Who Thinks OHCs are a good idea for V engines?

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Originally Posted By: Trav
The OW43 was dyno HP. The L88 had 435 published HP but dyno at over 524 HP and a 429 twisted hemi with minor mods pulled over 800 HP on the dyno. Some of those old engines were a lot more powerful than published HP numbers and were much easier to tune for more HP.

http://www.hotrod.com/articles/ccrp-0910-chevy-l88-427-engine/

https://ateupwithmotor.com/terms-technology-definitions/gross-versus-net-horsepower/


I only like the drag race calculators for "real" hp. My 1970 Chevelle was rated at 450 hp but never even broke into the 12's with mods. You can blame some of that on tires but the fact remains that the "small" 6.1 hemi I have now easily runs 12's with more weight! Only rated at 425 hp. But needs 460+ to run the et's it does.

Sorry, but old experienced engine experts also agree that the Hemi is more powerful today with less displacement. And the dragstrip proves it. Net vs. gross is a huge difference.

I've heard all the reports of L88's and such making unreal dyno numbers, but these are far more rare and once again the dragstrip results really don't seem to back up the huge hp claims. In about 1973 I saw a stock L88 Vette run in FL in good D/A and it could get some low 12's at like 115 mph. The guys you read about at the FAST events are running carefully balanced and blueprinted engines. They may be stock but they were never so carefully assembled at the factory.

I have personally seen the results of accurate blueprinting and assembly tweaks on my friends 428 Mustang. It had over 50 more hp with no other work done!
 
Originally Posted By: Trav
The OW43 was dyno HP. The L88 had 435 published HP but dyno at over 524 HP and a 429 twisted hemi with minor mods pulled over 800 HP on the dyno. Some of those old engines were a lot more powerful than published HP numbers and were much easier to tune for more HP.

http://www.hotrod.com/articles/ccrp-0910-chevy-l88-427-engine/

https://ateupwithmotor.com/terms-technology-definitions/gross-versus-net-horsepower/


Basically, the big difference between Gross and NET is that NET is tested with accessories and to some degree, how the engine will be when fitted in the vehicle (depending on which version of the standard you are looking at). This can mean ~%30 difference in power between the same engine measured using the two different systems. As you can see from that hot rod article, that engine was spinning no accessories and had open headers. Fitted to do the current version of the NET test, it would have a full factory exhaust system, alternator, A/C compressor, water pump, power steering pump....etc. All of which take power to turn.

This is why engine dyno numbers lose a lot of their relevance when you are comparing them to modern numbers cited by OEM's, which are all SAE NET. Look at trap speed at the same weight to get a better idea as to what something is really making. If an E39 M5, at north of 4,000lbs makes 398HP SAE NET and traps 118Mph, and an L88 Corvette makes "524HP", weighs 1,000lbs less and traps 115MPH, one can pretty logically conclude that there's a rather significant difference between the numbers derived from the two rating schemes.

Put both cars on a Mustang dyno to see what they make at the tires as an equalizer. I believe the reason this is not done more often is because generally the numbers when obtained this way are far less impressive.

HotRod also tested a bone stock 302HO on their dyno at one point, the engine that was rated at 225HP SAE NET from Ford:
http://www.hotrod.com/articles/ford-302-v8-engine-buildup/

First run on the dyno was 278HP/315lb-ft. That's 24% higher than Ford's SAE NET rating.

So if we reverse this to take your HellCat example into context, many of them are dyno'ing 660-670 to the tires. Using the good 'ol 15% RWH figure, this gives us 765HP SAE NET flywheel. A bit higher than what Dodge rates them for. Then, let's use our 24% we just observed using our 302HO example: That gives us 948HP SAE GROSS. That's huge.
 
Originally Posted By: Silk
Originally Posted By: bunnspecial
Granted the number of B blocks is pretty limited in the US compared to the UK and Down Under, but neither the one in my car nor the one sitting on my garage floor right now have hydraulic tensioners. In fact, there's no chain tensioner at all-it just loops around crankshaft sprocket and camshaft sprocket.


After a bit of research, my memory isn't slipping, the BMC B series engine has a hydraulic cam chain tensioner.

