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It's a turd, what to look for? #3086631
10/16/22 07:19 PM
10/16/22 07:19 PM
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parksr5 Offline OP
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So, got my engine in the car and took it to the track today for its first shake down runs. It's slow and I really don't know why.

The engine made 460HP on the engine dyno. The car is 3667 with me in it. Today, it ran a best of 12.99. Plugging that into Wallace Racing Calculators, that's 330hp to the crank, so; it's running like it's down 130hp.
.

With milder iterations of this engine, I've run as fast as 12.25 and have never run as slow as I did today, with lesser power.

The car isn't doing anything noticeably bad or wrong though. It's not missing, it's not laying over, it's not making noises, It's launching okay, not as good as it has in the past but, maybe off by .10 in the 60ft. The fuel pressure is right below 6lbs (Edelbrock Thunder 800), the air fuel ratio might be a touch lean for max power (low 13's). I checked the throttle, and the carb barrels are opening all the way when I have the pedal pushed all the way to the floor. I'm just kind of like, why did it slow down that much?

Again, if it was doing something noticeable, okay but, it's just not really doing anything bad, it's just slow.

My first thought, take it to the chassis dyno, like 20 minutes from me, see what it's putting down to the tires, monitor fuel pressure to see if it might be dropping at any point, and see if we can find any smoking guns. One would assume that it's an issue with something other than the engine itself, since it was made the power it did on the engine dyno.

What else should I be looking for? Just never had an issue like this.

Re: It's a turd, what to look for? [Re: parksr5] #3086634
10/16/22 07:28 PM
10/16/22 07:28 PM
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More details.
CCP is?
Idle spark?
Cam @ .050" and LSA?


Boffin Emeritus
Re: It's a turd, what to look for? [Re: parksr5] #3086636
10/16/22 07:30 PM
10/16/22 07:30 PM
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Plymouth, MI
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Is the engine exactly as it was run on the dyno? Air cleaner? Exhaust? Ignition timing is the same?

Brakes dragging?

Trans hurt?


'18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118
Re: It's a turd, what to look for? [Re: parksr5] #3086645
10/16/22 07:45 PM
10/16/22 07:45 PM
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What MPH are you running vs with the other engine? Different engine combo may require different gears and/or converter. Any major exhaust differences between the dyno and on the car? Restrictions? With the carb, accelerator pump squirter size & duration mostly influences 60' while jetting mostly affects MPH. Any carb differences between engines? New engine may be more sensitive and/or needs adjustments to vacuum secondaries if they are opening too slow or too quick. FWIW, in my experience, a properly tuned mechanical secondary carb will outperform a same-sized vacuum secondary carb by about a tenth. But a vacuum tends to be more "drivable" on the street.

Re: It's a turd, what to look for? [Re: Blusmbl] #3086651
10/16/22 07:55 PM
10/16/22 07:55 PM
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parksr5 Offline OP
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The car was run without an air cleaner on the dyno and run with the dyno headers. I'm running a set of HP exhaust manifolds on the car now and an unsilenced air cleaner housing.

I have switched from headers to the manifolds in the past and it lost a few tenths, so; probably killed off 20-25HP. That was with a cam that was more suited for headers, the cam I have now was spec'd for the manifolds, for what that's worth.

Ignition timing is the same as it was on the dyno.

I did fatten the carb up from what it was on the dyno because it had a lean bog when I put it in the car and floored it, we're not talking major changes, the jets are the same, just one step smaller metering rods and a little more aggressive metering rod spring to enrichen things more quickly.

Compression in all iterations of this engine has been 9.35:1. The cam is around 250@.050. FYI- both the air cleaner housing, manifolds and compression ratio have all been the same on the car in the past, when it had less power, and where it ran a best of 12.25 in similar conditions as today.

Re: It's a turd, what to look for? [Re: Locomotion] #3086652
10/16/22 08:04 PM
10/16/22 08:04 PM
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Originally Posted by Locomotion
What MPH are you running vs with the other engine? Different engine combo may require different gears and/or converter. Any major exhaust differences between the dyno and on the car? Restrictions? With the carb, accelerator pump squirter size & duration mostly influences 60' while jetting mostly affects MPH. Any carb differences between engines? New engine may be more sensitive and/or needs adjustments to vacuum secondaries if they are opening too slow or too quick. FWIW, in my experience, a properly tuned mechanical secondary carb will outperform a same-sized vacuum secondary carb by about a tenth. But a vacuum tends to be more "drivable" on the street.


