jbv

Hi All:

I'm retiring my carbed 305 in favor of a 350. I would like replace it with the GM Goodwrench 350. I'm curious as to why the GM Goodwrench 350 from SDPC is rated at 249 hp/304 ft lbs, and the exact same same engine from Jegs w/ same cam and heads etc., is rated at 260 hp/355 ft lbs.? What am I missing? Any input would be appreciated.

TX: JBV

ede

could be anything, it's not really a big differance. exhaust, timing, air temp all play a part in HP ratings, and they could of rounded off their numbers.

357mag

GM rates the goodwrench 350 at 260 hp with a four barrel carb and headers.

Tim sends

jbv

357mag:

So am I right in saying the lower rating of 249 hp/304 ft. lbs. is rated maybe with a 2bbl carb and cast manifolds as opposed to a 4 bbl carb and headers?

jbv

357mag

jbv,
That sounds right to me. My figures actually came from the summer 2002 Pace Performance catalog, not GM. Sorry. As of the catalog date, the Universal 350 was priced at $1449.00, plus freight. They also have a package deal with serpentine pulley system, water pump, ps pump and alt, Edelbrock fuel system (600 cfm 4 bbl, Performer intake, mech fuel pump), HEI, plugs, etc, ad nauseum... All in all sounds like a smokin' deal for 3 grand.
Tim sends

RB83L69

That motor, when it came in vehicles, was rated at 165 HP with a 2-barrel carb and exhaust manifolds; and 180 HP with a 4-barrel. I personally can't imagine how you could ever get 249 HP out of those particular parts, let alone 260. That just seems like a pipe dream to me.

I would expect no more than 215-220 out of it in a typical car install with headers. Maybe people who own it and have had their cars dyno'ed can post the numbers it gave. I'd expect to see #s in the 170-180 HP range at the wheels, with headers and a typical budget 4-barrel (Edelbrock Performer, Holley 0-1850, etc.)

Ray87Z

CHP did a big buildup/dyno flog on the Goodwrench a couple years ago.

Stock with "a stock aluminum intake" (same as L69 305 HO manifold I guess, beats me) and a qjet, with cast iron exhaust manifolds with dual 2 1/4" exhaust it made 239hp and 324 ft-lbs.

With headers added it made 255hp and 349 ft-lbs.

With a standard Performer intake it made 265hp and 350 ft-lbs. Now you figure just a bit less power actually in car vs a engine dyno and you still get somewhere right around the 250-260hp it's commonly advertised as.

Pretty good IMO considering the really small cam. Not bad for $1200ish that they go for, new 4 bolt block, PM LT1/LT4 connecting rods, nodular crank, all new parts not rebuilt...


Further on with a intentionally light pocket porting job on the heads (to be easily reproducable for the do-it-yourselfer they say) and a backcut on the exhaust valves it made 280hp and 361 ft-lbs.

Last up with a CompCams XE268 cam thrown in it got up to 336hp and 377 ft-lbs. Would have been nice to see what it did with just the cam swap and the stock heads though, around 290-300hp I'd figure, not bad at all...

They went on to swap on Aluminum L98 heads (355hp with light porting and Performer RPM intake), Vortec heads (371 hp straight on, 384 hp with light porting, and 408 hp after alot of tweaking, etc), and Trickflow 23 degree heads (416hp untouched) to test different combinations. Even tried a Weiand miniblower with the TFS heads too (471hp). Over 100 dyno flogs all in all they said, with no sign of trouble from the Goodwrench...

RB83L69

I don't believe for one minute that by the time you get that motor into a car, it will perform any different than it did in the 70s; it's the same parts. 70s smogger 993 heads, 929 cam, dished pistons, the whole thing, is identical by part #s to some of the 165-180 HP wonders of the 70s.

The people who have installed them and then complained about how slow it is would probably agree.

Ray87Z

Yeah you know how dyno numbers lie everytime... I don't know what the old engines really did, but this one does better now it would seem...

CHP wasn't the only mag to do some testing on the motor in the last few years. All got around the rated power numbers with headers... Accounting for engine dyno vs in-car setup power differences you should still get numbers pretty close to the rated power unless you believe these numbers were somehow inflated to the tune of 50hp consistently... GMs not really in the habit of doing that on their crate engines...

jbv

Yes, I agree:

I think we have to remember these engines are tested under ideal circumstances, on a test stand, in a controlled environment, by pro's who can tune an engine to the nth degree, to get the numbers they want. After installing into a car, bogging the engine down with all the pollution control equipment, and sending it all through cast manifolds, I can see why their is such a big difference.

jbv

Ray87Z

Here's another set of dyno numbers, I think these were from a CarCraft article series, but I don't have it noted:

Goodwrench 350 -
Q-Jet, LG4 intake, stock cam, cast iron exhaust manifolds -
230 hp - 320 ft-lbs

Performer intake & headers -
258 hp - 331 ft-lbs

218/228 – 112 cam -
309 hp - 354 ft-lbs


And I don't know how "tuned to the nth degree" these results are, on the first dyno numbers from my first post above which I have the whole articles series for there were no timing or carb changes made during any of the bolt on tests to the Goodwrench after the baseline when it was merely setup with the Qjet and 34 degrees total timing. Don't know about in the dynos in this post, I don't have the whole article, just these at a glance results... Exactly how hard is it to tune such a tame, stockish motor??? Not that hard... Yeah you'll lose some power when you stab it incar and hook up the rest of the accessories but not to the tune of 80hp (I'm talking about in car with the Performer intake and some 1 5/8" headers typical for our thirdgens)... I would be interested to see what a Performer RPM in place of the Performer would do as well.

Damon

Remember that their crate motor rating assumes more spark advance, a much better exhaust and a slightly better intake than the factory smogger rating from the 70s.

The old LM-1 350 engine was rated as high as 195 HP from the facotory with an emissions spark curve, stock manifolds, single exhaust, restrictive 70-s era "bed-style" catalytic converter and a cast iron intake.

Relieved of these restrictions I can beleive the motor would make around 250HP.

I have used this crate motor several times to replace old worn out 305 emissions-era engines. In every case it felt like we strapped a second engine under the hood vs. the stock motor. It's HP rating is not total BS, in my opinion.