roccodart440
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check out the cam I posted for him.
232/[email protected], 0.533/.557 lift, 114lsa
However that 155CC is a bit concerning to me.
340 dyno chart thoughts
- Thread starter fez440
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check out the cam I posted for him.
232/[email protected], 0.533/.557 lift, 114lsa
However that 155CC is a bit concerning to me.
I'll post the compression test numbers later when I get home.
roccodart440
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I should add. It concerns me in the way of going to a bigger cam. Not in the current function of the engine. The dyno sheet shows what the engine is currently doing you are aware of the idle character. My engine makes 160psi. It's a ball on the street and the strip. I would want to fall much further than that though so my new cam I'm going with also will involve a new set of heads with a smaller CC chamber.
joec
Well-Known Member
Come on guys ! What i see is a small torque dip (could be from headers)but torque peak is still around 46-4800. There is no way a 106 or 108 would make more vacuum,especially with more duration.The way vacuum was explained looks like he took it off ported not manifold.Yes it could have made more but at what price? If the op wanted to pay more for heads,manifold ,carb he would have done so and made more hp.Also dyno headers to car headers or any header short of big $$$ ones .5 in the quarter you must be smoking crack! I see a pretty nice street combo no regrets with a fairly flat torque curve.
yellow rose
Overnight Sensation
Oh bull crap. I had 11 inches of vacuum at idle on the SAME CAM. Just because you can't tune don't mean the rest of us can't. Those heads don't need a 110 LSA and I'll keep saying that until I'm dead because it's stupid.
yellow rose
Overnight Sensation
What I said was neither false OR misleading. What's sad is this guys engine is an underachiever. I looked at the numbers and it is what it is. I threw the MP cam out there because most know what it is. It will easily make 10 inches of vacuum, all day long. It's been doing it for YEARS.
This is why I ***** continually about not using a cam from the shelf. You get stuff like this. A custom cam would pick up a bunch of power, for the same cost. If you are that worried about idle, put the MP cam in at 102.
I don't know how long people will spend money and accept LESS power. How is that good? He got less for the same. That's not a knock on the engine builder. He built what he was asked to.
Guys need to STOP saying **** that ain't true. LSA is a FUNCTION of actual timing events, and you can tweak it a bit to get what you want. I'm running 255 @.050 on a 105 LSA, in at 105 and it idles at 900 and has 10 inches of vacuum. If you can't get that out of a 284 hydraulic, you need to do something else.
yellow rose
Overnight Sensation
Nope, no crack just facts. Those dyno headers are 25-30 HP better than what he'll use in the car. Tested it many times.
joec
Well-Known Member
Of coarse they are, he will be using mufflers with exh. A dyno is just a tool its not the end all be all.He might be really pleased , also not all dynos are equal this one could be stingy.
Compression check numbers. did I open ip a can of worms here lol.. maybe it's cuz im in canada hp is lower here..ha.ha..bad joke
he did build want I was looking for. I think I'll be happy with it. I would not run my headers on a dyno if I didn't have to. better to break it in on his and not wreck mine I think. plus the carb and intake are what I had to use. which worked out well. I didn't see a big enough gain with a bigger carb to justify buying another one. Cam seems ok as it idles nice and has good vacum. heads flow good as I didn't see anything claiming they were a bottle neck. but like I said it's great to hear what people have to think about it ☺
he did build want I was looking for. I think I'll be happy with it. I would not run my headers on a dyno if I didn't have to. better to break it in on his and not wreck mine I think. plus the carb and intake are what I had to use. which worked out well. I didn't see a big enough gain with a bigger carb to justify buying another one. Cam seems ok as it idles nice and has good vacum. heads flow good as I didn't see anything claiming they were a bottle neck. but like I said it's great to hear what people have to think about it ☺
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did I open ip a can of worms here lol.. maybe it's cuz im in canada hp is lower here..ha.ha..bad joke
View attachment 1714995817
HP is lower due to customs, the exchange rate, and you are further North
Lol yah
yellow rose
Overnight Sensation
And they don't speak English up there. I never know what the hell they are saying...all that hockey stick **** and that.
