Dyno Results

[goingballistic]

First off thanks to all the people on this board that helped me get this motor to the point it's at, without your help ( and you know who you are) this would have been a lot more painful.
My won and I started this project two years ago, so it's a long time coming. Started with a old 350 block from a '74 Nova and built from the ground up.
Two days of testing on the dyno, painful but I would recommend a dyno test for anyone who builds from the ground up to work the kinks out before installation.
Problems encountered during the test:
1) Fuel flow was too small with an Edelbrock 750 CFM Carb, ended up with a Demon. Edelbrock has a convulated air flow through the secondaries and starved the horse power. 750 Demon got me where I wanted to be as there is no restrictions in air flow through the throats.
2) Roller rockers needed to be torqued to 1/2 turn tight NOT a 1/4 turn tight to set the rockers correctly, one poped, we caught it before it did any damage.
3) Two piece timing covers are crap, don't use them. ****ed three quarts of oil out the front, had to change to a one piecem worked fine after that. The two piece doesn't hold under vibration, don't use them.
4) Oil fliter needs to be tight.................ooyyyy. Oil pressure on the 10th run dropped to 2PSI my blood pressure went the other way, thank god we caught this one before we did any damage. If this was not on the dyno, it would have blown the motor.

All in all it was a great way to break in, money well spent and saved my engine. Ready for drop in now, headers on back order, wish I would have had them before the dyno but couldn't wait any longer. The headers we tested with were only 1 3/8, engine is spec'd for 1 7/8 so I expect a little more power with the right headers.

Final results: 425HP with 472 ft lbs of torque ! Yikes...........now I need a new diff ratio............my wife is gonna kill me...

Pic of the motor on the dyno.......

Link to us doing the rebuild

http://www.supermotors.org/vehicles/registry/detail.php?id=5167&s=17984#content

Cheers.

 

[Jack]

Congrats
Would be nice if you showed comprehensive list of motor parts: heads, cam, lifters, rods, pistons, crank, intake, carb, bore size, block decked, heads milled, head gasket .... etc. A copy of both dyno graph & table would be cool too.
Jack:gap

 

[kiwi vet]

A wise man

Well done!!! and congradulations on the new engine, you must be very happy with that!

I couldnt agree with you more on the dyno run in procedure, have had a few engines done this way and all results were always great, and in the long run can be less expensive and definately less stressful.

I think its only common sense to spend a few hundred dollars to protect and monitor the few thousand we just spent on the engine.

Again, well done and goodluck

Grant

 

[goingballistic]

Congrats
Would be nice if you showed comprehensive list of motor parts: heads, cam, lifters, rods, pistons, crank, intake, carb, bore size, block decked, heads milled, head gasket .... etc. A copy of both dyno graph & table would be cool too.
Jack:gap

Good point leave it to Jack to make it

Block was decked to zero
Bored 60 over
Internal Balance Scat crank ( 350/383)
Comp Cam 12-250-3 .507 intake .510 exhaust Flat Tappet
Hydraulic lifters
SRP -4 dished
6" rods
1.6 roller rockers
AFR 195 standard port, springs and valves
Edelbrock RPM AirGap intake
Demon 850 carb ( 750 would have been fine but didn't have one during dyno, so I opted for the 850 to keep going)
MSD HEI Distributor
TCI Rattler balancer ( internal )
Milidon 7 qt pan

Heads were not milled, standard AFR. Head gasket is spec'd by AFR, I can get that if you want it. The dyno sheets and torque curves are hard copied, I can photograph them and post if you really want them, shows a dramatic difference between where we started and where we finished.
All in all I'm pretty satisfied with the results, would have liked more HP but I think this enough to rough up and road kill some rice burners

 

[Evolution1980]

What was the final cost of entire test & tune session(s)?

 

[goingballistic]

What was the final cost of entire test & tune session(s)?

The actual Dyno time was $500 including the tune, they charged me for an entire day but actually spent more than 10 hours on the setup. Estimated time was set at 4 hours but due to the problems we encountered, it took more time than anticipated.

BTW I love that paint job !

 

[Evolution1980]

The actual Dyno time was $500 including the tune, they charged me for an entire day but actually spent more than 10 hours on the setup. Estimated time was set at 4 hours but due to the problems we encountered, it took more time than anticipated.

BTW I love that paint job !

Do you do this prior to breaking in the engine? Or is this more or less considered the engine break in? Or doesn't it matter?

(Thx for the compliment on the paint. in person, it's starting to show it's age but I still like it. )

 

[goingballistic]

Several reasons to do this, major one is to break it in and the other is to find and fix problems before it goes in the car. After spending close to $8K on this motor, I didn't want to chance something coming apart in the car. The oil leaks alone saved me because the dyno allows an emergency shutdown so once we saw the leak ti was about a second before the engine dropped to zero rpm's, in the car I never would have seen it until it was too late, so for me it was money well spent.

