Thats not entirely true. An extreme example would be a car that drops from 5000 to 1000 after a shift. No power down there. Its going to somewhat depend on the car as to where the ideal shift point falls. Get the right gear, stall, tires... yea 7k is wasting effort and time.

 

i didnt read the whole thread, so it might have been mentioned already, but its possible to change.

two words:

torque converter.




athough honestly, 1000rpm diff is alot..... on a loose stall that stalled at 5200 in my friends car, it stalled at 5500 after adding over 100 rear wheel hp.

 

If I recall correctly Stock Eliminator Cars with 305 were shifting at 7000 rpm...with TPI. So, it depends.

All of these absolute, Impossible, answers etc. around here

 

agreed on the intake. How much air can you suck through a garden hose? how 'bout an 1/4 fuel line?... you can only get what you give...

- 7k isn't wasting anything. If your geared forand your combination makes power at 7k, then weeeeee haaaa...
My 4161 lb vert(stereo, me 1/4 tank) is a land barge, still knocked down 11.7@130 all motor. Got 20mpg highway and 17 town carbed...I don't think 7k is wasting time or effort.
- Also agree..hp is fuel. The more of it you can burn, the more power you can make. Bigger cubes will rev if you can get burn air/fuel to make it. My dads blown big block turns 9600-10k every pass in the 1/8...

 

On a 305 I could see you getting 6k out of it but that would be a stretch I would think. I've never heard of someone purposefully building/revving a TPI motor with the factory intake to 7k maybe they did but thats nuts...


A torque converter would not make a 1000 rpm difference unless the converter wasn't functioning. Even then the intake manifold has no relation to the gears/gearing of a vehicle. Torque converter might allow it to build revs slightly faster due to more power, but in reality thats only because its not locked up, the ratio's of the engine RPM to speed hasn't changed simply the converter allowing the engine to turn slightly higher RPM. If the converter were locked up there would be no difference. ON a manual transmission car you'd not have any difference unless you had a slipping clutch but thats faulty equipment. Why is it so hard to grasp the fact that an intake manifold does not affect the gearing of the vehicle? Gearing is related to engine speed and mph, torque converters are as well but a properly workin converter would not yield that kind of a difference.

 

Racing is a bit different than normal driving...and Stock Eliminator racing is an extreme.

I was attempting to point out that it is POSSIBLE to have an altered RPM based on something as simple as an intake change, depending on certain variables. Why is it so hard to grasp that it is a possibility? You've already contradicted yourself. I didn't mention anything as far as specifics or specific cases, except that a TC can be affected when power levels change...and its something that needs to be accounted for. Simple as that. Take it for what its worth.
Time to move on...

 

Do you have a link or anything so I can read about this? I would also like to know what kinda power they were making turning a motor that high with that intake.

 

i'm not sure if that was directed to me or not, but i was just saying that any motor can be built to rev and make power to 7K rpms... depends on cam heads intake of course, but the bottom end is where it is. it needs to be built to take that abuse. so a 327 or a 406 can be made to turn 7K rpms.. cubes doesnt really make a difference.

 

and the fact still remains... gears and tire size make the speed and rpms. simple physics stuff. but only in theorectical conditions where there is just engine speed directly rotating the gears... no torque converter slippage or any other slippages

a torque converter will allow slip and thus cuz the engine to change rpms at a given speed. i can crawl 20mph up a steep hill at 2000rpms in first or 2500rpms in first, depends where i put the pedal.. the tq is slipping.

thats the only thing that changes tho that can cause rpms at a speed to change. and the only thing that can cuz how a torque converter acts is the engine power output where cam/heads/intake change that. so basically, a intake swap could cause a power difference and change how the converter acts. which will/could change ur rpms at speeds. but still, gearing and tire size affects rpm vs speed (mph) directly

 

Yeah thats true, from my reading though I gather that shorter stroke motors generally are more durable and can rev higher because it keeps piston velocities down. I've always been under the impression that this was correct. I've read a couple books on motor building and a lot of mags and they all seem to point to shorter stroke bigger bore for higher revving motors. Is this incorrect?

 

Nope, not directed at you... you beat me to the submit button.

 

i dont have it with me but i do have a magazine.. i think hot rod that did a study on hp and torque from short stroke big bore motors vs long stroke smaller bore and also short rod vs long rod.

i have always heard destroked motors or short stroke big bore motors revved higher more easily than others.

i do know that long rods allow for more piston dwell at top dead center or so i read. i'll have to dig that up and see.

as for TPI motors, i'm not sure what they like best... would TPI intake have different power curves for short stroke big bore motors than long stroke small bore motors? what about rod lengths? with the long runners of TPI, you would want to beable to draw in a air intake charge with as little effort as possible. would more dwell at TDC help the combustion process and draw in a charge better than shorter rods? i guess it wouldnt make a difference cuz piston travel is still of the same stroke length

 

Hot Rod's comparison was ok, but they went for same ci, same heads same cam. One motor was short stroke/big bore, the other was bigger stroke/smaller bore. - W/ out heads and cam packages suited for the application, its kind of a wash...

Pro stockers run the big bore, short stroke motors because larger bore takes more advantage of a good cylinder head.(claim made by Warren Johnson). If he says he sees a power difference on the dyno, I believe him. Plus the short stroke lets them buz them, then shift 4 times, maintaining that high hp/high rpm power curve.

later, justin...

 

Well from what I've heard an engine with a small bore is more prone to valve shrouding problems which can have a negative effect on cylinder filling

but as far as fast long tube cars you can go wayy faster than 12s with boost TurboedTPI is running 10.90s with long tubes and boost just food for thought

 

Yeah with FI thats true, but I wanna stay NA.

 

I hear ya I'm an all motor guy myself but you cant argue with results

 

I love motor. Thats why I haven't put that powerstroke turbo on. Something about compression and a big cam just gets my blood flowing... - I kinda like my super powershot.

- My car has sticker that says N/A. It was always there for "naturally aspirated", but since I left it after the bottle I just told my friends it now means nitrous assisted...

 

hahah thats nice

as much as i love the sound of a big rumbling n/a motor, i love the whine of superchargers and the whistles of turbos... the blow off just makes kids go WHOA

 

Ever heard a Kenny Bell Cobra Mustang ..for a mustang its pretty damn sweet

 

Gotta love BOOOOOOSSSST

 

As far as the RPM goes, given the conditions that were being discussed, the TC wouldn't be an issue, and RPMs wouldn't change.

Generally speaking, I suppose it IS possible, but not is this case.