The Dodge Challenger Message Board

Posted: **20 Apr 2007 11:23**

Catch what you mean Dave, but you will think it would be all that noticable between his 2 options? Don't forget it's in a heavy car (compared to F1's) which can use the extra torqu the bigger stroke gives. Also as it's more street then strip if I understood correctly.

Rpm wise it's better to have a bigger bore then stroke. If I look at mine last year I crossed the finish at 7100rpm which in my eyes is quit a bit for that big of an engine with only a normal compression ratio and a f/t cam.

All in all, both with give you a good go!

Posted: **21 Apr 2007 14:54**

I think the lighter piston on the 525" (4.31 b x4.5 st) and the longer rod makes quick rpm increase and good dwell with this new ratio crank/rod.

The power secret it's always torque why do you need high rpm if you can get more torque?

John told to me that 4,5 bore is not good partner of Stage V heads.

Posted: **21 Apr 2007 14:57**

72 Challenger (Hans) wrote:I would go for the longer stroke. With that 4.5" arm you will have quit a bit more torque. I even wish I went for a 4.5" crank, it would give me a 572ci then as I already have the 4.5"bore. As for a big bore, this is the 3th year I have it and had not a single problem.

Well, lot of problems, but none were Hemi related. Most of the troubles were tranny related. And now still ignition related.

Anyway, I would go (if money isn't the object) for a 4.5" x 4.5" Hemi making it a 572ci. Otherwise, bigger is still better. With my 4.5" x 4.15" = 528ci combo I've went a 10.64@128 having ignition troubles during the whole run so there's more to come. Oh, this was just on pumpgas, with a flat tappet cam and single 4bbl...so you made the right choice going HEMI.

Hi Hans.

Have you ever seen any white smoke with 4,5" bore?
How much miles did you run in your 528?
Is a MP crate engine?

Posted: **21 Apr 2007 16:06**

plum-crazy wrote:The power secret it's always torque why do you need high rpm if you can get more torque?

You have that wrong. Power is (very basically) torque x rpm. The higher the rpm you make the best torque, the more powerful the engine (HP).

Example. If you made a peak of 500ft/lbs of torque at 2000rpm you would only have a 190 horsepower engine.

If you had that same torque peak at 6000rpm you would have a 571 hp engine.

It is ALWAYS better to make torque at a high rpm. Longer strokes prevent that.

There is always a negative side to everything of course. In this case it means that the higher rpm the torque peak is at, the more you need gears. You also need lower gears in your axle.

Posted: **21 Apr 2007 16:42**

I would go for the longer stroke. Better "grunt" off the bottom end and with those heavy breathing Hemi heads will pull like crazy on the top end as long as the cam is large enough. I also would use a solid flat tappet or solid roller,(preferred) with circle track valve springs. I always thought the Stage V heads,(Eric Hansens company), with the 2.4 Intake valve was specifically designed for large bore engines 4.310 minimum?

Posted: **21 Apr 2007 17:36**

Sorry Dave. Sometimes is hard for me to express myself as good as I want.
I just want to say if you get enough torque at wide range of rpm you don't need to go to high rpm.
Of course high torque at low rpm is only for towing :wink:

But I need to choose between 484ci with 4.15 stroke and 525ci with 4.5 stroke and BOTH with the same bore , 4.31.

I thought large strokes have difficult to arrive to 6000 rpm, but a guy who owns a 525 told me that this combo uses lighter pistons and this allows the engine reevs quicker in spite of 484 with shorter stroke but heavier pistons, about 20% more weight.

Posted: **21 Apr 2007 17:45**

airfuelEddie wrote:I would go for the longer stroke. Better "grunt" off the bottom end and with those heavy breathing Hemi heads will pull like crazy on the top end as long as the cam is large enough. I also would use a solid flat tappet or solid roller,(preferred) with circle track valve springs. I always thought the Stage V heads,(Eric Hansens company), with the 2.4 Intake valve was specifically designed for large bore engines 4.310 minimum?

