Real World HP & Torque [Archive] - El Camino Central Forum : Chevrolet El Camino Forums

: Real World HP & Torque

Mama Mayhem
10-20-2006, 01:07 PM
Can somebody in the know give me a real world estimate on my horsepower and torque numbers for my set-up and planned changes? Here's what I already have:
Block casting # 14093638, translates to '87-'95 5.7/350, 155-255 hp
Head casting# 14102191, translates to '87'95 350, 1.84 int./1.50exh.
Engine was rebuilt stock (pistons, etc),except for the following:
Summit K-1104 cam and lifter kit (specs):
RPM range 2200-5200
Duration @ .050 224int/224exh
Advertised duration 282int/282 exh
Valve lift w/factory ratio 0.465int/0.465exh

Edlebrock Performer manifold
Holley 650cfm spreadbore, vac secondaries
Hedman 1 5/8" primary full length headers into full length duals with MagnaFlow mufflers w/ H-pipe located between headers and mufflers.

Plan on changing cam to the following:
Summit K-1105 cam and lifter kit (specs):
RPM range 2200-5700
Duration @ .050 224int/234exh
Advertised duration 282int/292exh
Valve lift w/factory ratio 0.465int/0.488exh

Full roller rockers 1.5 ratio

I know this is not any kind of KILLER motor but I like it, just curious about what kind of numbers it's producing and will likely produce with the cam and rocker change.

10-20-2006, 01:51 PM
It is always difficult to guesstimate horsepower but I would guess that it is on the south side of 300hp. The camshaft you have is already too big for the heads and compression that you have, why do you want to install an even more agressive cam?

10-20-2006, 03:02 PM
Dunno about the cost or availability in your neck of the woods, but for less than $100 I can get a pull on a chassis dyno and find out with reasonable accuracy what my HP is (now that's "real world"). Anything else is an educated guess.

Example: Friend at work added Edelbrock Performer RPM Heads and air-gap manifold and a Demon annular venturi carb to his 454 in a 66 Vette 4 speed. Before he went, I'd have bet his HP was over 400 out of the box. Testing showed it was barely over 300. The cause of the low output was 3-fold: Carb was super lean because the jetting was way off, the timing was way off and the exhaust was too restrictive. Though it ended up costing him about $300, just changing the jets and the timing improved HP output by 25%. That's not free HP, but darn close to it.

Moral of the story? Get it tested so you know for sure and listen to the recommendations of the dyno experts who do this stuff for a living. I'll beti in your case they won't recommend you beef up the cam.



10-20-2006, 03:32 PM
A dyno pull around here is $40 each with a minimum of 2 pulls, of course that's for rear wheel HP numbers. You will also get an accurate air/fuel ratio printed on the dyno sheet. I found mine was running a tad rich when the secondaries opened. I made some jetting changes and went back to the dyno and gained 20HP.

Also, if you know your cars exact weight and get an ET at the track you can compute your HP fairly accurate.

This one gave me 10 RWHP more than the dyno recorded.

10-20-2006, 03:35 PM
I agree with Mrapii. What you have for heads are 87 centerbolt truck heads that have 1.94"/1.50" valves not 1.84" These heads produce good low end RPM torque because of their swirl port design, (pulling power for a truck) but in your case they're a limiting factor because of both the swirl port design and valve size. You need a better set of centerbolt heads (if you want to keep your current intake) or a better set of the older style heads with 2.02" intake valves 1.60" exhaust with an intake designed for the perimeter bolt valve cover style heads or modify your current intake (not all that hard). You could also switch to Vortec heads which will require a different intake altogether because of the raised ports. Going to a bigger cam is not going to do all that much for you if. You could almost attain as much lift by going to 1.6 roller rockers as going to that Summit cam, but you would still need to remove the heads to enlarge (drill) the pushrod guide holes if you did go to 1.6 rockers. I know we're talking some money here, but a set of Edelbrock Centerbolt heads #60859 would really wake your motor up, not that Summit cam. Roller Rockers would be icing on the cake...but if I was to replace the cam, it would be a hyd roller cam since that block you have should have the retainer (spyder) plate bosses cast into the block.

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Mama Mayhem
10-20-2006, 03:42 PM
I wish I knew where a dyno was in my area, I'd go there for real readings. However by "real world" I mean somebody that has experience figuring this stuff out fairly close by the numbers, yes a guesstimate but a fairly close guesstimate that some people are good at (I'm not), not some wingnut saying I'm pushing 4 or 5 hundred hp and 750 lb/ft of torque (I know better than that).
I agree with Mrapii that I'm somewhere south of 300hp, as I was thinking somewhere north of 200hp, but I believe there are some here that could calculate a little closer estimate.
As far as the cam, the K-1104 was already installed in the engine when I bought the car. I was thinking about the K-1105 because of the higher lift on the exhaust side, which from everything I've studied, should help with the breathing on these stock heads (which I know are not real good heads, performance wise).
However if this is to aggressive a cam, there are these possibilities also:
Summit K-1103
RPM range 2000-4000
Advertised duration 272int/282exh
Duration @ .050 214int/224exh
Lift 0.442int/0.465ext
Lobe seperation 112degrees


Summit K-1102
RPM range Idle-5500
Advertised duration 262int/272exh
Duration @ .050 204int/214/exh
Lift 0.420int/0.442exh
Lobe seperation 112 degrees

Car is street driven daily and 1/4 mile on Friday nights. So I'm looking for my best street/strip combo with what I have. By the way I'm looking more at torque to get this beast down the 1/4 than hp.

