you into some fairly good HP territory)

PS if you go to SU's use the SM needle, gave great mixture linearity and didnt need touching at all (the guy at the rolling road grinds most of his needles)

[Daniel]

I do not say this to hurt you, but just as this is something that we all learn about Z cars. Its damn hard to beat those that designed it. If you think you are sure you are going to "out clever" them you better think again real hard.

[280zx Fever]

Originally posted by SteveK

Yep triples look great but for simplicity, reliability and guaranteed results the SU takes some beating and as someone mentioned will take you into some fairly good HP territory)

for a stockish engine i suspose SU's are the go but imo webbers would be better suited to a mild-heavy worked engine then SU's...just imo.

[ZmeFly]

Its kind of hard to argue with a motor that does the 1/4 in 12 seconds on SU'S!!!

Webers or triple anything isnt always the answer.