Thread: HP and Torque question

Tweet

I've got a basically stock 350 from a 1971 G30 chassis motor home. The only changes from stock are a melling MTC-1 cam kit (Dur. I - 204 Ex - 214 @ .050" Lift I - .420 Ex - .443), an Edlebrock Performer RPM intake, Edlebrock 600 CFM Carb, and a stock HEI ignition. I put this together a couple years ago before I really had any idea what worked with what. I know now that the cam and manifold are a little mismatched, I'll fix that later. My question is can someone run this on a desktop dyno and let me know approximately what HP and Torque it should be putting out. It's a 4 bolt block with a th350 transmission, '68 camaro eaton posi rear axle with 3.08 gears pushing a 3050# coupe with me in it.

I'd like to say that this forum and others like it are a wealth of information. I'm used to just trying things til I find something that works. Now with these forums, I've found out that in the past I've made a lot of mistakes putting these engines together and never knew it. I can see that at times I've spent a lot of time and money that was basically wasted. Thanks to these forums and the people on them that are willing to share their knowledge and experience, that won't happen again.

Thanks alot

Gary

can you tell me the LSA & also are you running headers or stock manifolds

I'm running block hugger headers and I'm not real sure what the
LSA means, but the lobe center deg. is I - 107 Ex 117.

What does LSA stand for?
I reckon I haven't read enough on here yet.
It's amazing how little I actually know about this stuff, considering I've worked on my own vehicles for the last 40 years. It's never to late to learn.

Gary

This question is of great interest to me since I am about to put an MTC-1 cam into a 350 for a fiberglass 29 roadster, estimated at 2500 pounds. Although I will be using a Performer intake instead of a Performer RPM and an old Q-jet carb (initially) with a 2.79 rear gear, I am interested to learn what average mileage you get with the TH350 trans and this engine and so far I have not been able to compare notes with many other users of the MTC-1 cam. As you say this forum is a great way to learn without the longer and more expensive path of actually trying various parts combinations. Another thing I wonder about the MTC-1 cam is that I have compared it to about ten other cams for low rpm torque applications (high ratio rear gear) and the MTC-1 has by far the longest total adv. duration along with specifications at 0.005 lift that look very conservative and like the Comp Cam XE250. Does this mean that the MTC-1 has softer lobe ramps and is easier on the valve train or that the 280 exhaust duration is an attempt at allowing some high rpm performance. I have talked to the Melling Tech person but he would only quote the numbers and not design criteria. It would be nice, and answer your question, if Melling would provide dyno charts as Comp Cams and Edelbrock do. Somebody must have run dyno tests at Melling when the MTC-1 was developed, is there anyway to dig out that data? I hope you can reply with your average mileage for your coupe (what model and year?) and any comment about bog or no bog in low gear with the 3.08 rear; I will be using a standard torque converter but with a heavy duty forged hub for towing a boat in the future. I envy you in that you have a running coupe while I am bogged down yet to run brake lines. Thanks for this question which surely must be of interest to many others.

Don Shillady

Don,

My coupe is an original 1929 Essex rumble seat coupe. I've had the car restored since 1987 but I just decided to rod it a couple years ago. As far as mileage, I have a mechanical AutoMeter speedometer and it's still not reading right. I just go with the flow in traffic. But, I would guess it at around 15 mpg right now. I just found out that my vacuum advance pod was leaking vacuum and wasn't working at all and the top screws on the carb were loose. I haven't driven it much since fixing these, but I expect the mileage to improve. I've got about 10k on the car since 'upgrading' it and I enjoy the hell out of it.

Check out my site at www.nucwa.com/page2.html
I have several pics of the car, just follow the link to the Coupe pages.

Gary

Gary,

Thanks for your reply, your car is very interesting and I am impressed by the fact that you did your own paint job! I guess 15 mpg for a 350/350 combination is about what I can expect. I am writing this time to ask about the PU radiator. The prices of some radiators are really high and I wonder if I change my hood to '30 Ford dimension with a '32 shell would the PU radiator fit since it apparently works to cool your 350? What are the height and width dimensions of the radiator, when you get a chance? I always liked the deuce shell anyway and it looks taller than the '29 so if I could get a cheaper radiator with the deuce shell that would be a good solution for me. Again, I wonder how you arrived at the selection of the MTC-1 cam. Apparently you are happy with that aspect of the drive train. I guess you have looked at the Comp Cam website with the dyno curves but I have noticed that while the MTC-1 duration at 0.005 lift is similar to several other torque/economy cams, the MTC-1 has much longer total duration. However, it seems to be working fine for you, thanks for the information.