$_57.JPG



Thanks-guess it's been a little while since I looked at one too.

I was about to pull the timing cover off my parts engine last night
smile.gif
. The guy who sold it to me said he'd put a camshaft and new timing train in the engine when he rebuilt it 5 years ago, and if they're better than the ones in my engine I should probably swap them(the engine went in a car he built for a lady, and came out when the engine came in with a cracked block). Granted, I hate to go to that much work and not use all new parts, or at least a new camshaft.
 
Originally Posted By: SteveSRT8

Don't forget those old SAE gross hp numbers must be reduced at least 20-30% to compare to SAE net hp ratings. Not even close to Hellcat territory.

And to Roofless VW: Have you seen the production numbers you speak of? There's millions of LS style V8's sold every year! let's see the production numbers for those 5 valve per cylinder vehicles!


This was the case most of the time.

However, as insurance companies glowered at the HP #, there were a number of engines that met or exceeded their gross numbers. Sometimes exceeded by very wide margins.
 
They made that or more...though the 425HP rating might have been close. IIRC, the 425HP was at 5000RPM. The catch? a 426 Hemi is still pulling past 6000RPM!
 
Originally Posted By: DoubleWasp
Originally Posted By: Trav
Sure the new Hemi is fast but the old ones were no slugs either. So let the excuses begin.

http://www.streetmusclemag.com/news/68-hurst-hemi-dart-l023-is-this-the-worlds-fastest-muscle-car/


The horsepower rating on the 426 Hemi was a lie. They made nearly 500hp in real life.
smile.gif



I know that and that's the point, all this talk about this one and that one being more powerful when the truth of the matter is some of the numbers seem like they were pulled out of a hat.
Stock the old muscle cars were slower than today's but they didn't have to be, with not too much work one could easily pull decent times and some did.

For a 1968 car with a window sticker on it you could buy at a dealer the Dart was a real screamer even by today's standards.
19.gif
 
Originally Posted By: Jarlaxle
They made that or more...though the 425HP rating might have been close. IIRC, the 425HP was at 5000RPM. The catch? a 426 Hemi is still pulling past 6000RPM!


the Race version-cross ram hemi and dart of 68 were about 600 hp with qrt mile times in the 11's!!
 
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Originally Posted By: andrewp1998
Originally Posted By: Jarlaxle
They made that or more...though the 425HP rating might have been close. IIRC, the 425HP was at 5000RPM. The catch? a 426 Hemi is still pulling past 6000RPM!


the Race version-cross ram hemi and dart of 68 were about 600 hp with qrt mile times in the 11's!!



Yes, and the TASCA Super BOSS 429 Mustang was a 10-second car on polyglass tires. However those aren't your run of the mill versions of those cars and engines.

A STOCK HEMI Charger was a 13 second car off the showroom floor. And we aren't talking low 13's.

If you've never seen the HorsepowerTV muscle car shootout, it is a good watch.

Cliff notes, the HEMI Challenger at 3,800lbs (significantly lighter than a current SRT Challenger) ran 14.0 @ 100.79Mph. The BOSS 429 ran 13.74 @ 101.4. Those were the two fastest cars in the shootout. These were all showroom stock.

I've observed similar real world results with a showroom stock Charger at a local strip. Car ran high 13's (13.8 IIRC) at around 100Mph. That trap speed is not a 500HP trap speed. Not even close. My '87 GT T-Top, which weighs about the same, trapped 99.9Mph with 225HP (SAE NET). It also ran high 13's. An aluminum driveshaft and underdrive pulleys and I was trapping 102.

In comparison, the current Challenger Scat Pack with the 485HP 392 sporting a curb weigh of 4,235lbs was piloted by Motortrend to a 12.6 @ 112.3Mph.
 
Originally Posted By: Trav
Sure the new Hemi is fast but the old ones were no slugs either. So let the excuses begin.

http://www.streetmusclemag.com/news/68-hurst-hemi-dart-l023-is-this-the-worlds-fastest-muscle-car/


That's essentially the equivalent of the TASCA Super Boss though, that's a race-ready spec car with no interior and is probably 2,500lbs. When talking about the stockers, sold off the showroom floor, they were not providing that level of performance, and were significantly lighter than modern examples.

