Anybody put a V-6 on a dyno?

[Mike Caldwell]

I got to wondering what the "modern" numbers on torque would be from one of our Big Block V-6's after reading about what some of the new V-8's were putting out.

I know EFI, variable cam timing, etc etc can all help make power but I'd love to have some numbers that I had more confidence in while planning my project.

[GVDobler]

I thought I read on Jolly's site that the HP and torque were around 200.

It would be interesting to see a curve on the torque. Maybe just a flat line from idle to 3,000 RPM. Haha

[Corts60]

I plan on putting my TBI 351 on a dyno after the build is complete.

[GMC-HDV6]

The GMC V6 websites engine data page lists the power in both gross and net power. So you have the "old" and "new-modern" power numbers ;)

I have seen a GMC 379 V6 dumped up to an 8.6:1 compression ratio lay down 175hp@3,400rpm / 388tq@1,600rpm on a dyno print out.

I myself have thought about combining the 4.25" bore of the 305s with the 3.86" stroke of the 379/478s and having a small but torquey GMC V6. Say 328-ish cubes ?

Mike

[bigblockv6]

Stroking the 305 is a waste of time and money,the 379,432 and 478 crank is externally balanced and has an 8 bolt mateing pattern to the flywheel.You would need all the attaching parts to it like the front balancer and flywheel out of a 379 or 432 V6 from a 73-74 6000-6500 series truck. These parts are not an easy find but that's just half the problem. You will also need a custom set of pistons to match the longer stroke at roughly $1200 for a set or more. It's much more cost effective to just drop in a 351 or 401 V6.

[GMC-HDV6]

Well apparently you haven't tried to rebuild a 351+ V6 before the 4.56" and larger pistons all have to be custom made. Lots of piston options for 4.25" bores. Sounds like either way to go your dealing with "custom made parts" ;)

Now when you figure in diesels are large torque engines most designed with a larger stroke NOT larger bore ! I also feel my idea will net a much better power to weight ratio once completed.
Have to get custom pistons anyway so may as well increase the compression say 9.5:1 instead of 7.5 or 7.8:1 . . . Sorry if I wanted "cost effective" I would put a modern small block in it.

None the less its off topic here so I shall discontinue the conversation here and start a new one.
Mike

[bigblockv6]

Well Mike,apparently you do not know very much about the GMC V6 engines! I have rebuilt a 478M with OEM .030 oversize pistons, have a personal stock of oversize 351, 401 and 478 piston sets and to top it off I've been tinkering with these engines for nearly 40 years. Talking about weight there would be a minimal weight difference between a stroked 305 vs a stock 351 in light duty pickup truck applications making it insignificant. Pete Chronis Northern Cal. 68 KM-2500 478M V6

[Funky61]

Got this graph from a GMC Data book. This is for the 305C. It also had the same for the 379, 432, 478.

[Funky61]

The 379

[Funky61]

432

[Funky61]

478 Magnum

[Funky61]

DH 478 Turbium

[Funky61]

last one DH478 Turbium

[GVDobler]

Looks like my my flat line remark was close to the truth, at least on the torque. I don't recall seeing another engine that flat.

Thanks for posting.

[Mike Caldwell]

for "how flat" reference

454 chevy dyno

http://i253.photobucket.com/albums/hh78/Mike_Caldwell49/454dyno.jpg

478 graph cleaned up a little in photoshop

http://i253.photobucket.com/albums/hh78/Mike_Caldwell49/GMCdyno.jpg

[GMC-HDV6]

Looks like the 454 is the way to go, Nice straight steady power as where the 478 has a rather sharp incline on the HP numbers than just ends ? ! ?

Torque on both don't seem to fluctuate much as far as the line goes visually speaking.

Unless I'm missing something ? ! ? Please do explain if I am ;)
Mike

[Mike Caldwell]

check the axis -- graphs are not on same scale. I tried to read chart on 478 to get some numbers to graph vs 454 but eyes went crossed and I've got to go get some work done.

Also note that 454 wasn't graphed until 3500, when 478 graph stops about there.

As always it's low-end grunt vs top end hp.

I LIKE TORQUE

[GMC-HDV6]

I wasn't watching RPM's I was just simply watch how flat the line was left to right.

With gear ratios like 5.13, 5.38, 6.17, and so fourth a top end puller would work great for road speed on the highway ;)

I got a GMC V6, 4spd, and 5.13s or 5.38s even with 19.5s its only does 58-62.5mph at 3,000rpms.
245/70R19.5's = 58mph@3K-Rpm and 8-19.5s = 62.5mph@3K-Rpms :eek: GPS'd it even.

Its a mean truck off the line but once it rolling in 4th gear its all done, It'll tow a lot behind it though and have no issues.

Drop 18-22K-Lbs on the hitch and roll it down the road.
Mike