Last time I ran the car with the old combination, I had valve float issues and couldn't rev the car past 5400-5500 rpm. In the past, before the valve float issue, the car ran best being shifted around 5900. On that day, with the same carb but, a different intake, the car ran 107.5 mph, today, it ran 104mph on the best run.

It is a mechanical secondary carb. The AFR is pretty good everywhere, per the wideband. Maybe it can be better but, not 130HP better, we're talking probably 5-10HP if I really got some seat time in it and tested and changed things and tested some more.

Re: It's a turd, what to look for? [Re: parksr5] #3086654
10/16/22 08:07 PM
10/16/22 08:07 PM
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parksr5 Offline OP
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On the 12.25 run, I believe the mph was 111.5. Again, that combination made less power than this combination though, so; again, where did the time and MPH go? Just stumped but, to be fair, I haven't had a bunch of time to investigate.

I appreciate everyone weighing in, keep it coming.

Last edited by parksr5; 10/16/22 08:34 PM.
Re: It's a turd, what to look for? [Re: parksr5] #3086660
10/16/22 08:24 PM
10/16/22 08:24 PM
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110MPH is 11.90 HP.

What speed with this combo?


If the results don't match the theory, change the theory.
Re: It's a turd, what to look for? [Re: CMcAllister] #3086664
10/16/22 08:33 PM
10/16/22 08:33 PM
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Best mph today was 104.

Re: It's a turd, what to look for? [Re: parksr5] #3086666
10/16/22 08:39 PM
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parksr5 Offline OP
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I double checked my old 12.25 time slip, the mph was 110.5, not 111.5.

Re: It's a turd, what to look for? [Re: parksr5] #3086668
10/16/22 08:51 PM
10/16/22 08:51 PM
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Who put the motor together?
What lobe separation is the cam and what is it the durations at .050 lifter opening and what ISA (intake lobe opening at .050 from TDC) is the cam installed at?
As far as the wide ban and the AFR Lamba numbers you may need to either fatten it up or lean it down to find out exactly what this new motor likes the most work scope up
BTW, did I mention Murphy loves messing with us hot rudders rant whiney whistling


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Re: It's a turd, what to look for? [Re: parksr5] #3086669
10/16/22 08:52 PM
10/16/22 08:52 PM
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Originally Posted by parksr5
I double checked my old 12.25 time slip, the mph was 110.5, not 111.5.




You mad some critical errors. Testing with dyno headers was a giant waste of time and money. You didn’t learn a damned thing doing that. Same with the air cleaner.

Run the engine on the dyno as close to the way it will run in the car. So basically your dyno numbers mean nothing.

Also, stop using ET to calculate your HP from the time slip. ET is hook. MPH is Horsepower.

You have no idea other than guesses what your engine actually makes for horsepower on a dyno. I’ve seen dyno headers beat chassis headers by 40 plus HP. That was header to header. There is now way you are only losing 30 HP going to manifolds unless the dyno headers are garbage.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: It's a turd, what to look for? [Re: parksr5] #3086686
10/16/22 09:39 PM
10/16/22 09:39 PM
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Quote
Compression in all iterations of this engine has been 9.35:1. The cam is around 250@.050


As Mad said above your dyno test was pretty much meaningless. Add to that what works on the dyno may not work on the track and there is a possibility of a happy dyno giving bogus numbers. Dyno is best used to compare changes instead of predicting on track performance.

Need more Info.

What engine? SB, BB, C.I.?
Compression test PSI?
Intake Manifold type?

Solid or Hydraulic cam?
Lift? Lobe Separation Angle (LSA)?, Intake lobe centerline (ICL)? Was it degreed?

Manual or Auto trans? If Auto, what converter? what valve body?
Gear Ratio? Tire diameter?

Manual advance curve - Advance at Idle and Total? rpm at total advance, If you have vacuum advance is it connected to ported or manifold vacuum?

My guess is that several of the above are mismatched. Prime Example: Most cams that big will hate exhaust manifolds and love more gear, more stall speed, more compression and more initial ignition timing than what smaller cams require.



In theory, there is no difference between theory and practice. In practice, there is.
Re: It's a turd, what to look for? [Re: madscientist] #3086687
10/16/22 09:46 PM
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Originally Posted by madscientist
Originally Posted by parksr5
I double checked my old 12.25 time slip, the mph was 110.5, not 111.5.




You mad some critical errors. Testing with dyno headers was a giant waste of time and money. You didn’t learn a damned thing doing that. Same with the air cleaner.

Run the engine on the dyno as close to the way it will run in the car. So basically your dyno numbers mean nothing.

Also, stop using ET to calculate your HP from the time slip. ET is hook. MPH is Horsepower.