What u talkin abut eh?
LOL!
67autocross
A new iron curtain drawn across the 49th parallel
Are you looking for the missing horsepower or are you happy with the output? Something seems off to me , I had put a 340 on the Dyno with a 490 lift cam, stock X heads, headers, a torker 340 single plane and a 750 DP and it made around the same power as this engine.
My 1st question was just on what people thought about the combo and if there was anything odd about the graph or the specs on the engine. also based on what I have is there anything holding the engine back?by reading the comments it mostly seems to me that a different cam carb intake would boost the power. if anyone else had any thoughts I'd be interested in knowing but for the most part I have my answer
for fuel mileage your lobe centers are to close , think 112 or 114 . less overlap , and remember its built to drive .
moper
Well-Known Member
Hard to say if things are "right" or usable to me. These are just my opinions...
It's not the rpm that caused the power dip. That torque dip shouldn't be present regardless of the headers used, small carb, or cam size. The engine never gets past 90% efficiency. It's pulling 1" of vacuum at peak torque. But the pressures look good and what I'd expect given the combo.
Overall, if it was mine, I'd be less than happy given the obvious expense and care taken on this engine. Vacuum will be low with those heads and that cam choice. vacuum won't be high enough to effectively work power brakes on a car that's street driven. Especially in stop and go traffic. In the end it's a lot of money to drop on a 340 that makes about 75hp more than a bone stock, machined and assembled in '70 340 did. And that 75 hp includes the dyno headers and no fuel pump parasitic loss. So in the chassis, with the alternator, fuel pump, smaller headers, and full exhaust, you're probably looking at a realistic 35-40hp over that stock 340, with a serious lack of vacuum. It's lazy.
Big negative influences could be the timing curve and the fuel the dyno guy runs.
It's not the rpm that caused the power dip. That torque dip shouldn't be present regardless of the headers used, small carb, or cam size. The engine never gets past 90% efficiency. It's pulling 1" of vacuum at peak torque. But the pressures look good and what I'd expect given the combo.
Overall, if it was mine, I'd be less than happy given the obvious expense and care taken on this engine. Vacuum will be low with those heads and that cam choice. vacuum won't be high enough to effectively work power brakes on a car that's street driven. Especially in stop and go traffic. In the end it's a lot of money to drop on a 340 that makes about 75hp more than a bone stock, machined and assembled in '70 340 did. And that 75 hp includes the dyno headers and no fuel pump parasitic loss. So in the chassis, with the alternator, fuel pump, smaller headers, and full exhaust, you're probably looking at a realistic 35-40hp over that stock 340, with a serious lack of vacuum. It's lazy.
Big negative influences could be the timing curve and the fuel the dyno guy runs.
Lustle
Well-Known Member
fez440. I'll ask a question no one else seems to have.
What is your altitude. BC altitude can be ALL over the place.
A lot of people forget about altitude and it's affect on power. 10:1 compression sounds like a lot. Right up until you are at several thousand feet. I'm at 3,000 myself. And planning head work and a new cam. To get 8.5 DCR (dynamic compression ratio) on the cams I'm looking at, I'm around 11-11.5 compression. On iron heads. I'm running 94 octane. So I could go even higher. But I don't want to run on the ragged edge.
If you are happy with it. That is great. But if you want more. It's there. With aluminum heads even at sea level you should be safe with more compression. With the port work on those heads, you are leaving a lot on the table with your cam/carb combination. There are MUCH better cam's out there, carbs as well. There's no reason you couldn't pull 450+ horse out of that setup with minimal effort.