Don Shillady

I played withthis combo in DD2000 I had to make a couple assumptions, but I come up with roughly 284 HP @ 4500 RPMs & 363 ft. lbs. @ 3500 RPMs. I put this engine in your 3050 lbs. Camaro & had to make a couple more assumptions but came up with 14.08 @ 100.1 MPH 1/4 mile times. not to bad really. That looks like the same cam as the Edelbrock Performer grind. John

Stepside,
Thanks, that's about what I figured, and the ET and MPH are pretty close. It ran in the 14s and low 90s mph. At the time I had a fuel pump going out on me and it was starving for fuel about at the 1/8 mile and just flattened out. The cam is pretty much the same as the Performer cam. I just went with it because it was available here locally when I was putting this thing together.

Again,
Thanks

Gary

Don,
The radiator is from a 1967 Ford F100 with a small 6 cyl. I cut the side mounts down to fit inside the shell and had the filler relocated so I could access it under the hood. I had it recored locally here with a 3 row Super Cooler (?). At least that's what the guy called it. I haven't had any cooling problems since I installed it. I'm using a 16 inch electric fan pulling air through it. I have a 160 deg. tstat and I've never seen it above 180. It normally stays around 150 to 165. I belive it cost less than $150 for the used radiator and having it recored. Of course the first thing I did was run a 1/4 inch drill through it while I was installing the fan mounts. The fan is mounted solid to the radiator side mounts, not with those squirrelly things that go through the core.
The core size is 18.5 in. by 18.5 in. Top to bottom including cans is 25 in.

The main reason I went with the MTC-1 is that I was building this as a daily driver and I didn't want anything too drastic. At 70 to 80 mph on the freeway it still has enough push to pass without going WOT. That's all I really wanted. I'm going in a different direction with the current project, 1993 Ford Ranger with 460/c6.
This one I want to go.

Gary,
Thanks for the radiator measurements, that option is good to know as I face the expense of a radiator. My hat is off to Stepside for the observation that the MTC-1 is close to or a knockoff of the Edelbrock Performer camshaft. I compared eleven towing/economy cams but did not see the match with the Edelbrock cam. At least that explains the longer duration of the MTC-1 (the duration at 0.006" lift). The good news is that with a Performer intake and the MTC-1 one has 2/3 of the Performer-Plus package and could envision a future upgrade of the heads to come close to realizing the 320 HP shown in the Edelbrock dyno sheet. While we are on the subject let me mention an article in a Hot Rod Annual from about 1968-70 entitled "Isky's Wailin' Chevy" in which there are many dyno tests of a 350. That article suckered me into wanting a 350 because they dyno-ed a stock engine out of the box at 293 HP and then got 62 more HP by only adding a 280 degree cam making it look like 1 HP/cube is very easy. Then I bought a 1976 Corvette engine to rebuild only to find it is only a two-bolt block and was rated at only 190 HP to begin with, while your 1971 block seems to have had better heads in stock form. I guess the lesson is that any 350 can be built for performance, but there is a wide variation in the stock form. You are fortunate to have one of the good ones.
I know I will wish for a coupe in the heat of July and the cold of February, but maybe the lighter weight of a roadster will pay off in the other months. If you need any reinforcement, I think you have greatly improved the value of your Essex with the 350/350 drive train.

Don Shillady

Don,
I don't know if you're aware of it or not, but the HP rating on the 76 engine is net HP. Taken at the trans tailshaft with all accessories installed. They changed the way the listed HP in '72 or '73. At the flywheel with a bare engine you can probably add 50 HP or more. From what I've read most of the 60s and early 70s were rated between 240 and 265 HP except for the high performance engines.
I've got to do a little work on the A/C. I've got a remote condensor on it and it doesn't really do a very good job. I need to mount it in front where it belongs. It cools, but not nearly as good as it should. Gonna need it in a few weeks.

Oh yeah,
Thanks for signing my guest book on my site.

