It's a turd, what to look for?

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.

More details.
CCP is?
Idle spark?
Cam @ .050" and LSA?

Is the engine exactly as it was run on the dyno? Air cleaner? Exhaust? Ignition timing is the same?

Brakes dragging?

Trans hurt?

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.

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.

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.

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.

110MPH is 11.90 HP.

What speed with this combo?

Best mph today was 104.

I double checked my old 12.25 time slip, the mph was 110.5, not 111.5.

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
BTW, did I mention Murphy loves messing with us hot rudders

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.

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.

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.

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.

If its a flat tap cam, it could be going flat

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.

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.

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.

was the first motor ever dyno'd? could that motor possibly have been an overachiever?

how much larger is the camshaft in the new motor vs. the old? it possible you need a converter and gear change?

I’d say step one should def be make sure timing is correct, you’re getting wot, etc....... the basics.

Pull all plugs and do a cranking compression test on all cyls.

If it all checks out good, head to the chassis dyno for a few pulls.

When it had that valve float at 5500, it had a different intake on it, correct?
What was the speed then?

I’ll just throw this out there as another possibility ........ the converter might be going away.

110MPH @ 3600# - 375HP at the wheels. 104 - 325. Down 50HP. Also 104MPH is 12.50 - 12.70HP A good 60' would be 1.77 - 1.80.

Lean at WOT would be where I would start. Verify the secondaries are in fact opening.

I appreciate everyone's feedback!

I definitely have a lot of things to look at.

To begin with, I was really looking to the KISS stuff first, although, the more in-depth stuff may be needed at some point if the stupid stuff is good.

I'll reverify some things and go from there.

To clarify, I wanted to dyno the engine with exactly what it was going to be run with, the dyno shop wanted to run the engine with the headers, it was not my call. I did not say that I had good data, what I said is that all data is good, the more you have, the better.

Dwayne, you bring up something I was thinking about. The main reason I wanted to go to the track before the end of the year is, I wanted a baseline before having a new convertor built. The converter in the car is 30 years old and has never been freshened. I've thought for years that there were some gains to be had with a better converter, that was set up for the car. What are the symptoms of a converter going away?

There are definitely more questions I need to answer from above. I'll keep adding more as I have time; on my lunch break right now and checking in quickly.

^^This, plus I would run a leakdown on the engine.

Well, one of them is the car slows down.

If everything else checks out fine, and since you were considering something different....... it might be worth trying something else.

I’d def have a proper cranking compression test near the top of the list.
Engine warm, all plugs out, wot, battery charger hooked up.
Test at 4 pumps, and max pressure(like 8 pumps).

I used to bracket race a 66 dart with a 3602bbl engine with nothing but a thermoquad and manifold swapped on it, I got it very consistent and it was an over achiever combo, low geared 904 and 2.94 gears, finnaly decided to get a bigger cam XE268 and matching springs and stuff and it slowed down a ton 60ft, MPH and ET all were way down even though it actually pulled way harder and way higher RPM, eventually I put in 3.92 gears and it became way faster and way less consistent. Just because you are running slower does not mean the engine is not making more power, it could just be that you are not using it all. With that big of a cam and low compression you are going to have a very soft bottom end and you probably will not catch your old combo till you make matching changes to the rest of the combo. And for the people who say MPH is HP.... that is only true if your car is close to set up right, try running your car launching in 3rd instead of 1st and see how much slower your MPH is at the end of the track. Also the engine wanting to turn higher RPM because of the bigger cam means the manifolds are going to be a much bigger restriction than they were on the lower RPM combo.

I'd move the timing and see what happens. I broke a converter 2 times 2 cars in the last year. Car $1 11.07, 12.26 3 passes later. Car #2 9.18 to 10.12 on the next next pass. Car number 1 with the wrong converter 11.70@122, swapped a week later 11.05@122.
Doug

Timing marks verified correct?

This.

Plus the questions asked in the second post: cranking cylinder pressure, actual cam 0.050" durations, LSA and ICL. Is it a solid or hydraulic?

Although there has been a lot of good comments as to what could be the problem, I'm guessing it's the cam and lack of cylinder pressure.

that cam with a 110lsa and hydraulic tappet would just up the misery index. if so the intake valve may be closing close to 80 degrees ABDC, pretty late. cylinder pressure may be in the toilet. know my 9.3:1 cast manifold engine would just roll over and die with any cam close to that. but, in fairness there could be some fuel delivery issues too. i know that a 5-6lb fuel pump won't do 5-6lbs at WOT; probably closer to 2lbs. of course a complete run down on before and after of the engine combo would go a long way to finding solutions.

