360 on the dyno

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Babyblue66

Babyblue66

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I built this for a lady's 71 Duster. Her old 360 was a turd. She also requested it "sounds good".
8.8 to 1 using speed pro H405CP pistons
2.02 1.60 stainless valves
Stock replacement rockers, shafts, and pushrods
J heads with a little pocket porting
Hughes 2336 Whiplash cam
Performer intake
Recurved old Mopar Performance distributor
Milodon windage tray
9 keyway timing chain degreed per cam card
With my 750 Holley HP it made
353 hp
388 ft lbs
Using her 600 Edelbrock it lost about 10hp and torque.
Ignore that little curve at the beginning of the pull. It has something to do with loading the dyno.

20220421_131905.jpg


20220421_131858.jpg
 
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Nice lil 360 & should still have plenty of vac for power brakes. Interesting cam... wondering about this from the spec:

Our Whiplash cam is designed for basically stock, low compression engines. This cam will run on pump gas in a 340/360 with 8.6:1 or less compression and iron heads. If your compression is higher than this you may need to use a higher octane race fuel. Your vacuum should be in the 9"-11" range using this cam.
Click to expand...

If you had bumped the CR to 9.5:1 do you think you'd have detonation issues on pump gas?
 
I think it had 11" of vacuum. I'm not sure if it would ping with 9.5 compression. I wanted it to be pretty basic and no chance of that happening.
 
Babyblue66 said:
The performer RPM was backordered so she bought the wimpy one. It would've made 1hp per cubic inch.
Click to expand...
Or may be an Air Gap. It will still be a nice streeter and another 10 horsepower would barely be noticeable. Any videos?
 
Why are the left and right bank AFRs so drastically different? Was there a problem with the dyno sensors?
 
74Scooter said:
Nice lil 360 & should still have plenty of vac for power brakes. Interesting cam... wondering about this from the

If you had bumped the CR to 9.5:1 do you think you'd have detonation issues on pump gas?
Click to expand...
Bare minimum vacuum for power brakes is 16", they may not work the best
 
Babyblue66 said:
I built this for a lady's 71 Duster. Her old 360 was a turd. She also requested it "sounds good".
8.8 to 1 using speed pro H405CP pistons
2.02 1.60 stainless valves
Stock replacement rockers, shafts, and pushrods
J heads with a little pocket porting
Hughes 2336 Whiplash cam
Performer intake
Recurved old Mopar Performance distributor
With my 750 Holley HP it made
353 hp
388 ft lbs
Using her 600 Edelbrock it lost about 10hp and torque.
Ignore that little curve at the beginning of the pull. It has something to do with loading the dyno.

View attachment 1715912413

View attachment 1715912414
Click to expand...
Good power and torque
 
Babyblue66 said:
I think it had 11" of vacuum. I'm not sure if it would ping with 9.5 compression. I wanted it to be pretty basic and no chance of that happening.
Click to expand...
You're smart. No need for over 9:1 on pump gas. This sounds like a build that will likely see 87 octane all its life. No need to crowd it. Good job.
 
I'm really,really starting to like the Hughes whiplash cam. It simply works!
very nice combo, should make for a great street cruiser.
 
People who suck up what all the magazines and forum gurus say simply don't understand what it takes to make an engine run with no trouble whatsoever from detonation. I'll give a good example.

In 1972, compression ratios were dropped across the board. Even the high performance engines were advertised at "only" 9:1 or a "little" more. I'll give the Chevy LT1350 as an example. It was rated in 72 at 9.3:1, yet they all came with a sticker in the window that said "THIS VEHICLE REQUIRES PREMIUM FUEL". Premium fuel in 1972 was between 98-101 octane and it was LEADED. The factories knew that even at "only" 9:1 or so, these engines would still see difficulty idling in traffic in stop and go situations, see heat soak and detonate.

Can it be done? Of course it can. There are iron head builds over 11:1, but they are costly with added machine work and very close tolerances. It ain't cheap to do on most "budget" builds. Chambers have to be exact. Deck heights have to be perfect and even. Valves need to be all perfect on the seat and at the same level.

IMO, a lot of these guys boasting about high compression on pump gas are simply flat out liars. Just because a magazine says you can do it, or some forum guru says he has 11:1 and revs his junkbox to 7K on a regular basis, doesn't make it true.

Don't buy into the bullshit. You'll regret it.
 
RustyRatRod said:
People who suck up what all the magazines and forum gurus say simply don't understand what it takes to make an engine run with no trouble whatsoever from detonation. I'll give a good example.

In 1972, compression ratios were dropped across the board. Even the high performance engines were advertised at "only" 9:1 or a "little" more. I'll give the Chevy LT1350 as an example. It was rated in 72 at 9.3:1, yet they all came with a sticker in the window that said "THIS VEHICLE REQUIRES PREMIUM FUEL". Premium fuel in 1972 was between 98-101 octane and it was LEADED. The factories knew that even at "only" 9:1 or so, these engines would still see difficulty idling in traffic in stop and go situations, see heat soak and detonate.

Can it be done? Of course it can. There are iron head builds over 11:1, but they are costly with added machine work and very close tolerances. It ain't cheap to do on most "budget" builds. Chambers have to be exact. Deck heights have to be perfect and even. Valves need to be all perfect on the seat and at the same level.

IMO, a lot of these guys boasting about high compression on pump gas are simply flat out liars. Just because a magazine says you can do it, or some forum guru says he has 11:1 and revs his junkbox to 7K on a regular basis, doesn't make it true.

Don't buy into the bullshit. You'll regret it.
Click to expand...
I remember too well my 351C Ford, built in the 70s, 11:1 compression, 4V iron factory heads, big cam, etc. Ran like a scalded cat on a cool day, but always on the edge of detonation and usually at 200-210*, even in cooler weather. Helluva lotta fun though, when it wasn't eating transmissions at least.
 
It really doesn't take much to build a strong engine. Just the right combination and a little porting. Thanks for all of the positive feedback.
 
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