10-20-2006, 05:28 PM
I used a weight of 3800 as a guess for your elkys weight. I plugged in the ET and speed you've posted and came up with 197.8 RWHP based on ET and 218.4 RWHP based on speed. That would be for the combo you had when you made that run. I think those numbers are good if your elky weighs what I suspect. Drivetrain loss is generally figured at 20%-25% so that gives you about 262 HP at the flywheel as an average.

With that info some may be able to speculate what different mods may do for you.

Mama Mayhem
10-20-2006, 05:47 PM
After rereading John Lingenfelter's book, I might very well go with the Summit K-1102 cam as it is still a dual pattern cam that has higher lift on the exhaust side, but is alot closer to his recommenations on the breathing capabilities of these heads.
Yep, I could buy new heads and all, but I'm just looking for minor inexpensive improvements in what I already have. Summit cam kit $70, roller cam at least $400. Summit 1.5 roller rockers about $220, Summit 1.6 roller rockers same price plus tall valve covers and clearancing the push rod holes.
I got the 1.84 intake valve size from parts ID, Mortec didn't show the valve size.
I'm being cheap (I know) but like I said I'm just trying to improve a bit on what I already have. Maybe someday I'll spend the money to build a bad***** 383 or even a 421 smallblock :roll: , but the purpose of this thread is to see if anyone can give an educated guess as to what kind of power and torque I'm producing now and with the cam change.

Mama Mayhem
10-20-2006, 05:50 PM
Thanks, BigJames :hail2:

10-21-2006, 01:41 AM
I played around on the DT Dyno and you engine is around 270hp at the flywheel. I then changed out a few cams too. I would leave the Summit cams at summit and buy a comp cam or another big name manufacturer. Both Comp cams 260 and 268 showed huge improvement over the cam you are running now. The Summit cams have a wide lobe seperation, hence losing too much cylinder pressure. the Crane power max 290h was a good one too! My friend ran theis cam in a `69 chev 1/2 ton with the original 350,performer int., stock Q-jet, ram horns, 3.08 gears and he ran a 15.30 in the quarter.

10-21-2006, 07:11 AM
How about a Lunati Voodoo cam? Take a look at pn 60103 and 60104.

10-21-2006, 02:17 PM
those are too big for your heads.Comp 262 Xtrem energy would be better.

10-21-2006, 04:10 PM
weight is closer to 4000 lbs

Mama Mayhem
10-21-2006, 04:24 PM
That comp xtreme 262 is close to what I already have from what I see.
Does your DT Dyno do torque figures also or just hp? I'm thinking about getting one.
When Mrappii brought up about already having an aggressive cam and going more aggressive, it got me to thinking, so I reread my book and saw that on the heads I'm running 0.420 lift is about max for how these heads flow. So it got me to thinking I might actually improve by going to a smaller cam, that's why I put in the specs on the Summit K-1102 and K-1103 cams.

10-29-2006, 06:02 AM
Trying to optimize performance by matching the cam to your current heads is clearly the right thing to do.

Cranking the options list up a notch, I was going back through some previous Chevy High Perf magazines and saw an article you might benefit from. It's Aug 06 issue, page 22, called "Power Curves". They tested 8 diff SBC cyl heads, all but one of which were at/below $1000. If you can spring for a few extra bucks, getting a modern matched cam/head/intake combo will be a substantial performance gain over trying to optimize flow in your current heads.

Just a thought.

10-30-2006, 08:18 AM
Mama you can see some improvement on 1.6 Rockers for your intake Valves and 1.5 or stock rockers on the Exhaust side. Small intake valves gain when adding a little larger lift/duration and you could keep the cam you have now. In essences your changing the lift of the cam by changing the Rocker Ratio.

Read an article some time back on some Chevy Mag and they did that and got about an additional 20 Hp just by changing to 1.6 intake rockers. Remove the Clutch fan and you'll gain back about 10 to 15 HP you loose pushing that mechanical fan, assuming you have a mechanical fan. Add an electric Water Pump and you've gained about 10 more HP (roughly). Add it all up and there could be as much as 40 possibly 50 Hp gain. Not shabby and you didn't have to pull a cam.

Just a thought.

I believe you will eventually need better heads.

10-30-2006, 09:06 AM
If the heads can't flow the lift he has now, higher ratio rocker arms won't do him any good.
the torque was;

365@3000 and 3500

this cam is different in many ways from the cam you're running! For one it is a quality cam, two, it has 6 degrees less duration than the one you're running, Three, tighter lobe seperation,four, different lobe design.
If you think it is the basically what you,re running then run the cheap crap.


10-30-2006, 12:14 PM
If the heads can't flow the lift he has now, higher ratio rocker arms won't do him any good.
the torque was;

365@3000 and 3500

this cam is different in many ways from the cam you're running! For one it is a quality cam, two, it has 6 degrees less duration than the one you're running, Three, tighter lobe seperation,four, different lobe design.
If you think it is the basically what you,re running then run the cheap crap.


And how do you know what Cam I'm running, cheap or not?

Mama Mayhem
10-30-2006, 02:14 PM
Well guys I appreciate all the suggestions and all, but like I said I'm just playing around wih the motor and heads I've already got, just tweaking on it. Maybe someday I'll buy some better heads, but then I'll build a motor to match. The engine I have came in the car as decribed and I'm not putting any serious money into it (this is fun to me). As far as the quality of the parts, I have never had any problem with Summit brand parts as they are usually made by the major manufacturers for Summit and cost alot less than the name brand, some things I won't use anything but name brand ( ie: only genuine Cummins parts go into my big truck motor), but for playing around with different flat tappet cam profiles I can buy a couple different Summit kits at the same or less cost than one name brand cam and lifter kit. Once I find a profile I'm happy with then I can swap in a name brand with the same profile, if I so desire