More power in this combo???

la360 · Post by **la360** » Sat Jan 01, 2005 9:46 pm

Is there more power in this engine? It is a fairly basic 360 chrysler engine, it made 495HP@ 6300, and 471ft/lbs@ 4800(std/cr). The engine specs out as follows-
Factory Block 4.04" bore ARP head & main studs
Factory J heads 2.02"/1.60" Manlet Pro Flow valves
Head flow @25" -
0.100" IN 62.5 EX 48.5
0.200" IN 131. EX 95.5
0.300" IN 173.5 EX 123.5
0.400" IN 222.5 EX 139.5
0.450" IN 235. EX 145.
0.500" IN 238. EX 147.
0.550" EX 152.
0.600" EX 153.
0.650" EX 156.
0.700" EX 158.

Compression Ratio 11.4:1 static 150psi cranking Around 185 BMEP

Mechanical Camshaft 0.590"/0.598" w/1.6 Rockers
255/263 Dur@ 0.050"
104.5 intake centerline
108 Lobe separation
0.015"/0.020" Lash
Profile originally was designed around a 104 Lobe separation. Unfortunately I don't have the duration @0.200", only the catologue valve timing & ramp heights.

Edelbrock Air Gap intake
Mighty Demon 825 carb
HVH 2" Super Sucker Spacer

Custom headers 1 3/4" x 32" primary
3" collectors with cone in center 12" overall length

MSD 6AL CDI ignition, Modified Bosch Distibutor , MSD Blaster 2 Coil

The was dynoed with a pair of collector extensions that were around 12" long, The guy that made our headers had trouble listening to instructions, as I asked for the primary lengths to be 36" with a 12" collector, and as you can see, that's not what I got. Adding length to the primaries is the first change I will be making, and fitting the collector extensions for when the car is raced again.

The car was raced just the once, without the extensions it was dynoed with, with very marginal traction, to a best of 11.47@117mph, with 60ft times of 1.7-2.0's. The rear end is in the process of being redone for a larger tyre now, so traction won't be an issue. The car was also a little under geared, which has been changed also.

Where could I look for more power? i honestly didn't research the camshaft all that much, I chose this one because I felt it should keep the peak power under 6500rpm, and bleed off a little cylinder pressure at low engine speeds so it could be run on Pump gas if need be. We didn't flog the engine much on the Dyno, 7 pulls in total, as it made good power from the start (481 HP std/cr)
Any help is apreciated
AL...

la360 · Post by **la360** » Mon Jan 03, 2005 11:53 pm

No one has any thoughts? Or would you like to know more?
AL...

Speedy Goomba · Post by **Speedy Goomba** » Tue Jan 04, 2005 12:06 am

Al,
what tire are you using now?

how much MPH are you picking up from the 1/8 to the 1/4.

Post all the incrementals on that best pass, along with Density Altitude information if you have it.

Speedy Goomba · Post by **Speedy Goomba** » Tue Jan 04, 2005 12:19 am

It's my opinion, but i think you are pushing it with Pump gas and that compression.

So you're making the compromise and chose larger duration specs then would be optimal for that power range. For what you're doing i think 6-8 degrees less on both the intake and exhaust would be closer to optimal, along with a tighter LSA.

However i do think that the intake choice is a good one, and the headers are nearly perfect.

The optimal engine combo for this car revolves around the chassis (weight, ect) as well information on what gears were used on that pass, and what converter.

la360 · Post by **la360** » Tue Jan 04, 2005 1:35 am

We race the car on 100 octane fuel, just wanted to have the option of running pump gas on the street. When we raced it, we were running a 26x8.5" slick, running around 92-95mph at the 1/8, and 115-117mph at the quarter. We are fitting up a set of 29/11-15 Hoosier slick now, and geared the car up some.
The car has an 8" 4800 Stall convertor, that flashes around 4800-5000 from memory. I share the car with a friend, and hence the driving, but we bothing drive in similar manners, which is good. I was shifting it at 6500, and crossing the line at around 6400-6500. This is with the affore mentioned tyre, and a 4.11:1 gear. The Hoosier tyre that is replacing these little things is around 29.5 in dia, and I would like to see a little more RPM across the line. We have a 4.71:1 center to go in now, along with a set of 35 spine Mark Williams axles. The convertor showed about 5% of slippage, so with that I would expect to see 6800rpm over the line at 120mph. I am going to look at a Auto Meter Ultimate II tacho, so my info can be a little more accurate.
AL...

la360 · Post by **la360** » Tue Jan 04, 2005 1:42 am

That is what I was thinking in regards to the camshaft, we have being playing with this basic combination for a little while, trying different things in different engines. Obviously what we did here isn't optimal, and I went with a 108 lobe separtion to err on the safe side, I may look at changining the camshaft later down the track, something with similar duration @ 0.200" , but less @0.050", on a 106 . We dynoed a friends engine, that is very similar, almost identical in fact. He is running less compression, around 10:1 I believe, with a shorter camshaft, and 1.6/1,5 rockers, and tri Y headers. He was down 10 HP on what we made, and about 15 ft/lbs. That made me think there is more in this engine, plus I would now like to see more pressure cranking. Thanks for taking the time to reply Speedy.
AL...

