dynoing my brother's 340

[95teetee]

went with my brother yesterday while he was getting his engine dynoed- it's a 340, fairly mild- cammed up a bit, Edelbrock single-plane mani, 650 Holley, forged everything, with h-beam rods. This is basically the initial startup and first few tuning runs, still a ways to go.

the reason for the cast iron exhaust manifolds is that the engine's being built for a turbo setup- so it's also only 9:1 instead of the stock 10.5:1.

here is the comparison of a couple pulls- just trying different jets out- both about 315 peak torque and 270-275 HP (stock rating was 275 horse). We also tried an 800 edelbrock carb, but that didn't really change anything- it's not running short on fuel...


kept dropping off top-end because as the tuner, Greg, put it "it's constipated".

Greg talked my bro into putting headers on it, despite the fact that he didn't want to because of the impending turbo...


here's a comparison of headers to manifolds-


from 295 ft/lbs and 274 HP to 343/318.

I thought this was the car he's building it for, turns out it's one of his other barracudas- same idea though...the calculations put the setup @ about 12.6 in the quarter with the 31X horsepower number

[R154]

very nice numbers with that low compression. NA cars tend to suffer here in calgary so I would be surprised if you saw a solid 150 HP over with a big turbo on high boost.

any more info on the setup? fuel delivery? is itr staying carbed, or are you going to do an efi setup?

[chkolny541]

are you saying 12.6 w/ or w/o the turbo? and what psi are you going to set it at, and have you weighed that car before? looks heavy

[JRSC00LUDE]

Ahhhh the 340, best small block to come out of the muscle car era imo.

[95teetee]

Originally posted by R154
very nice numbers with that low compression. NA cars tend to suffer here in calgary so I would be surprised if you saw a solid 150 HP over with a big turbo on high boost.

any more info on the setup? fuel delivery? is itr staying carbed, or are you going to do an efi setup?

he's planning on sticking with the holley- apparently the kit has an under-carb setup to pull the A/F through, rather than push it in. I don't know much about the kit he bought unfortunately, and haven't dealt with adding boost to NA cars at all...especially carburated cars...

Originally posted by chkolny541
are you saying 12.6 w/ or w/o the turbo? and what psi are you going to set it at, and have you weighed that car before? looks heavy

the 12.6 was for the numbers with the headers (318 horse)-the car weighs 3100 lbs. Not sure how accurate the tuner's numbers are, but he's heavily experienced with his racing, so I don't doubt him generally . Of course, there are variables in the drivetrain losses that were guessed at though...
He's planning on going wastegate pressure- I was telling him about the benifits of boost controllers, but haven't convinced him yet

Originally posted by JRSC00LUDE
Ahhhh the 340, best small block to come out of the muscle car era imo.

agreed- I had a '72 Duster with a transplanted-in 340- 11:1, 2.02 heads, hi-rise edelbrock with 780 holley, etc. 340 with huge cam @ idle=

when (if) he gets close to adding the turbo, I'll try to get some more info and see if anyone here has any advice on the setup. But, this motor's running so nice the way it is, I think he's toying with the idea of adding the turbo to the 416 stroker he's building next. Or my yellow car. One or the other