Dyno HP vs driving feel

[Steve.k]

That old film is wild! Hard to believe they could do that back then....

It is said the 427 would do two 24hr lemans back to back in dyno sim without failure.

[Casper393W]

If that isn't impressive I don't know what is...

[novadude]

Well it sounded and felt great on the street since we didn't get to a track that often to tell whether it was fast or not.
Remember we were cruising the streets and burger joints 7 nights a week back then!!

You just described my mis-spent youth! Lol

I miss those days. A 13-second street car was a serious contender. Now that's family sedan territory!

[andyf]

Big numbers on the dyno doesn't mean it is fun to drive on the street. I'm working on that exact issue right now with a 512 inch big block that made nice numbers on the dyno but is a real chore to drive. The problem in the car is that the engine doesn't have any throttle response below 1500 rpm. So driving it at low speeds in a parking lot is a pain. Once the engine is over 2000 rpm it is off to the races but from idle to 2000 rpm it is bog city. You typically can't find issues like that on a dyno since you can't really do low speed part throttle testing on a dyno. And the WOT dyno numbers won't tell you how the engine is going to act at part throttle off idle. Some people might not think it matters but if you sell a guy a $20K engine and his wife hates the car since it lugs and bucks every time he tries to drive thru the burger joint then you have an issue. Sometimes you have go with a smaller cam and a smaller carb than what the dyno says in order to have a setup that can be driven.

[Truckedup]

Big numbers on the dyno doesn't mean it is fun to drive on the street. I'm working on that exact issue right now with a 512 inch big block that made nice numbers on the dyno but is a real chore to drive. The problem in the car is that the engine doesn't have any throttle response below 1500 rpm. So driving it at low speeds in a parking lot is a pain. Once the engine is over 2000 rpm it is off to the races but from idle to 2000 rpm it is bog city. You typically can't find issues like that on a dyno since you can't really do low speed part throttle testing on a dyno. And the WOT dyno numbers won't tell you how the engine is going to act at part throttle off idle. Some people might not think it matters but if you sell a guy a $20K engine and his wife hates the car since it lugs and bucks every time he tries to drive thru the burger joint then you have an issue. Sometimes you have go with a smaller cam and a smaller carb than what the dyno says in order to have a setup that can be driven.

So you need 500 cubic inches to go to McDonalds? lurches? push in the clutch pedal...Probably an not a stick..

[Warp Speed]

No ... they test a car on the track and can change the load on the dyno to mimic it ... it let's them test the engine as it will work in the car ... computer even controls the throttle so they can see how it works as they get on and off the throttle in a turn ... if the driver blurbs the throttle in the test due to traction it does the same on the dyno

Do you have a link to this?

[tjs44]

TRD has a couple load Dino's.I saw a demo last summer.They were running the Sanoma sim when I was there.Tom

[tjs44]

Going back to the OP,I built a very rare 366 NASCAR tunnel port engine for my 69 firebird.We broke it in on Big Joes dyno.When it went into the car it had a single plane intake with a 780 factory RA V Holley.Stick shift car.The engine really sucked on the street.Small CI,huge lazy ports and the single plane intake.AFRs were in the 17-1 range,did not like under 1800-2000 in final gear.I put a factory dual plane intake,never touched the carb,AFRs went to 14-1 and the engine was happy at 1400-1500 in final gear.FWIW,Tom

[Steve.k]

Did u dyno both intakes? Im betting the dual plenum would've should a thicker lower end on dyno curve. Anyone who runs cleveland fords on street are used to a little soggier bottom end. The trade off is the hard hit above 2500. Usually you end up with more gains up top to offset the losses below. Quite abit like the flat plane engine in video above.

[tjs44]

I did not have the dual plane when we dynoed the engine.Joe did put a 2-4 tunnel ram on it with a pair of 625 AFBs.The engine really like it.Also Joe starts the pull way over street cruise-drive RPMs.Tom

[Scotthatch]

No ... they test a car on the track and can change the load on the dyno to mimic it ... it let's them test the engine as it will work in the car ... computer even controls the throttle so they can see how it works as they get on and off the throttle in a turn ... if the driver blurbs the throttle in the test due to traction it does the same on the dyno

Do you have a link to this?

Sorry they don't like anything they do to leave the building and I can't blame them it's how they make money

[Scotthatch]

Big numbers on the dyno doesn't mean it is fun to drive on the street. I'm working on that exact issue right now with a 512 inch big block that made nice numbers on the dyno but is a real chore to drive. The problem in the car is that the engine doesn't have any throttle response below 1500 rpm. So driving it at low speeds in a parking lot is a pain. Once the engine is over 2000 rpm it is off to the races but from idle to 2000 rpm it is bog city. You typically can't find issues like that on a dyno since you can't really do low speed part throttle testing on a dyno. And the WOT dyno numbers won't tell you how the engine is going to act at part throttle off idle. Some people might not think it matters but if you sell a guy a $20K engine and his wife hates the car since it lugs and bucks every time he tries to drive thru the burger joint then you have an issue. Sometimes you have go with a smaller cam and a smaller carb than what the dyno says in order to have a setup that can be driven.

I have done this very thing

Big block big sheetmetal tunnel ram with 2 650 dp carbs ran flawless at wot but what a bear to drive .... we tuned and tuned and people would come over and say how bad can it be ? I would toss them keys and let them see ..almost all would come back shaking there head .... after a while we realized the carbs will just not meter right with a low pressure drop you get at low rpm and part throttle ... most early Holley carbs need that 20.4 inch of water pressure drop to meter fuel some of today's carbs will work down to 3 inch of water but those cost money ...so I switched to 2 500 cfm edelbrock carbs and yes I gave up peak HP but it was a joy to drive so did not care at all

[Warp Speed]

No ... they test a car on the track and can change the load on the dyno to mimic it ... it let's them test the engine as it will work in the car ... computer even controls the throttle so they can see how it works as they get on and off the throttle in a turn ... if the driver blurbs the throttle in the test due to traction it does the same on the dyno

Do you have a link to this?

Sorry they don't like anything they do to leave the building and I can't blame them it's how they make money

It has been years since I have been there, and like I said, wasnt aware they had that type of dyno. Just wondered how you knew so much about it. The testing you speak of, is basically what I do, all day every day.

[Scotthatch]

Do you have a link to this?

Sorry they don't like anything they do to leave the building and I can't blame them it's how they make money

It has been years since I have been there, and like I said, wasnt aware they had that type of dyno. Just wondered how you knew so much about it. The testing you speak of, is basically what I do, all day every day.

My best friend here in town his brother works (lives?) At PME

[F-BIRD'88]

..so I switched to 2 500 cfm edelbrock carbs and yes I gave up peak HP but it was a joy to drive so did not care at all

My friend here did the same thing with the Eddy 750 carbs on a tunnel rammed radical high HP big cid Chrysler BB.. Yes the 2x holleys dynoed a bit higher but not enough difference to worry about.
The car drives very well with the 2x 750 eddies.. and GLH . Just like I said it would.
saved a bunch of cash and fuss. The new 650 AVS2 thunder series carbs with annular boosters
are also probably a good choice for this.