stroked 409 RPM limitation

61 Bubble

Well Known Member
#41
Ya, dyno's and flow bench's are always sceptical??? I ALWAYS see "on a CONSERVATIVE dyno" or "on a STINGY flow bench" when people talk about either. I have NEVER seen someone post "I made X amount of power on the dyno, but we all know his dyno reads high, so who really knows?"

There are 3 dyno's in my area that I would use. Fj Smith the SuperStock chasses legend. Konigshofer Motorsports, MMPS guys for YEARS and another guy. I have seen motors on the variation of the 3 and there very close. PLUS we have seen those #'s from them run on another ULTRA high-end Mustang chassis dyno. They run the 1/4 mile on it, and usually shows close on the power, and cars repeat there Mustang dyno ET's at the track within .10.

I also seen a valve cover gasket cost 30Hp? My chew Chief, Konigshofer, had is HS 360 inline headed for on there to break in. We made a pull, reset the valve, and instantly LOST 30.8Hp. A gasket had been sucked in.

So little details need to be checked all the time.
 

jdk971

Well Known Member
Supporting Member 6
#42
educate me
i can see high rpms maybe for road race. but for vehicles we drive, not you pros who drag race, why do you need to spin it over 6k. isn't most
hp made below 6k and the torque spent? i have always shifted by ear. except for my solid lifter sbc i usually shift around 5200 the vette
around 5800. i am not a mechanic i just drive them. jim
 

409 lever

Well Known Member
Supporting Member 2
#43
how does a valve cover gasket cost 30.8 hp? do you mean a intake gasket? there are 4 dynos within 10 miles of me,,, they all lie. the only guy I have personally seen that has a clue is steve baker of baker carburation in mechanicsberg PA, he is a really sharp dude. 7500 rpm is not a street engine in any way, shape or form.
 

61 Bubble

Well Known Member
#44
Jim, you have it a bit wrong. "MOST" well engeerred engine will have more tq then hp below 5252, and will make more hp then tq over 5252. My 498 BBc make 829 ft/lbs at 8200, but also makes 1263hp at the same 8200. Now this is all motor, no nitrous or blowers/turbos.
We see hp go up as a direct relation to RPM. In other words, you need RPM to make hp. That is if the engine is designed for it. Like I said, I don't think, after doing my due-diligence, that running these W motors at the higher RPM is not recommend.

Jim, today technology, motor are spinning higher and higher. Most engine are now designed to run 7500 RPM and higher. They have heads, cam and intakes to take advantage of this. The older designed W motors don't seem to want that.

John
 

61 Bubble

Well Known Member
#45
how does a valve cover gasket cost 30.8 hp? do you mean a intake gasket? there are 4 dynos within 10 miles of me,,, they all lie. the only guy I have personally seen that has a clue is steve baker of baker carburation in mechanicsberg PA, he is a really sharp dude. 7500 rpm is not a street engine in any way, shape or form.
30 hp loss, vacuum leak!!! I would have never believed it myself. But I did see it with my own eye.

That's sad that the dyno' sin your area are that way!
 

409 lever

Well Known Member
Supporting Member 2
#46
so it was an intake leak, not a valve cover,,, correct? 30hp from a intake gasket is totally believable.
to have an engine fill 8 cylinders with a cubic inch around 450 at 7500rpm would need a pretty stout set of cylinder heads, probably in the 350cfm plus area. 5252 is the conversion factor of torque to horsepower. a dyno measures everything in torque and divides that by rpm and 5252. the 5252 rpm has nothing to do with how the engine is engineered all engines make the same torque and horsepower at 5252 rpm, everything from a Tecumseh to a Top Fueler, this factor never changes.
 

61 Bubble

Well Known Member
#48
Must have been valve cover, They reset the valves. 30 hp? Who knows, maybe they set the valves wrong.
YES it was solely the result of a valve-cover gasket. These style engine need to be sealed up tight. Think of it this way, if there not sealed, what is the use of the vac pump? many get 25 or so Hp from the use of a vac pump on engines that are designed for it. this was I recall at about 9600 RPM. Motor made enough power to push this 2800 lbs Mustang to 8.40's.