You have no idea other than guesses what your engine actually makes for horsepower on a dyno. I’ve seen dyno headers beat chassis headers by 40 plus HP. That was header to header. There is now way you are only losing 30 HP going to manifolds unless the dyno headers are garbage.


All data is good data and an opportunity to learn. I do wish that I was able to run the engine on the dyno with the manifolds but, I didn't have that choice. I agree, we would have gained more valuable data if I could have run it on the engine dyno with the manifolds and the air cleaner on it.

I wasn't calculating anything with the post you quoted, just telling the group what mph it ran when it ran 12.25. The HP numbers I have quoted in my posts were numbers from either the engine dyno or a chassis dyno, taking into consideration the 18-22% loss through the drivetrain that seems to be the general rule of thumb, I understand that this can differ between combinations as well and is an educated guess. From there, I've tracked what I ran shortly after those numbers were made. I've utilized the different Wallace Racing Calculators to see if the numbers are in general alignment with what the car actually ran. In the past, they have been almost spot on, today, not so much; which leads me to believe that there's something wrong.

The loss in HP I had from a header to exhaust manifold swap was gauged by past results at the track. Again, with the new combination, it may be a little less or a little more. But, the short block, minus the cam, is the exact same in all combinations. The manifolds, carb, air cleaner housing, exhaust system, fuel system, etc., etc. is the same, from two of the combinations that I've run, and very close to the third. What I'm getting at is, it's highly unlikely to me that with so many similarities with the different things I've tried over the years, that the car was 8 tenths slower today, given similar weather and track conditions and the fact that I've never been this far off from the past combinations, with relatively similar parts. I feel that there is something wrong, like something failing, etc. and was asking for possible common things to look into. Maybe, in the end, I check all these things and determine that it's a miss with the combination and that nothing is wrong, and it is what it is. But I feel like something is wrong. Time will tell.

For example, I had a friend with a 69 Camaro.They switched from a healthy 383 small block to a 468 big block. The big block had several better parts, etc. and should have run much better than the 383. For two seasons, they tried various things. The car never really ran bad, it was just much slower than what the sum of all parts should have netted, and not much faster than the 383. They eventually switched to a whole new ignition system and bang, the car picked up 4-5 tenths. They suspect the MSD box was bad. Something stupid like this is what I feel might be going on with my car. I could be wrong but, with what I've learned over the years, I just think something stupid is going on. I don't know everything though, and would like the opinion of others, some with much more knowledge and experience than I, which is why I'm asking here. It could be a bunch of different things, or nothing at all and just a miss. Just trying to get some ideas.

Re: It's a turd, what to look for? [Re: parksr5] #3086692
10/16/22 10:01 PM
10/16/22 10:01 PM
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When I put my Valiant together it ran pretty good. By messing with just timing and jetting I picked up almost a full second. I couldn't believe it.


"Everybody funny, now you funny too."
Re: It's a turd, what to look for? [Re: slantzilla] #3086696
10/16/22 10:16 PM
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Originally Posted by slantzilla
When I put my Valiant together it ran pretty good. By messing with just timing and jetting I picked up almost a full second. I couldn't believe it.


I agree, I've seen it. A buddy of mine has been running the same combo for 7 or so years. Ran high 10's at the beginning, with little tweaks along the way, he ran 10.30's earlier this year. It's crazy. Heck, one of our buddies at the track today has cut almost 5 tenths off his newer challenger times since he first got it, with nothing more than some different drag radials and rims. Most of his gains have just been from seat time and trying different techniques at the launch, etc.

My new combo just may need more tweaking than what I've had to do in the past.

Again, I just don't see 130HP from an air cleaner housing and a header to exhaust manifold swap on a mid 400 hp engine, especially since I've made the header to exhaust manifold switch in the past and only lost around 2 tenths. Who knows though, you can only truly figure this stuff out with testing.

As I mentioned above, I may take it to the chassis dyno for peace of mind, curiosity, and to see if we can find any smoking guns. May have to check some things over the Winter and get back after it next year.

Re: It's a turd, what to look for? [Re: parksr5] #3086698
10/16/22 10:28 PM
10/16/22 10:28 PM
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If its a flat tap cam, it could be going flat


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Re: It's a turd, what to look for? [Re: csk] #3086728
10/17/22 06:18 AM
10/17/22 06:18 AM
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my thoughts; 250@.050" with cast manifolds is a lot, even if the LSA is spread out. that's even a lot of cam for the compression ratio. do the chassis dyno; they're the truth meter. numbers on an engine dyno vs engine installed in chassis numbers can be shocking.

