Just a public service announcement for those who don't know about the Schoenfeld dyno headers. Sometimes engine shops don't have Mopar dyno headers so if you buy a set from Schoenfeld and take them to the shop they might give you a credit on the testing. That way you get your testing done and the shop ends up with some headers they can use on future projects.

https://www.schoenfeldheaders.com/sprintdyno1.html

I have a set. They are okay quality. Plenty good for the dyno. I should have coated them because the C series fuels seem to corrode the primaries.

IMO, their 4-into-1 collector design is horrible. It would make more sense to have a replaceable collector so a better one could be used, and also have the option to change between 3.0" and 3.5".

I use an old set of Hooker 2" x 32" x 3.5" Super Comps and hang long collector extensions off 'em. I figure the dyno results are more applicable to what engines like mine will see in a street car with a header that can be used in a full-body car.

If you loose 20 HP between "ideal" dyno headers and headers the car actually uses, that's 20 HP you're never going to see in the real world anyway. Might as well make the dyno data reflect the intended application as much as possible...

True, but only if your street headers fit the dyno. Some dyno layouts require a dyno type header since a street header will run into the frame rails.

I think if i went to a dyno and couldn't run my headers, my ignition system and use my timing light. I would find another dyno.

EVERY time i have changed headers, it has changed the engine output along with the tune up.


Joe

I agree 100%. If you don't test with the parts you run you are wasting your time, every time.

I disagree on that , I always finish the tune up in the car, never on the dyno Fuel and oil being slung around in the carb. and motor that has affects not repeatable on the engine dyno
As well as the location, altitude, weather and air differences between the dyno room and race track

There was no way my stepped TTIs were fitting on the dyno. I'd rather dyno with dyno headers than be finding things out the hard way once the car is screwed back together. I agree with getting it as close as you can but saying it's worthless to dyno unless everything is installed 100% as run in the car is foolish. Finding leaks and ensuring valvetrain stability are high on my list.

You can find leaks etc. with just a simple run in stand. I can't tell you how many times I've seen with the chassis dyno guys who had big engine numbers of a crank dyno but the car was running numbers 75-80 HP off. Put it on the chassis dyno and it's where it should be.

Start asking the customer how the engine dyno was done and then you find out they had dyno headers. The ones that are really down on power used a dyno ignition and a dyno carb. Then it becomes a pissing match on how worthless a dyno is in general, when in fact it's not the dyno's fault, it's the [censored] testing methods.


I've seen bad headers kill a hundred HP like nothing. The difference between good headers is maybe 10 if you are lucky.

Most dyno headers have nice, long port exits with generous radii for turns whereas most chassis headers have very short (if any) straight pipe off the head and bends and kinks that are big flow killers.

I've always said if you are using production made headers the tubes need to be bigger than if you can build custom headers (like Elston and others do) because you can make the tubes with bigger radii (and fewer corners if you are a skilled craftsman like Calvin) and do things a production header can't.

Ive seen an MSD box be down over another brand by as much as 12 average and 15 HP peak from a Mallory box and I've seen that on several tests I've done. And the MSD box had been worked over by someone else. It made that engine builder have great numbers but his engines were never as good in the cars as they were on his dyno. He loved his dyno ignition, carb and headers.

I will say if you are having issues and you can use a known, tested carb or headers or ignition to find an issue that's one thing. To use that stuff to fluff your numbers is entirely another.

I think if nothing else, the dyno header tube diameters should try to be close to the same as whatever is going to be used with the engine. If the carb and ignition system that the dyno operator has is making more power than what is in the car, doesn't it make more sense to evaluate what is wrong with the running combination? Maybe there has been a problem all along that caused the owner to believe his engine was tired and needed freshening or upgrades, when all it needed was some better support parts.

Exactly. Testing is testing and more data is better than less. Get the engine running and see what she does. Swap carbs, intakes, ignition systems until you run out of time or money. That is the whole point of the process.

I was able to use my 2-1/4" X 3" B/E body Hemi headers from my car on the dyno. Yes, I know they are probably choking it out a little but didn't have $350.00 for some big tube/collector headers to be made yet. Still made great numbers for a little ole pump gas street car.