I think there's several heads configuration from stage V, but I'm not sure.
I trust on John, and if he uses Stage V heads from 2000 year with this bore sizes he maybe have his own reasons.
I read somplace the article that he built his 500 hemi engine on 2006 summer. :shock:

Posted: **21 Apr 2007 22:53**

I would trust John to plum crazy. BTW, every time I want to go to StageV engineering site, they say under construction since Aug. 01! Those heads are awesome! Whatever you decide it wont be wrong! 484 or 525 Hemi is like Paul Raymond or Hugh hefner deciding on whats for dinner that night, dark meat or light! :biggrin:

Posted: **21 Apr 2007 22:55**

I would trust John to plum crazy. BTW, every time I want to go to StageV engineering site, they say under construction since Aug. 01! Those heads are awesome! Whatever you decide it wont be wrong! 484 or 525 Hemi is like Paul Raymond or Hugh hefner deciding on whats for dinner that night, dark meat or light! :biggrin:

Posted: **24 Apr 2007 11:07**

plum-crazy wrote:
72 Challenger (Hans) wrote:I would go for the longer stroke. With that 4.5" arm you will have quit a bit more torque. I even wish I went for a 4.5" crank, it would give me a 572ci then as I already have the 4.5"bore. As for a big bore, this is the 3th year I have it and had not a single problem.

Well, lot of problems, but none were Hemi related. Most of the troubles were tranny related. And now still ignition related.

Anyway, I would go (if money isn't the object) for a 4.5" x 4.5" Hemi making it a 572ci. Otherwise, bigger is still better. With my 4.5" x 4.15" = 528ci combo I've went a 10.64@128 having ignition troubles during the whole run so there's more to come. Oh, this was just on pumpgas, with a flat tappet cam and single 4bbl...so you made the right choice going HEMI.

Hi Hans.

Have you ever seen any white smoke with 4,5" bore?
How much miles did you run in your 528?
Is a MP crate engine?

Have no idea on the miles I've put on it so far as the speedo is not working. But the guess would be around 2500-5000miles and about 50runs down the strip.

So far not a single sign of smoke or any other bad thing.

I got the short block through Barton and finish the build over here using 65 alu heads and the other stuff we ordered. Only thing I would do differetn if I could do it again is get a 4.5" stroke crank. Other then that it's a blast to drive.

Posted: **24 Apr 2007 15:36**

Nobody asked, but here's a "cute" little 451 build, cheap, easy, doesn't "piss & moan", has great street manners on low-octane fuel for street driving, and still has plenty of motivation for heavy old cars.

We don't do many of them anymore, as everybody wants 500 and bigger, so these get "overlooked", but did one recently for a "poor guy".

400 block/451, with Edelbrock heads, and small solid Flat-tappet Camshaft

Just something to thing about, NOT trying to confuse the issue

Posted: **24 Apr 2007 18:14**

Nice Flat Torque curve there! Impressive with only a 750 Holley.(Is it showing a too lean condition?) :thumbsup:

BTW, is that the 3.75 crank,(400 mains) with 6.768 rods? I am looking at using a 3.915 4340 Crank and 6.535 Rods and 1.485 Pistons for 470 cubes at a Zero Deck shortblock on my 400/470 project. Nice Work

Posted: **25 Apr 2007 3:15**

Yes, that is the 3.75 stroke crank with the 6.76 stock rod, in the 400 block.

I prefer the higher ratio engines, over cubic inch, for the BB mopar stock port windows.

I even go for the 7.15 rods in the 540's, just personal preferences.

Posted: **25 Apr 2007 9:22**

Nothing wrong with that! BTW, I noticed the Air Fuel Ratios and the BSFC#s is that carb too lean? Wonder what the H.P. would be with a Pro-Systems Holley 950 or even a 1050!

Posted: **25 Apr 2007 15:06**

I just think it needs a Holley 850 and richer jets. Then it would be a damn good consistant mid-low 11s engine in a heavy Challenger like mine. :nod:

Posted: **25 Apr 2007 18:31**

dave-r wrote:I just think it needs a Holley 850 and richer jets. Then it would be a damn good consistant mid-low 11s engine in a heavy Challenger like mine.

