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importance of and improving power curve

General engine tech -- Drag Racing to Circle Track

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gmrocket
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Re: importance of and improving power curve

Post by gmrocket » Fri Nov 08, 2019 1:14 pm

CGT wrote:
Fri Nov 08, 2019 11:00 am
randy331 wrote:
Sat Nov 02, 2019 12:45 pm
A pull where more power anywhere from 2500-8500+ rpm would have helped.
Well since ST seems to be experiencing low traffic flow or low interest flow....I'll ask.. what changes need to be made to improve power over a 6000rpm wide range? :lol: :lol: Nitrous? :D
That's even wider than an EMC engine,,I read on ST before nobody ever runs an Engine over that range,, it's stoopid 😉

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Re: importance of and improving power curve

Post by CGT » Fri Nov 08, 2019 1:51 pm

gmrocket wrote:
Fri Nov 08, 2019 1:14 pm
I read on ST before nobody ever runs an Engine over that range,, it's stoopid
Does the person that said that suck at it? :lol:
There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded.
Mark Twain

Golf is a good walk spoiled.
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Re: importance of and improving power curve

Post by gmrocket » Fri Nov 08, 2019 5:14 pm

CGT wrote:
Fri Nov 08, 2019 1:51 pm
gmrocket wrote:
Fri Nov 08, 2019 1:14 pm
I read on ST before nobody ever runs an Engine over that range,, it's stoopid
Does the person that said that suck at it? :lol:
Ohh ya...

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Re: importance of and improving power curve

Post by cjperformance » Fri Nov 08, 2019 6:50 pm

CGT wrote:
Fri Nov 08, 2019 11:00 am
randy331 wrote:
Sat Nov 02, 2019 12:45 pm
A pull where more power anywhere from 2500-8500+ rpm would have helped.
Well since ST seems to be experiencing low traffic flow or low interest flow....I'll ask.. what changes need to be made to improve power over a 6000rpm wide range? :lol: :lol: Nitrous? :D
Ha yes n2o !! I like it.
Efficiency of "everything". I know pretty much nothing about pulling trucks, my best take on this sport is that it is all about being able to keep the rpm above peak Hp rpm, once you are loaded and dip below peak Hp rpm you are inevitably doomed and rpm will be pulled down to a point where the engine basically just stops. I say efficiency because brute HP is not the hardest thing to produce but high rpm Hp and low rpm Hp/Tq efficiency dont typically go hand in hand. I would think that carb calibration and sizing play a huge role here, once rpm/airflow becomes lower and the carb cant meter as well then you're fighting a losing battle. Intake system size and flow V CSA another huge factor and so on. I couldnt pick one single magic factor, i dont think that would exist. Everything just has to be perfect. Even if peak Hp remained the same, i would bet that just holding 1 or 2 hp more everywhere past peak and below peak would be a bonus in this sport(and most).
Craig.

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Re: importance of and improving power curve

Post by randy331 » Sat Nov 09, 2019 12:04 am

cjperformance wrote:
Fri Nov 08, 2019 6:50 pm
I say efficiency because brute HP is not the hardest thing to produce but high rpm Hp and low rpm Hp/Tq efficiency dont typically go hand in hand.
This is true, and part of the decisions we must make.
Not much your gonna do that will add power all the way from 2500- 9500.

Randy

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Re: importance of and improving power curve

Post by econo racer » Sat Nov 09, 2019 9:53 am

It sounds like a comp eliminator 283 :shock: =D> I would not change a thing. I thought he was gonna drag that sled out the gate =D> Motor sounds like music :D

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Re: importance of and improving power curve

Post by randy331 » Mon Nov 11, 2019 11:47 pm

cjperformance wrote:
Fri Nov 08, 2019 6:50 pm
Everything just has to be perfect.
If I just knew what perfect is. ??

Got a little time to fit up a set of higher rocker ratios on the 421, and test spring pressure at this point in it's abusive life. Springs are fine and I have room to run the higher rocker ratios in the current cam position,... I can't retard the cam any, but I could advance it a couple deg.

If the valve train seems happy in it's current state we should speed things up some to see what happens ?? LOL

So,.. what do you think ? Going from 1.7/1.6 to a 1.8/1.7 be worth any power ?

Another question to those running q16?? Do you change the oil more than if you ran vp blue or Sunoco supreme ?

Randy

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Re: importance of and improving power curve

Post by steve cowan » Tue Nov 12, 2019 2:12 am

Randy,
are you going back on the dyno??
did you end up doing new headers.
i am confident you already know what rocker ratio change will net,i am curious
does extra lift and duration move the spread of the peak numbers?will it fatten the numbers across the whole rpm range,or is it a million dollar question with no concrete answer.
i am talking about the 421 of yours that is already running at high end of the deal. :D
steve c

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Re: importance of and improving power curve

Post by cjperformance » Tue Nov 12, 2019 2:32 am

randy331 wrote:
Mon Nov 11, 2019 11:47 pm
cjperformance wrote:
Fri Nov 08, 2019 6:50 pm
Everything just has to be perfect.
If I just knew what perfect is. ??