What was wrong with them to kill 100 HP?

The dyno headers were about as good as you can get, as in all the bends were long and sweeping, long, straight tubes coming off the heads. The headers that actually FIT the car were nowhere near that good. They not only had more bends but the radius on the bends were significantly tighter, and the pipe coming off the head almost went down right off the port.

As a result, the uses were actually longer on the headers for the car and that was another reason the engine didn't do as well with the headers for the car over the dyno headers.

I'm all for testing. But using parts that will never e a part of your program is a waste of money for most guys. Hence, I detest dyno parts like worked over ignitions, carbs modified by the best in the business when you know the customer will never spend any money on anything but an off the shelf carb and those perfect dyno headers.

They sure do make the dyno guy a hero. Until the cool [censored] they used on the dyno doesn't match the junk [censored] used in the car. And in the end, the dyno gets knocked for being junk, when in reality the operator and the customer made the dyno lie.

Again, test all you want, but use the parts you are going to use.

BTW, I've never even used a set of TTI headers on anything. But I've used tons of Hookers (5204 and 5303 are two SB A body numbers I remember), Hedman and other lesser known brands and all of them fit every dyno I've used. That's across all brands of cars as well.

If I can't test TTI headers against a known set I know will fit a car I won't tell anyone to use them. How do you know they are any good if you can't test them?p

I have had a set of BBM TTI's on my dyno, required me to trim a mounting plate on the drivers side. Then again, your headers may be different.

Joe

I agree Andy. The only thing I don’t have dyno headers for is SBF. They are all Schoenfeld. I run everything on my run stand before it goes to the dyno. There are headers such as BBM, BBF and even Hooker BBC headers that don’t even fit my stand. I’ve cut headers, collectors and plates on my stand even. There are many dynos where headers are just not going to fit. It’s just reality. Most guys with a $75,000 dyno, aren’t real thrilled when you talk about hacking up the dyno parts, nor does the guy eith$1300 headers. I do believe in ACTUAL carb and ignition. MSD boxes for example can often very by 2-6 degrees. They are not necessarily doctored up boxes, rather that inconsistent, perhaps also affected by voltage and poor wiring. Get it tuned to a reasonable realistic safe tune, and dial it in, once in the car. There are way too many other variables that affect the engines tune once it’s in a different ( the car itself s) environment.

I’ve never seen anyone lose 100HP with headers, but with that being said, headers are and can be critical and significant,that’s fore sureYou ought to see what happens with headers and merge collectors in DIRT sportsman and limited stuff. Everyone fighting for the next 5HP/TRQ on the limited stuff. Like all of this stuff, your results may very. It’s what the smarts guys DO with the data that makes the difference. Every number tells a story.

With the original style stand that’s used on the SF-901, there’s lots of headers that don’t fit around the uprights of the dyno cart.
And it seems most of those are angled inward as well, so they’re difficult to get attached to the dyno room exhaust system.

I’ve had numerous sets headers for various applications that just didn’t fit the dyno.

Certainly, some dyno cart configurations are more versatile with regards to header clearance than others.

Sometimes you just have to use what fits.

Is it too much to ask to have the people who design the dynomometers allow for common exhaust systems? Would it really be that hard?

The 901 was designed in 1982, Dyno's designed in this century are much better for header fitment.


Joe

Another item I thought of is the 8 EGT bungs my dyno headers have where my chassis headers only have them on 1 and 8.

I have adopted the habit of overbuilding my engines hp wise so various real world parasitic losses (or otherwise) are not the end of the world. And then we also have nitrous lol. I'll definitely make some hits on the chassis dyno to double check the driveline at speed. The chassis dyno available to me chews the hell out of slicks which is something to consider. In my world the engine dyno is money well spent just like a wheel dyno.

Also there is no way you can test power adders, verify valvetrain stability or accurately get a baseline fuel curve with a test stand..it's not happening. Also agree on using the carb and box for the car. No worn out pro power dyno mule coil for this guy.