This team, who just happens to be the crew chief on my car as well, has been in Pro Stock racing since 1991. I highly doubt the valves were adjusted wrong? If so, there would have been a lot more damage at 9600+ RPM then just a lose of Hp. They changed out the gasket, didn't touch the valves, and power came back. But we knew that as we seen there was no vac on racepak.
 

jim_ss409

Well Known Member
Supporting Member 5
#49
Yeah, I don't think the guys were thinking about engines that use a vacuum pump.

They're widely used on race engines these days. I gather they can easily add 30 hp to a high rpm engine.
The vacuum helps the rings seal and allows the use of thinner and lower tension rings.
They say there is even a small advantage in less crankshaft windage because the crank if spinning in air that's less dense.
The engine we got from Joe Sherman came with a vacuum pump and we also put one on the aluminum engine in the Pontiac.
Dry sump oiling systems also pull vacuum.
 

61 Bubble

Well Known Member
#50
the 5252 rpm has nothing to do with how the engine is engineered all engines make the same torque and horsepower at 5252 rpm, everything from a Tecumseh to a Top Fueler, this factor never changes.
Really?? My whole engineered engine concept was brought up with a discussion with George Bryce on YB, along with other certain engine guys.

This is what George posted, DIRECT QUOTE:

" The 500 inch PS NHRA engines run way higher up than where peak tq is also.
ALL engines have the same horse power and the same torque at 5252 RPM.
Well designed engines have more Torque below 5200 rpm than the HP.
AS well designed engines have more HP than TQ after 5200 RPM."



I have a 706 BBc. These engine, that "used" to be the bad engine in Pro Mod 10 years ago, do not always follow those last 2 lines? Many make more peak tq then peak Hp. These "grunt" engine were, and are running fast to this day. This was just the "bigger is better" way of thinking. Yet doesn't follow the norm of well designed! I never once said anything about engine NOT making the same at 5252???

409 lever, your premise on 350 CFM to fill 450" motor at 7500 could well be correct, that I'm a little unsure of. Maybe that's why most of these 690 headed '09 strokers are RPM limited?? These reason for this thread? It could very well be that anything less the Z11 heads on these motors ( that are say 430" or larger) is the limiting RPM factor. Diminished returns do to the intake track NOT being able to properly fill the cylinder???

So it might not be a piston/rod/crank or even block issue for the lower RPM '09's. Just maybe these induction can support 47?+ inches????

Thanks 409. Got me thinking!!!!!
 

dm62409

Well Known Member
Supporting Member 11
#52
Quote; "409 lever, your premise on 350 CFM to fill 450" motor at 7500 could well be correct, that I'm a little unsure of. Maybe that's why most of these 690 headed '09 strokers are RPM limited?? These reason for this thread? It could very well be that anything less the Z11 heads on these motors ( that are say 430" or larger) is the limiting RPM factor. Diminished returns do to the intake track NOT being able to properly fill the cylinder??? ".

You just found your answer.
 

61 Bubble

Well Known Member
#53
I would regularly spin my 474 to 7500 on the street. Did it for years. After finding out these heads are the limiting factor most times, and peak power is usually around 6500, I now shift 6200 or so.
Yep, see it now. I had the "mindset" that the limit was in the short block somewhere? Like piston weight/design being the issue. Seems that that is not true?

Brian, what intake do you run? If you know your peak Hp is at 6500, does it fall off sharply, or holds on a bit then tappers off? If it holds on and tapper, I would run it a bit OVER the 6500. Most our stuff runs 400 RPM over max Hp RPM.

Thanks, guys. I will talk with my head guy and see what he thinks we should "try"?? Sometimes that can get pretty $$$. Porting, valves, back cuts and angles. Jim posted he "thought" his Sherman Eddys were about 329, Nick (BOSSMAN) got about 332 out of his. Nick DID a 606Hp pump gas 475 with hyd roller and the Eddy intake too. I see Brain's Eddy's has a bit more flow at 342/344 at .700/.750. Now BWR racing heads, one could easily do 700Hp.