Gary



This is a diagram of the radiator

Gary,

It is great to chat with you. I have to relearn a lot of stuff about modern rods. I am recently retired from a scholarly academic Chemistry environment and left U.S. street rodding around 1975, although I poured a ton of money into a dune buggy trying to make it perform like a Porsche S90 and then two tons of money restoring an MG midget. Along the way I missed some of the changes in U.S. engines. What you are saying now makes a lot of sense about the change in how the HP is reported. I checked

http://www.edelbrock.com/automotive/2102graph.html

and using that graph and the formula: HP = Tq x (rpm/5252) , I get a maximum HP of 279 at 4500 rpm assuming a torque of 326 ft. pound. Although that is for a Performer intake instead of the Performer RPM you have and I am assuming that the MTC-1 is indeed a knockoff of the Edelbrock cam, the picture of your engine on your webpage shows tubular headers as in the Edelbrock specifications so that value is very close to the 284 HP calculated above by Stepside454; indeed your Performer RPM intake probably favors higher rpm where HP is greater so again the 284 HP number Stepside454 estimated seems right on. May I say in a complimentary way that your kind of installation is more exciting to me than trailered show cars and I am glad to learn about the accessory A/C cooler since your practical installation (and reassurance of a lack of overheating) offers a way around the expense of some of the high buck radiators. Thanks for the diagram and measurement of the radiator, I will compare it to a Deuce shell and maybe that is the way to have a "cool-Deuce" front end, although I will probably go through a cut-and-try cycle as I proceed. I had dreamed of an esay way to get greater than 300 HP, but maybe 280 HP can still be a lot of fun.

Best Wishes,
Don Shillady

Great thread, you guys rock. I just dug out my records for an engine I had rebuilt in my 1971 vette back in 1988 and it has the same cam, an edelbrock performer manifold (circa 1988) and a brand new edelbrock performer 600 cfm carb on it. One question though, the stock horsepower for my corvette was listed at 290, but the figures you guys came up with were less, even with the mods. The only thing I can think of is that Chevy was listing flywheel horsepower and you guys are talking about rear wheel horsepower??? Anyway if you have time I would be great if you could run a horsepower simulation on my car. Let me know.

Thanks

Bombraz:

I do not have the software you need, but I can recap what I have learned from messages above. There are at least three (3) H.P. rating schemes:

1. Bare engine, no generator just water pump. This is probably what you are used to and what I read in the early article about the Isky-280H cam.

2. Engine with generator and transmission, H.P. measured at the tail shaft. This is apparently what GM changed to in about 1972 or so as explained above by Gary. This is about 50 H.P. less that in 1.

3. Rear wheel H.P. measured by a chassis dynamometer with the car on rollers; this is the "real" H.P. of the car but may be only about a hundred or so.

I was also fooled by the change in the way H.P. is/was reported in the early 1970s, but I think something else was going on. I bought the cheaper two-bolt 350 that came in the '76 Corvette and it was rated at only 190 H.P., presumably at the tailshaft, BUT (!) the heads are the 883 castings, definitely NOT the high flow heads. Thus you may be one of the lucky owners of the earlier 350s with better heads. Check the last three digits of the casting number in the middle of your heads between the rockers and compare to:

http://www.angelfire.com/tx5/randysr...Headguide.html

You probably have better flowing heads on the '71 than on my '76 350. I am going to trade in my two-bolt for a four-bolt block but keep the low compression heads and only use a torque cam from:

http://www.kendrick-auto.com/chevrol...y_cam_spec.htm

GM part # 12353915 developed by Crane with/for GM looks like what I want with duration (194) less than 200 degrees for economy and slightly more lift than the stock cam. With only three speeds on my TH350 I have to use a 2.79:1 8" Maverick rear to get some economy so I need torque in the low rpm range. I guess I just want a mild street rod and I do not intend to race at my age (66) so I am hoping for 18 mpg with maybe only 250 (tailshaft) H.P. in a light roadster body. By the way if you check the weight of Corvettes in the '70s they are not as light as you might expect and are usually over 3000 pounds, so I hope a 2200 pound roadster will move OK with only 250 H.P. and I can use 89 octane gas and get 18 mpg and still have fun. I really like the Essex 350/350 installation on this thread as something one can do without much help from a shop and still get a neat installation.

Best Wishes,
Don Shillady
Retired Scientist/teen rodder

Don,
Glad you like my car. I know I've had a lot of fun putting it together. My brother and I did all of the work in my garage at home. Of course it helped that he is a GM Mr. Goodwrench mechanic. Got some good deals on parts, especially take-offs from the dealership plus he's got, or has access to, all the right tools.
I picked up a copy of DD2000 off ebay last week and ran the simulation myself using all the correct info it asked for. It came up with 306 hp @ 5000 rpm and 355 lbs torque @ 4000 rpm at the flywheel. I plan on upgrading to an RPM cam and roller rockers in the near future. I haven't run that yet to see what it will do for it. But it should help some.
The biggest expense I've had on the car, other than the original purchase, was the IFS from Fatman Fabs. But it dropped right in and I haven't had a bit of trouble with it in the three years its been on.

Gary