Re: It's a turd, what to look for? [Re: lewtot184] #3086734
10/17/22 06:46 AM
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It looks like it's down about 60 hp compared to the old combo based on the mph. I'd be surprised if the cam choice did that if nothing else changed.

Speaking directly to the dyno numbers, the manifolds and air cleaner are certainly a percentage of that, along with other normal losses in a vehicle (alternator, power steering, water pump, fan, etc). It also depends if they used SAE or STD correction factors too. STD is optimistic.

If it's not running out of fuel on the big end it would be worth trying to jet it up and also adjust timing to see if it will respond to either of those, definitely check the plugs and compare that to what the wideband is reading.

Also worth checking to see if the cam is losing a lobe, like csk suggested. I was down a lobe in my '68 Charger when I pulled it apart and it ran fine, I had no idea until I got the old cam out that it was wiped.

Last edited by Blusmbl; 10/17/22 06:46 AM.

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Re: It's a turd, what to look for? [Re: parksr5] #3086758
10/17/22 08:56 AM
10/17/22 08:56 AM
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Originally Posted by parksr5
Originally Posted by madscientist
Originally Posted by parksr5
I double checked my old 12.25 time slip, the mph was 110.5, not 111.5.




You mad some critical errors. Testing with dyno headers was a giant waste of time and money. You didn’t learn a damned thing doing that. Same with the air cleaner.

Run the engine on the dyno as close to the way it will run in the car. So basically your dyno numbers mean nothing.

Also, stop using ET to calculate your HP from the time slip. ET is hook. MPH is Horsepower.

You have no idea other than guesses what your engine actually makes for horsepower on a dyno. I’ve seen dyno headers beat chassis headers by 40 plus HP. That was header to header. There is now way you are only losing 30 HP going to manifolds unless the dyno headers are garbage.


All data is good data and an opportunity to learn. I do wish that I was able to run the engine on the dyno with the manifolds but, I didn't have that choice. I agree, we would have gained more valuable data if I could have run it on the engine dyno with the manifolds and the air cleaner on it.

I wasn't calculating anything with the post you quoted, just telling the group what mph it ran when it ran 12.25. The HP numbers I have quoted in my posts were numbers from either the engine dyno or a chassis dyno, taking into consideration the 18-22% loss through the drivetrain that seems to be the general rule of thumb, I understand that this can differ between combinations as well and is an educated guess. From there, I've tracked what I ran shortly after those numbers were made. I've utilized the different Wallace Racing Calculators to see if the numbers are in general alignment with what the car actually ran. In the past, they have been almost spot on, today, not so much; which leads me to believe that there's something wrong.

The loss in HP I had from a header to exhaust manifold swap was gauged by past results at the track. Again, with the new combination, it may be a little less or a little more. But, the short block, minus the cam, is the exact same in all combinations. The manifolds, carb, air cleaner housing, exhaust system, fuel system, etc., etc. is the same, from two of the combinations that I've run, and very close to the third. What I'm getting at is, it's highly unlikely to me that with so many similarities with the different things I've tried over the years, that the car was 8 tenths slower today, given similar weather and track conditions and the fact that I've never been this far off from the past combinations, with relatively similar parts. I feel that there is something wrong, like something failing, etc. and was asking for possible common things to look into. Maybe, in the end, I check all these things and determine that it's a miss with the combination and that nothing is wrong, and it is what it is. But I feel like something is wrong. Time will tell.

For example, I had a friend with a 69 Camaro.They switched from a healthy 383 small block to a 468 big block. The big block had several better parts, etc. and should have run much better than the 383. For two seasons, they tried various things. The car never really ran bad, it was just much slower than what the sum of all parts should have netted, and not much faster than the 383. They eventually switched to a whole new ignition system and bang, the car picked up 4-5 tenths. They suspect the MSD box was bad. Something stupid like this is what I feel might be going on with my car. I could be wrong but, with what I've learned over the years, I just think something stupid is going on. I don't know everything though, and would like the opinion of others, some with much more knowledge and experience than I, which is why I'm asking here. It could be a bunch of different things, or nothing at all and just a miss. Just trying to get some ideas.



I’ll say this again and then I’m out. You can NOT test with things you do NOT run and the claim you have good data.

Garbage in, garbage out and that exactly what you did. You can defend what you did all day long but had you come to my dyno and wanted to test with dyno header and not with your manifolds I would have sent you away.

You wanted your time and money to learn absolutely nothing. And if your manifolds don’t lose big power to a piece of junk manifold it tells me your cam timing is dead wrong.

When you cam timing is wrong the engine will be dead to header and tuning changes. You should have been down 40-50 HP with those manifolds but you’ll never know because you didn’t TEST for it.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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