Got a little time to fit up a set of higher rocker ratios on the 421, and test spring pressure at this point in it's abusive life. Springs are fine and I have room to run the higher rocker ratios in the current cam position,... I can't retard the cam any, but I could advance it a couple deg.

If the valve train seems happy in it's current state we should speed things up some to see what happens ?? LOL

So,.. what do you think ? Going from 1.7/1.6 to a 1.8/1.7 be worth any power ?

Another question to those running q16?? Do you change the oil more than if you ran vp blue or Sunoco supreme ?

Randy
:lol: a beautifully open ended question Randy ! The rocker ratio change should make more power if the rest of the combo ,induction package in particular needs and supports the extra lift, area and overlap window BUT what will the below peak consequence be! Maybe the extra HP at peak+ will get you where you need to be, maybe some cam advance will allow it to improve peak, not loose below peak and still allow it to hold on after peak.
Theres only one way to find out !!
Craig.

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Re: importance of and improving power curve

Post by randy331 » Tue Nov 12, 2019 5:39 pm

Yes, the 421 is going back to the dyno.
Just to try and learn something I guess, cause my son says he's not gonna pull next year, so guess I'll have another spare engine sittin in the shop, unless someone wants to buy it?? ?? :D

I have a much bigger carb to try, a 2" taper spacer machined for the bigger carb and higher rocker ratio Jesel set up.
I have already trial fitted the higher rocker set on the 421 and set lash on them and numbered them to which cylinders they go on, that way I can just tq them on and not have to set lash there. I've done it that way before and it works really well to speed up the changes on the dyno.
And I'll try moving the cam forward 2-3 deg.

I'll bring some headers off the truck to try if I have time, but header testing is a pain. LOL


Randy

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Re: importance of and improving power curve

Post by randy331 » Thu Nov 28, 2019 12:05 pm

Scan_20191128.jpg
This is our 421 cube pulling truck engine.

Top line is with the higher ratio rockers. 1.8/1.7 vs 1.7/1.6 it had.
Bottom line is the headers out of the pulling truck vs the dyno headers in the other 2 pulls.
The truck headers are fender well 1 3/4 tube x 3.5 collector, dyno headers are 1 3/4 x 1 7/8 step x 3 1/2 inch collector.
I'm happy with the flat power curve and it's hanging on to power past peak nicely, but I'm sure it can be better.
The bigger carb didn't gain anything. I was bettin that would.

So, we need to build our own headers that are closer to the dyno headers.

Does it just need more cam ?
I'm thinking maybe open the intake valve earlier ? Maybe open the ex earlier ?
A little faster lobe too ?
Just more cam ?

This is on a Stuska.


Randy
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Re: importance of and improving power curve

Post by CGT » Thu Nov 28, 2019 12:24 pm

Did you try any more or less timing last time you were on? Im just wondering if there couldnt be a little something there running way past peak like that...I hate I missed that dyno session. How long are the headers you tried?
There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded.
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Re: importance of and improving power curve

Post by CGT » Thu Nov 28, 2019 12:26 pm

gmrocket wrote:
Fri Nov 08, 2019 1:14 pm
That's even wider than an EMC engine,,I read on ST before nobody ever runs an Engine over that range,, it's stoopid
There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded.
Mark Twain

Golf is a good walk spoiled.
Mark Twain

gmrocket
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Re: importance of and improving power curve

Post by gmrocket » Thu Nov 28, 2019 8:13 pm

randy331 wrote:
Thu Nov 28, 2019 12:05 pm
Scan_20191128.jpg
This is our 421 cube pulling truck engine.

Top line is with the higher ratio rockers. 1.8/1.7 vs 1.7/1.6 it had.
Bottom line is the headers out of the pulling truck vs the dyno headers in the other 2 pulls.
The truck headers are fender well 1 3/4 tube x 3.5 collector, dyno headers are 1 3/4 x 1 7/8 step x 3 1/2 inch collector.
I'm happy with the flat power curve and it's hanging on to power past peak nicely, but I'm sure it can be better.
The bigger carb didn't gain anything. I was bettin that would.

So, we need to build our own headers that are closer to the dyno headers.

Does it just need more cam ?
I'm thinking maybe open the intake valve earlier ? Maybe open the ex earlier ?
A little faster lobe too ?
Just more cam ?

This is on a Stuska.


Randy
That thing never gives up..

Are both headers conventional collectors, no merge/pinch?

Since it likes the bigger two step and your gonna build a set anyway, it wouldn't hurt to try a 2" section after the 1 7/8 with some different lengths and a merge/pinch

Did it every dive up top?

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Re: importance of and improving power curve

Post by CGT » Fri Nov 29, 2019 8:51 am

That dyno graph is one of the few examples in life of how flat can be a good thing....its great for an engine but not so great for beer or women :lol:
There are basically two types of people. People who accomplish things, and people who claim to have accomplished things. The first group is less crowded.
Mark Twain

Golf is a good walk spoiled.
Mark Twain

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