Gary 540 · Post by **Gary 540** » Sat Jan 15, 2005 4:58 am

We have pretty good pump fuel in Australia, with a motor octane of around 93 and a research of 98.
I think it could do with a full point more compression, get the cranking up near or above 200.
I mainly build chevs, but always spec em out for around 200 + cranking pressure.
Latest example 3100 lbs car 12.7 compression, 260 - 260 106 lsa .550 .550 single pattern solid flat tappet. 220 cranking pressure.
Premium pump gas, thru full exhaust 10.03 @ 135 mph

70MC · Post by **70MC** » Sat Jan 15, 2005 12:30 pm

Gary 540 that sounds very impressive, how many cubic inches is that engine?

I have 11.7 compression in my 434sbc, 268-278 @.050 110 lsa solid roller, and my cranking pressure is 220. I run pump gas only, with timing 36* it ran about the best, tried 38* ran the same et., tried 40* and i heard it ping when i left the starting line and it ran the same et., but i was 1mph faster in the 1/8 and down 1mph in the 1/4 with 40*, i have my timing locked out. Thats with full exhaust and 93 octane, 3900lbs, 10.84 @124mph.

Gary it seems as though your cranking compression would be higher with 12.7:1 and a smaller cam, comparing to my combo, what am i missing?

Gary 540 · Post by **Gary 540** » Sat Jan 15, 2005 5:59 pm

Hi 70MC it is a 406 Chev, pair 23 deg racer pros, milled down, pistons stick out of bores .011" run a .041" felpro, quench is .030", 6" scat rod, flat top piston, super victor intake, 975 4150 series holley. Holley programable ignition, timing @ 34 locked. We used to always run on av gas but one weekend backed it down and tried Optimax, left exhaust on as it was backed down, this is a street car. Gold hatchback, and we ran 3 x 10.0s at calder.
This thing has a leakdown of 3-4 % and a genuine 215 -220 cranking pressure, all plugs out, and big battery. Makes high 500 s in horsepower.

la360 · Post by **la360** » Sat Jan 15, 2005 7:23 pm

I thought I would mention for our American friends, The 98 octane fuel here in Australia, is like your 92 octane fuel. I think we use the RON octane rating over here, and you guys use the MON, it could be the other way around, can't remember exactly. All I know is that our system measures and list the fuels peak octane, and not the average octane .
A 383 Holden stroker that was built at my friends shop was dynoed on SHell 100 fuel, and then on Mobil Synergy 8000 pump fuel, 627hP on the Shell 100, 613 on the Mobil Synergy. I think from memory they took about 5 or 6 degrees of total timing out of it. My friends dyno has a Motec Knock sensor which is quite sensitive, which has proved quite helpful on alot of the pump gas engines he has done lately.
Anyway, we have a few things still to try with this engine before it comes out late in this year, we have a W2 headed Chrysler engine that should be finished in the coming months to go in. I will most likefully try the header extensions the engine was dynoed with first, and then try adding to the primary lengths once we can get the car to 60ft in a decent fashion.
Thanks for the replies so far, Gary, keep an eye out for a white VG Valiant coupe with Centerline Convo Pros.
Thanks all
AL...

Gary 540 · Post by **Gary 540** » Sat Jan 15, 2005 7:58 pm

Seen it, nice car, think it has black vinal roof.
Aprox 15x8" on rear 15x5" on front if its the car Im thinking of, very clean car too ??

la360 · Post by **la360** » Sat Jan 15, 2005 8:36 pm

The Convo Pro's are a new addition, we are fitting a set of 15x10's into it now. It's all white, and would have had Weld Superlites on it first, and then a set of black 15" ford wheels. Haven't been out to Calder in a while, so I haven't seen the Hatchback you're talking about, I am assuming it's a LX Torana? Do you have a shop somewhere in Melbourne Gary?
AL....

lugnut5 · Post by **lugnut5** » Tue Jan 25, 2005 10:12 pm

You may be able to get some more cranking psi. by backing off the exhaust lash. With the overlap, it will close the exhaust valve sooner, therefore sealing the pressure sooner , giving you more cyl. press. Just a thought, it worked for me though.

Lugnt