I've seen zero pressure from the 1000 to the 1/4-mile finish line many times with street Hemi motors
They didn't miss or burnup spark plugs but they went quicker and faster with the better Carter NASCAR three valve mechanical race pumps
All things wrong with a drag race car can be fix

The engine dynoed at 460hp with headers.
If we say the headers were worth 35hp, that puts it at 425hp, corrected.

If there is another 15% lost in weather and installation in the car, it’s juat over 360hp as installed.

The moroso chart shows 108.5mph for 360hp and 3650lbs.

Something is way off.

I think so too, Dwayne.

I just haven't had time to start checking things out. Hopefully next weekend I can get to checking some things but, really, most will occur next year.

I got most of my cars packed up for the Winter today. I have two more to wash.

My Wife's car has been killing me lately. Fixed the exhaust and changed the oil recently. Was driving it yesterday and a pad was hanging up on the driver rear. Looked today and the hub is junk, and the brakes could use changed. So, next weekend on this.

A hub on my Winter beater needs changed too, along with an oil change.

I did call PTC earlier this week and ordered a new converter.

I'll get the Road Runner sorted out at some point. Really just ready to relax soon. Been a busy year.

What did you get for a converter?

How about a quick rundown of a couple of configurations you’ve had.......
Cam, gears, tires, intake, exhaust, carb, etc......along with the best ET & speed.

-the combo prior to the KG heads

-the first combo with the KG heads

What cam went 12.25? Exhaust manifolds or headers? And what mufflers?

What are the full cam specs now, and what mufflers are you running? What is the displacement?

250* at .050 with pretty much any ICL or LSA is probably too much for exhaust manifolds, let alone in a 9.3:1 engine. That does not sound like a cam spec’d for manifolds at all.

I think your exhaust manifolds and the turbo mufflers you’re probably running (especially if they are Hush Thrush) are killing a lot more power than you think. And the 250* cam put a big hole in the torque curve and you’re hitting your converter way less than the old combo did, which is exacerbating the issue.

The short block, minus the cam is the same it's been in all combos. A 400 based 470, 440 source rotating assembly. 9.35:1 compression.

The first combo included a comp hydraulic flat tappet (.488/.491 lift, 230/236 @.050, 110 LSA). I had a performer RPM intake, Hooker 1/78 long tubes with a 3" collector, compression bent exhaust with flow master 2 chamber mufflers, 4.10 gear, an old super street fighter converter, an MSD billet distributor, a set of big valve 213 heads and a Holley 850 street hp. I ran some 28x10.50 Sportsman Pros back then. The best I ran in this configuration was a 12.33.

I switched to a 3.73 gear and a custom curved vacuum advanced distributor and ran a best of 12.25.

I threw the exhaust manifolds on the car along with a mandrel bent tti exhaust system with Dynomax Super Turbos and went to the track once with this change and ran a 12.48. The track was marginal that day and I think I could have run a little better if I would have taken it to the track a few more times.

I then switched to some K&G ported 906's, a dp4b intake and some American Racer L60's, ran at the track one weekend and ran a best of 12.50. The weather was a little hotter that day then what it is when I normally run but, not super hot (low 80's). The big issue, which prompted the cam swap, is that I ran into valve float with the valve springs on the new heads. I'd heard for years how bad the XE series cams where with this but, never experienced it myself, until then.

I had a new solid flat tappet cam ground. Long story short, when swapping the cam, I found some bad cam bearings so, back to the machine shop it went. Upon further inspection, they discovered that the line bore was not done correctly on the mains, so; it this was corrected and the whole engine was freshened.

I ported a 301 intake and threw it on and switched to an Edelbrock 800 Thunder series carb with this iteration.

Dwayne spec'd the new cam for this combination, out of respect for him, I didn't post up the exact specs of the new cam. If he's okay with me posting them, I'll gladly share them.

was the "301" intake and Edelbrock 800 carb on the motor on the dyno??

looks like your TCI converter is supposed to be about 1500rpm higher than stock. is it flashing to 3500rpm??

IMO i wouldn't use that xe274 cam with stock manifolds, and definitely wouldn't use the 250@.50" with manifolds. that being said losing about .25 of a second with manifolds vs the headers does make some sense. with the "250" cam put the headers back on. you need the separation of the exhaust pulses plus the have more volume. i also i would take a very serious look at fuel delivery. dumb things can happen between the tank and carb; cracked hose, pump push rod, inadequate pump, etc. my experience with those 800 carbs has been they are more likely to be rich than lean as they come out of the box.