Just a quick look - your DCR is 7.85 at 0 feet. It only gets worse the higher up you go. On aluminum heads you could run up to 9.5 on 91 and still be safe. Cam has low lift for it's duration. And the intake valve closing angle isn't great. You could go with something like hughes: SEH2832AL-10. 228/230 duration at .050. 108 LSA. .530/.536 lift with 1.5 rockers. Very similar duration. Little lower LSA. Would have good vacuum. Even with that cam and it's better intake valve closing angle, you're still at 8.5 DCR. You could still bump the static compression up to 11:1 to make a DCR of 9.3 to 1. And remember, that's all calculated at 0 feet. The higher up you go, the more compression you'll need to make up for it.
What is your altitude. BC altitude can be ALL over the place.
A lot of people forget about altitude and it's affect on power. 10:1 compression sounds like a lot. Right up until you are at several thousand feet. I'm at 3,000 myself. And planning head work and a new cam. To get 8.5 DCR (dynamic compression ratio) on the cams I'm looking at, I'm around 11-11.5 compression. On iron heads. I'm running 94 octane. So I could go even higher. But I don't want to run on the ragged edge.
If you are happy with it. That is great. But if you want more. It's there. With aluminum heads even at sea level you should be safe with more compression. With the port work on those heads, you are leaving a lot on the table with your cam/carb combination. There are MUCH better cam's out there, carbs as well. There's no reason you couldn't pull 450+ horse out of that setup with minimal effort.
Just a quick look - your DCR is 7.85 at 0 feet. It only gets worse the higher up you go. On aluminum heads you could run up to 9.5 on 91 and still be safe. Cam has low lift for it's duration. And the intake valve closing angle isn't great. You could go with something like hughes: SEH2832AL-10. 228/230 duration at .050. 108 LSA. .530/.536 lift with 1.5 rockers. Very similar duration. Little lower LSA. Would have good vacuum. Even with that cam and it's better intake valve closing angle, you're still at 8.5 DCR. You could still bump the static compression up to 11:1 to make a DCR of 9.3 to 1. And remember, that's all calculated at 0 feet. The higher up you go, the more compression you'll need to make up for it.
Lustle
Well-Known Member
At 1900 feet. Your DCR is 7.45. Lower than my iron head 340 as it is right now. You could probably run that thing on regular.
Like I said there's a lot in there if you wanna go after it. Cam change. More compression. Better carb. If that's what you're after.
Yes..Elevation effects the performance of an engine....BUT...LOOK at the Dyno print out...See the CHp....that is corrected HP....the computer took the actual HP and apply a standardize formula to correct it to SEA LEVEL.......It would be nice If the Print out showed Actual along with the Corrected.....
What's the initial timing? That has the biggest effect on idle vacuum. If it's not in the 20* range, it's not close to correct for a 340 with that camshaft. Cam is a bunch bigger than a stock 340 cam and should make better power EVERYWHERE in that pull range to the stocker camshaft. No way should the TQ peak be below 3500 with that camshaft!
Total timing approach is a HORRIBLE method to time an engine going in a street car. Race cars too unless they are locked out!
Bad idle set ups lead to stacking issues elsewhere in the fuel curve. That thing goes fatter and loses power which is probably a fuel system issue.
Total timing approach is a HORRIBLE method to time an engine going in a street car. Race cars too unless they are locked out!
Bad idle set ups lead to stacking issues elsewhere in the fuel curve. That thing goes fatter and loses power which is probably a fuel system issue.
Lustle
Well-Known Member
I see that and I'm aware of corrected power. But my point isn't the corrected power. It's elevation and how you need to compensate for it. It's also that he built an engine with ported aluminum heads with a cam that doesn't take advantage of them. Uses a cam with a bad lift to duration and bad intake valve closing angle. And how all that gave it a low DCR and frankly, mediocre power. It's really just a recipe for an "Ok" engine.
Honestly if I had an engine with aluminum heads that flowed 260cfm, I would be pissed if it made under 400 horse. I just hate the idea of leaving 100 horse on the table because of mismatched engine.
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