The HEMI, BOSS 429, GM 427, Ford 427 "Cammer"..etc. All offered tons of room to improve upon in stock condition. Big bore, big displacement, tons of potential. But as delivered, due to the nature of the SAE Gross rating scheme, the numbers provided by the OEM's were quite generous when compared to the modern SAE NET rating scheme. And it is entirely relative to what the engine is fitted to as well. Slapped in a stripper Dart with long tubes and no accessories, performance realized is going to make the gap between GROSS and NET much closer than it would be if that comparison was in a Challenger with full exhaust and accessories. Hence my earlier example with the Ford 302, which further demonstrates the result of that difference. That's the nature of the beast, and that's entirely WHY the rating scheme was changed, to be more representative of the actual operating conditions.
 
Originally Posted By: Trav
Thats cool as [censored], nice to see a non LS swap for a change.


I know right?! Would love to see one with the 392 plopped in it, thing would FLY!
 
It sure would but I am not sure you could open the doors after running it hard without some serious undercarriage stiffening. On the other hand it might want to jump in the bushes every chance it got.
lol.gif
 
Originally Posted By: DoubleWasp
Originally Posted By: SteveSRT8

Don't forget those old SAE gross hp numbers must be reduced at least 20-30% to compare to SAE net hp ratings. Not even close to Hellcat territory.

And to Roofless VW: Have you seen the production numbers you speak of? There's millions of LS style V8's sold every year! let's see the production numbers for those 5 valve per cylinder vehicles!


This was the case most of the time.

However, as insurance companies glowered at the HP #, there were a number of engines that met or exceeded their gross numbers. Sometimes exceeded by very wide margins.


That would be my favorite motor the DZ302 Chevy. It was officially rated at 290 HP but really made closer to 350-380 gross at the flywheel. Strictly written that way for insurances...
 
Originally Posted By: SteveSRT8
Originally Posted By: DoubleWasp
Originally Posted By: SteveSRT8

Don't forget those old SAE gross hp numbers must be reduced at least 20-30% to compare to SAE net hp ratings. Not even close to Hellcat territory.

And to Roofless VW: Have you seen the production numbers you speak of? There's millions of LS style V8's sold every year! let's see the production numbers for those 5 valve per cylinder vehicles!


This was the case most of the time.

However, as insurance companies glowered at the HP #, there were a number of engines that met or exceeded their gross numbers. Sometimes exceeded by very wide margins.


That would be my favorite motor the DZ302 Chevy. It was officially rated at 290 HP but really made closer to 350-380 gross at the flywheel. Strictly written that way for insurances...


Similar to the venerable BOSS 302, which I believe carried the same "rating"
wink.gif
 
Originally Posted By: Trav
It sure would but I am not sure you could open the doors after running it hard without some serious undercarriage stiffening. On the other hand it might want to jump in the bushes every chance it got.
lol.gif



Yeah, subframe connectors would be a must, LOL! I remember how much twist my old T-Top had with just a warmed over 302 in it, hahahha
grin.gif
 
Originally Posted By: OVERKILL

Similar to the venerable BOSS 302, which I believe carried the same "rating"
wink.gif



Yes. In the old daze at the strip I watched the Z/28's with the 302 run nearly identical times with the Chevelle SS's with a 396. Both the 325 hp and the 350 hp versions.

But they couldn't quite keep up with the 375 hp versions of the 396.

My BIL has an all aluminum 396 in a basket at his shop, allegedly worth a lot to the right person...
 
My two cents is that large displacement pushrod engines are physically much smaller than OHC examples and thus are more easily packaged in a passenger car. With the enormously tall hoods of today's pickups, there would be no problem with those applications either way.
If GM really thought that there were performance benefits to be had with an OHC V-8, then wouldn't they build one?
Does anyone seriously want to argue that Ford has engineering resources exceeding those of even New GM?
Both of these methods of valve actuation are very old, so neither can be said to be advanced tech in any way.
GM goes with the compact pushrod designs while Ford is married to its cammers. Same destination, different roads.
 
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