The guys who did the dyno test said they have seen lots of people build them but not dyno them and run into my type of issues after installation and usually results in a fried motor. Keep in mind I am not a mechanic, this was a project that my son and I started but the engineer in me said "test it" to see if what I designed really did what it was supposed to and my confidence level was not what I would call 100% to just drop it in...............and the threat of my castration from my wife :L really had me worried, we're dropping it in tonight. Waiting for the headers before I can restart and run it.

 

[Evolution1980]

Do you have your trans rebuilt to handle this new power? Or, more generally, has the car been setup to handle this increased power? Cooling, suspension, transmission, driveline, etc...

 

[Jack]

Nice looking combo!

AFR's have what size cc chambers? What fuel (octane) used for dyno? race gas, pump hitest?

 

[goingballistic]

Jack: The heads are 74 cc, I didn't want the CR too high so I could stay on pump gas( CR is about 10.3:1 ). The gas we used during dyno was 93 octane.............I didn't build it for gas milage . There's a private airport about a block from my house and I know the guy who owns it, I've been helping him with his rebuild. He is in the process of building a vette up as well and offered me his gas AND his runway to test this when it's done..............I can't wait.

Evolution: No, no other mods have been done to handle it........one thing at a time. My plan is to up the back end ratio to about 3:25, beef up the drive shaft and have it balanced, new U joints etc, other than that nothing. It's a standard TH-350, I did install a new torque converter last night, 28-32 B&M 10" Hole shot. I think the tranny will distintegrate shortly, my long term plan is to drop a stick in it but other things such as paint and interior are going to take priority right now, now the engine done. The wife WANTS me to finish the car, so while she wants, I'm doing the expensive stuff

Engine went in last night, few hiccups, mainly the torque converter alignment, new motor mounts etc. My headers are on back order for another three weeks. One thing I did find last night that kind of freaked me out was that the tranny mount was sheared, ordered a new one today from MA. I'm damn glad I caught that last night or that tranny would have been sitting in my lap first time I got on the gas.

I also now need a new hood :eyerole the Demon carb/RPM Airgap setup is too high for the stock hood, I kind of knew that before starting but was hoping it wasn't true, I really wanted the car to stay as stock looking as possible. Road kill with a "stock" 81 would be "Priceless".........Oh well.

Cheers.

 

[Evolution1980]

Too bad ya just bought a new trans crossmember...Woulda sent my OEM for free!

I have the "OEM" with the raised cowl hood on my car. Stock looking, except just raised up an additional 2" or so to clear the aircleaner.

 

[goingballistic]

Evolution:

Can you tell me more about the hood. Was it stock and moded or did you buy it that way, if you bought it, where?

I only need 2 more inches or so won't know until I get the cleaner on but that looks about right with a drop base.

 

[Evolution1980]

Can you tell me more about the hood. Was it stock and moded or did you buy it that way, if you bought it, where?

I bought it that way from one of the regular vette places below. Here's what I found just looking around

Store ... Part Number ... Price
Ecklers ... 10420 ... $600
Corvette Central ... 143148 ... $679
MidAmerica ... 608-135 ... $700

 

[Evolution1980]

I only need 2 more inches or so won't know until I get the cleaner on but that looks about right with a drop base.

Here's a little trick for determining if you have enough hood clearance (if you aren't positive).

Take about 18" of aluminum foil and lightly wad it up into a ball just a bit smaller than your fist. Place it on top of your air-cleaner and set the hood down. Then gently press the hood down until it catches the hinges and snaps closed. Open it up again, take out the ball which should now resemble a small can in shape. It'll be flat on top & bottom. Measure the height and that's the clearance that you have left.

 

[goingballistic]

Great idea...................but there's no way the hood will even come close to closing with the Demon and the air Filter combo. Just the vertical ports on the Demon would punch holes in my hood if I slammed it hard enough.

I think I'm going to put it all together and run a straight edge across the engine compartment and measure the clearance needed, I can't think of any other way to do it. I've got a drop base air cleaner but I still think I need more than 2" more likely 3 or more, now that I've looked at it after some sleep!

Thanks for the links, I really appreciate the help.

 

[goingballistic]

Motors finally back in the car, clean up, linkage, radiator etc. Almost ready to rock

 

[goingballistic]

As requested a photo of the final dyno sheet ( Engine only) . I pushed 425Hp max with a fixed and locked distributor, lost some as you can see on the sheet, down to a respectible 422.8HP and 466.6 Torque...........I'm pretty happy with that.

 

[Evolution1980]

Did they mistake your A/F readings with compression ratings???

 

[goingballistic]

Good catch I was wondering if anyone was awake!

The A/F meter on the dyno computer wasn't working so they used an external gauge. If you look at the first post in this thread of the motor on the dyno, you can see a little black box in the center, at the top, just to the right of the air flow hose ( two wires hanging from it), that's the A/F meter, numbers escape me but I think it was somehwere in the 13-17 range, don't remember now.