No doubt about it! BTW, have you ever seen an A/F ratio that lean?:thumbsup:

Posted: **25 Apr 2007 18:33**

airfuelEddie wrote:
dave-r wrote:I just think it needs a Holley 850 and richer jets. Then it would be a damn good consistant mid-low 11s engine in a heavy Challenger like mine.

Posted: **25 Apr 2007 18:35**

No doubt about it Dave, BTW, have you ever seen an A/F ratio that lean? I hope FC doesnt take this a slam on his "bullet" it's really a nice piece. I hope mine turns out as well.

Posted: **26 Apr 2007 13:34**

Hi Follicly Challenged.
I was looking a RB 451 from Indy, I thought it was a good combo and they promise 550hp at 5700 using a RB block.

Near your engine, practically the same.

It's a wonderful flat torque curve as ays airfuelddie.

Finally I decided to install the hemi, I'm getting budget for it almost one year, since I sold my 440 on june 2006.

Once on the hemi way I try the higher stroke vs. higher bore.

Posted: **26 Apr 2007 13:39**

I'm not on the wave like you guys but Indy is selling their 426-451 wedge engines with a mighty 750 demon.

Where do you see that is necessary bigger car on FC engine?
There is some place on this dyno too see that's lean mixture?

I need to know, once I know more thinks I'm sure that I know nothing!

Posted: **26 Apr 2007 13:46**

Looking at dyno I see the jets size and it seems too small for a 750.
This is a specs chart from SPEED demon.

CARBURETOR SIZE 575 650 750 850 850 AN
MAIN JETS PRI : # 62 # 70 # 76 # 85 # 80
MAIN JETS SEC: # 70 # 78 # 83 # 93 # 85

Posted: **26 Apr 2007 15:49**

A demon 750 flows the same as a Holley 850. Something to do with the way they measure them.

Initially it was a way to make their carbs seem to make more power than the Holleys. But they just flow more. I think they wet flow them.

Posted: **26 Apr 2007 16:07**

plum-crazy wrote:There is some place on this dyno too see that's lean mixture?

Want maximum hp? Aim for 13:1 air/fuel-ratio! (From: http://challenger.mpoli.fi/forum/viewto ... 6602#16602 ) Right?

Posted: **26 Apr 2007 20:27**

At 14:1 Ratio the "mix" is leaning out. Wonder if they used EGT couplers on each exhaust port. The really only accurate way to tell is with EGT thermocouplers in the exhaust pipes. Too lean will burn valves and more importantly the pistons and scuff the cylinder walls with the skirts. As temps approach 1400 degrees, very bad things can happen! Lean is Mean! :s016:

PlumCrazy the 451 INDY engine is based on a 400 Block not an RaisedBlock or RB block.Deck Height RB Chrysler Block=10.725 Deck Height B Block=9.980. :thumbsup:

Plum Crazy you do understand why the 400 block is preferred don't you? The best book for the enthusiast on Chrysler B/RB engines that I have ever read is Chuck Senators Book Big Block MoPar Engines. It cuts through the aftermarket "hype" and explains fully. The dynamics and Racing the engine itself. The info on Cylinder Heads and why they work so well on certain Packages is priceless! It covers Wedge Head engines only. Crossflow,(hemis), behave a little differently as they have sewer sized intake ports and agressive timing.

Posted: **26 Apr 2007 23:52**

OK, afeddie.
I checked it and the rod size is for 400 block.

Posted: **28 Apr 2007 5:49**

Finally will be a 525", 4.31 x 4.5, hydraulic cam, stage V heads, stage V dual intake with 650 holleys, 10:1 compression.

Maybe 650hp @ 6000 - 620 lb/ft 4000-4200 rpm.

Once installed we think about other goodies to make a good ET but firstly I need to handle it.

Twelve loooooooong weeks are needed to build it, then shipping to spain.

Maybe a present for chistmas? :roll:

Posted: **28 Apr 2007 12:41**

Sweet!

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