You can post them if you like, especially since everyone is so sure that it’s wrong.

Even though that same cam(and a bigger one) has already gone mid-11’s in a similar combo.

A cranking compression test would help shed some light on that situation.

Yes, both the intake and 800 carb were run on the engine on the dyno.

I feel that the converter was not flashing at 3500rpm but, not too much lower.

Correct, the xe274 cam is not really set up for stock manifolds but, I wasn't unhappy with the results when I tried it. About what I would have thought.

The headers will not be going back on as I'm interested in the FAST class, I've been making changes to move in that direction.

The fuel delivery issues are up on the list of things to check.

This is more a general question, do the F.A.S.T guys dyno their engines with their exhaust manifolds with part of the exhaust?

my quickie guess is the engine is in the process of eating the fuel pump push rod. that would account for the majority of power loss. just a first place to look guess.

I can tell you one thing...Dynomax Super Turbo mufflers are great for a nice mellow sound, but flow like garbage. Get a straight through style muffler.

yes with the ones i have seen.

So in a nutshell changes are

Ported factory intake instead of the RPM
Manifolds with Super Turbos instead of headers and Flowmasters
Custom cam instead of XE274
800 AVS instead of 850 HP Holley

Assuming you don’t have a fuel supply issue, if the cam is right and you’re determined to make it work with the manifolds i’d try the RPM again with the 850. Maybe your ported intake doesn’t work that well. If it picks up alot try the AVS to see if it likes it or not compared to the Holley.

I also think Super Turbos aren’t a great choice, but not sure if it matters with the manifolds or not. Thats where I’d go after the intake if you’re determined to make it work.

how much could the exhaust manifolds be ported ?
if that is a possibility, do the FAST guys do anything in addition to having that gritty stuff [i forget the name] pumped through them ?

My 108 mph, exhaust manifold Charger lost about 4 mph with one failed Super Turbo muffler.......twice.

One of my old street and strip drag cars would pickup .9 ET (12.23 with them on and 11.39 removed) and 9+ MPH (109.4 versus 117.8 with them off with no other changes ) by removing the 2.5 inch pipes with the old Turbo muffs with 2.5 inch O.D. tailpipes that exited in front of the rear tires on my 1969 Dart GTS 440 powered
My Duster had a set of the cheaper crimp together Magnaflow 14x7x 3.0 inlet and outlet oval muffs straight through with perforate pipe, it ran 7.01 ET in the 1/8 mile with them on and 6.98 with them off Those muffs were mounted behind the rear end between the 1/4 panels in rear sub frames. That really surprised me and impress me I can't find them anywhere to buy them now

thinking about all this i have to wonder if the ultimate goal is a FAST engine then all of this irrelevant. i can't think of anything here that would apply to a 500cube high compression purpose built engine. if fast is the ultimate goal then i'd leave all this behind and move on to the challenges of a more sophisticated goal. just my thoughts.

Two replies I’ve seen on here that bare looking at. First is the fuel pump push rod. I had this issue with mine. Only lost .125 but killed a ton of speed. Second is the turbo mufflers. Not a good choice for flow especially with a 500” engine. I switched from Pypes Street Pros to their Race Pros and picked up a bunch.

Bill

The F.A.S.T. guys that are serious I imagine would ?

I'm in the process of restarting my F.A.S.T. build and when it goes on the Dyno it will be with the manifolds I plan to run. I'll also bring my headpipes and a second shorter set if the ones I plan to run won't fit the space allowed.

There are things one can do, port matching is a must. The last set of stock manifolds I tweaked for a friends build needed at least an 1/8" of material ground out of the port entrances on at least 2 surfaces to get it to match the gasket.

I have a set of reworked A body 383 manifolds that have had as much grinding as can be down withOUT cutting them in half and a piece welded in place where there was an internal divot to clear the flange bolt install. The divot was removed , welded from the outside and the flange tapped for a stud instead of the bolt. After all the work was done they were Jet Hot coated inside and out, I don't know if they were extrude honed. The manifolds were done by the late Greg Gessler.

I am going to try to compare them to an untouched set when I dyno to see how much it picks up.

I did.

Bill

Crap. Another good one. Sad and sorry to hear

Same here. Greg Gessler did a pair of exhaust manifolds for my FAST 70 Nova small block car.

This is the first I had heard of his passing. RIP Greg.

-> Greg Gessler obit <-

that's very impressive!