So, look for a 650/675Hp motor with 690 heads. Or go with some Alum aftermarkets and add about 75Hp???

SEE I DID LEARN SOMETHING TODAY. THANK YOU.
 

61 Bubble

Well Known Member
#55
Man Skip, our motor "look" the same. I have ported 690's though.




As for that dyno sheet, I would be looking 67-6800 as a shift point. But still some nice numbers. Pretty flat curve both Tq and Hp.
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61 Bubble

Well Known Member
#57
Dave, that sheet is for standard or raised port head??? Not mush good without an intake on there to choke it off and really see what air the set-up moves? With those numbers, 7200+ should be quite do-able IF the intake can get close to that???

Was at my engine shop yesterday. Talked about a bunch of stuff for BBc. We took a stock "sorta" cleaned up 840 sq port 427/425Hp head and my cheapie aftermarket head that made 890Hp on a 540. But I also took 5 intakes I have to see how the heads flow and what happens when each style intake is put on. Once we get a hand on the sq ports, I'm going in with my 215 '69 427/390Hp oval that are ported. I have 4 intakes for that. Just need to see what is what and where to set these motors up.

Now since this is the 348/409 website. We touched on a few things. It will be a slower process as this is FAR from the mainline that a business need to survive. They are redoing "mostly" Vipers, Vette's and muscle car stuff. Getting into more of the exotic market like BMW's Porsche and Ferrari's. the funniest story I was told is about a BMW 750Li. In the 1/4, it beats modified Z06 Vette and other muscle cars!! BUT will also out run most of the exotics on a road course!!!!

Back to the '09 stuff. Seeing that these engine like the lower RPM's for the most part, we talked about a few different ways to go. EVEN to the point of getting a set of pistons like Aubrey did. 4.25 stroke, .068 over bore, lightened gas ported and 14.5 to 1's. We wouldn't hesitate to use those slugs in a semi-daily driver with alum heads. Just don't know if we can control the detonation with steel heads. One thing I noticed with MY 409/476. I run the .714 solid roller (I think as per Jim) cam. Aubrey doesn't even offer one on his site. But we have hyd rollers that will work in the operating range that people are talking about.

By the way, I just want it know that I DO NOT like this Edelbrock 2X4 intake I have on my '09!
 

Iowa 409 Guy

Well Seasoned Member
Supporting Member 10
#58
Dave, that sheet is for standard or raised port head??? Not mush good without an intake on there to choke it off and really see what air the set-up moves? With those numbers, 7200+ should be quite do-able IF the intake can get close to that???

Standard port heads with my edelbrock intake. It would be interesting to know how they flow together. I can't find the sheet for my cam, but it seems like hp and tq were about done at 5,800 or so. If I remember right I shift at 6,200. Sure, I could spin it harder, but I don't see any gain to be made with my setup. Also, I plan on getting down to the 11:50 et this year, and I ain't going with a rollbar.
 

61 Bubble

Well Known Member
#59
My 600ish HP 470ci with ported E heads and ported intake flowing 304cfm @28" through the intake and head (got to look at both not just raw heads unless a real free flowing intake like the new one out)was not a high rpm motor. It is 10.25:1 pump gas solid roller 251/251@ 0.050
This what Skip's ported Eddy heads do through the intake!!! 304@28"...
 

61 Bubble

Well Known Member
#60
Standard port heads with my edelbrock intake. It would be interesting to know how they flow together. I can't find the sheet for my cam, but it seems like hp and tq were about done at 5,800 or so. If I remember right I shift at 6,200. Sure, I could spin it harder, but I don't see any gain to be made with my setup. Also, I plan on getting down to the 11:50 et this year, and I ain't going with a rollbar.
Dave, that's the common RPM that most of the people I know us AS LONG as your Hp doesn't fall off to drastically. PEAK +400 seem about the norm, so your correct, no need to spin higher.

BTW, I have 2 other cars for the street. One has a 8.50 cert cage, the other is 25.4 good to 7.50's. So like you, I'm trying to go "cageless" in this one.
 
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