[gtofreek]

I recently finished machining, and building a .065" over 400 for a 67 GTO street car. You can read about the build here.
http://forums.maxperformanceinc.com/...d.php?t=785341

OK, so we get 'er dynoed today. I was pleasantly surprised. Here is how it was dynoed.

1. Points distributor with Blue Streak points.
2. Cliff built 1967[I believe] Q-jet. 6.5 lbs. fuel pressure[was 5.7 lbs. but somehow crept up to 6.5].
3. Stock 1971 iron intake. Unported, as cast.
4. Crappy 3 tube Cyclone headers, no mufflers, w/ 6" diameter pipe slipped over collector to vent exhaust outside.
5. 91 octane pump gas.

Just to refresh, this is a 413", 10.1:1 compression, 67 GTO engine. It has CNC ported 670 heads from Dave @ SD Performance. RPM 5140 rods, and CP flat top .065" over pistons, with Steel gas nitride top ring, Napier second ring, and low tension oil ring. Stock crank, .010"/.010". The cam is a Lunati VooDoo hydraulic roller, 231°/239° @ .050". Ground on a 110" LSA. Install on a 103.25 ICL. Lifters are Hylift/Johnson.

First off, we hit the button, and it fired up within 2 seconds. Instantly idled, but just a tad low so I set it up to around 850-900 RPM. Engine had a steady 60 PSI oil pressure. Set total timing at 36° BTDC, not knowing what these heads would want after the mods Dave did to the chambers. Heard no audible detonation. Plugs looked good. I predicted about a week ago that it would make 453 HP, and 482 ft. lbs. of torque. First pull it made 447 HP, and 484 ft. lbs.! Bumped the timing up to 38°. It made 456 HP and 494 ft. lbs. Still heard no detonation, and plugs looked good, with no visual signs of detonation, and looked to be burning about right[not too rich, not too lean], so we bumped the timing up to 40°. It made 465 HP, and 503 Ft. Lbs.! Look at the torque down at 1500 RPM! 400 Ft. Lbs. @ 1500 RPM! 500 Ft. Lbs. @ 2900-3000 RPM! For a pump gas 400, this thing is a torque monster!

Here is the dyno sheets. The guy finally got new ink cartridge so now the sheets are dark enough I can scan them and still read them.





And a graph.

[PAUL K]

Nice!

[92GTA]

Damn that thing is a low end torque beast, awesome!

['ol Pinion head]

Impressive!

[gtofreek]

That's a Harold cam for ya!. Also, Dave did a nice job on those heads.

[Tom Vaught]

Your street car will be very happy with that engine.
Assuming a 3800# vehicle with driver and a good tire, you should be able to run very low 11s even at Tucson. Maybe even a 10 second time with your 413 engine if the weight is wrong and the night air is decent.

Tom V.

[gtofreek]

Thanks Tom! I think he'll be real happy with it too!. I think if he were to get his intake ported to match these heads, it ought to be right up near 500 HP then.

[gtofreek]

Here is a video of it idling at around 850-900 RPM.

https://www.youtube.com/watch?v=PXdN...ature=youtu.be

Here is with 38° total timing. Listen closely, and you can here the lifters reach their RPM limit right at 6000 RPM.

https://www.youtube.com/watch?v=H5ct...ature=youtu.be

Here is with 40° total timing.

https://www.youtube.com/watch?v=6kWe...ature=youtu.be

Here is the last video. This is where he pulls it backwards to get numbers way down low. It is wide open throttle here, and he just keeps applying the water brake to slow it down. Notice how well mannered it is at 1300 RPM wide open.

https://www.youtube.com/watch?v=guWe...ature=youtu.be

[Half-Inch Stud]

Real nice combo!


shoulda kept them 3-tube headers! Do round-port 3-tube headers exist?!

[Steve C.]

Very nice.

Stated- "Listen closely, and you can here the lifters reach their RPM limit right at 6000 RPM."

Would you mind sharing the valvespring package in use with some specs.

Which springs, installed height, measured seat pressure, etc.

Thanks.



.

[gtofreek]

Springs made 160-165 #'s on the seat, and 385-400 open.

[chiphead]

Wow, wow wow. You have my attention. Brace yourself, questions are coming. I have yet to read the original thread, so forgive me if some of this stuff is there.

Were the chambers opened up on the 670s? Do you have flow sheets? How much vacuum at idle? Why a 110 LSA? What plugs? Why low tension oil rings on a street motor?

This sort of shows what I found with my 670s, they wanted more timing than you would think. My motor ran best at 36-38* NA at 9:1. You would think that a compact chamber would require less timing, but the stock shape must really hurt flame travel.

How would this cam behave in a 9.2:1 400 with 6.8 rods?

[steve25]

CNC porting got the the heads flowing about 250 to 260@28"?

[vidguy]

Yes
.500 = 257.7
.600 = 262.2
@28.0
Porting done by, and chambers opened to 80cc, Dave at SD

[gtofreek]

Originally Posted by chiphead

Wow, wow wow. You have my attention. Brace yourself, questions are coming. I have yet to read the original thread, so forgive me if some of this stuff is there.

Were the chambers opened up on the 670s? Do you have flow sheets? How much vacuum at idle? Why a 110 LSA? What plugs? Why low tension oil rings on a street motor?

This sort of shows what I found with my 670s, they wanted more timing than you would think. My motor ran best at 36-38* NA at 9:1. You would think that a compact chamber would require less timing, but the stock shape must really hurt flame travel.

How would this cam behave in a 9.2:1 400 with 6.8 rods?

Dave at SD Performance did the heads. The chambers were opened some. There are flow sheets posted in the thread about his engine. You can find it here.

http://forums.maxperformanceinc.com/...d.php?t=785341

Didn't think to get a vacuum reading.
Why not a 110 LSA? This is a short stroke engine. These Voodoo cams have such broad power bands, they don't need to be put on a 112°. They make more power on a 110. I think the stock, un-ported intake was the limiting factor here. I feel that is why it peaked at only 5400. Every pull peaked at 5400, no matter what we did. I think a ported intake will help this a bunch.

We used NGK plugs, heat range 8.

The ring pack is a modern metric ring pack[1.5mmx1.5mmx3mm]. It is what came standard with these CP pistons we got for it. It utilizes a Napier second ring which is a great oil control ring, so you don't need a high tension oil ring for them to control oil. Different story with a regular, taper face ring. Total rotating force needed to rotate completely assembled shortblock with rope seal = 17 ft. lbs. to break free, and 13-14 ft. lbs. to keep rotating. Compare that to about 35 Ft. Lbs. for a factory stock ring pack shortblock assembly.

9.2:1 is a little on the low end for this cam. Really need 9.5:1 or better if using it in a 400. In a 428 or 455, it would be fine at 9.2:1.

[gtofreek]

I was just noticing that at 1800 RPM this engine basically matched the torque of a RAIV engine at 3600 RPM! At 1/2 the RPM! That's pretty amazing.

[pontibeast]

Paul that is one hell of a nice Pontiac. I just picked up my engine from the builder/machinist and with it being a 455 I will be really down if it doesn't have a little more grunt but I have to wait to get to the dyno. Great work and I am looking forward to some burnout videos showing up on you tube soon.

[gtofreek]

I just did the math, and from 2700-5500 RPM, this thing made an average of 487 FT. LBS.!

[mgarblik]

Those dyno sheets show why Pontiac engines worked so well on the street. Nice street manners, tons of torque. Done making power at 5400 RPM. Torque down from peak 150 ft. lbs. @ 6000 RPM. No need to ever run it there. Running 5400-5500 RPM, it would be a great street engine. No exotic parts needed, should last forever. It made that power at almost 200 degrees water temp to. Nice engine.

[gtofreek]

Yeah, and the oil temp gauge wasn't hooked up so that number is just the ambient room temp.