How come so little development of 4V heads for existing V8's

Bos's5.0 · Post by **Bos's5.0** » Sat May 28, 2005 12:45 pm

I know Arao vaporware heads theoretically exist, but how some no one else has decided to make 4V heads for people running "old" school V8's?
Don't they offer much better flow and horsepower potential?

RHC · Post by **RHC** » Sat May 28, 2005 2:09 pm

Because the same performace levels can be reached with 2 valve heads in most small block street aplications with the same degree of reliability and higher levels of performace can be acheived @ less reliabillity with 2 valves such as drag racing and if your going to develop a part there has to be a market base thats afordable and theres nothing afordable about IRL type engines .

ADR · Post by **ADR** » Sat May 28, 2005 6:09 pm

I'm working on a 4V ford right now.....instead of buying one camshaft you buy 4 billet camshafts....32 valves, 32springs, 32valve seats, 32valve guides....etc etc.

Its getting old

Dale

Torquemonster · Post by **Torquemonster** » Fri Jun 10, 2005 7:14 am

I had a tour thru the Arao setup, met the owners and had a 6 month exclusive on the rights to develop a 40 valve V10 Viper head - but it did not pan out for commercial reasons in the end.

I too wonder why the Arao heads have not caught on more - sure they cost more than a hot 2V head - but they offer a far greater power band and sex appeal. Sure you can get a drag race 2v valve head to come close - but it will be useless on the street whereas the 4V head could create a 1000hp naturally aspirated motor that could be driven regularly...

the old problems they had with valvetrain they seem to have surmounted and they apppeared to be reliable to 9500rpm - more than enough for most.

is there something someone out there knows I don't why they never sold more - other than cost? There was an issue where an EX business partner diddled them and cost them a couple of years not being able to use their own brand name - but that's in the past I understand....

There's plenty of money for things people want - I Wonder if perhaps the American market just has not been made aware of the advantages of 4V tech and actually think the hemi is better than 4V

until you've run one it's easy to say a 2v can cut it... well they can only cut it within a very narrow range... the 4v design will absolutely cream the 2V where a wide power band is wanted, plus in all out power - a maxed out 4V will flow more.

The only reason McGee motors never lasted in Top Fuel was that in Top Fuel you need mega strength to handle the explosive power of nitro, and the dinosaur heavy metal of the hemi was strong enough, while the lightweight additional moving parts of the 32V McGee V12 were simply too small to be strong enough for Top Fuel nitro.... still - they were sweet engines and would have been great on gas or alcohol - what a sound hearing 500 cubes wailing at 12,000rpm!

jacksoni · Post by **jacksoni** » Fri Jun 10, 2005 7:37 am

[I too wonder why the Arao heads have not caught on more -

is there something someone out there knows I don't why they never sold more - other than cost? .

How about poor communication and crummy (read none) customer service. I ordered an Arao head (1) for a project I am working on. It probably would have been too big and not work well I have learned (from this forum) but was going to try. About 2-3 month delivery predicted- (for 1 head). At 2 months was told ready to go but on final assembly he said the valve setup wasn't right with the springs being used and needed longer valves. Custom order month or two. Things got sort of back burnered from there and even after being told all parts were in he would not assemble and ship. I waited 6 months to try to get one head before lost patience totally and said wanted my money back. Never heard from him again. Threatend suit (tough from 3000 miles away and would have recovered nothing). Have since talked to another Bonneville guy who said worked for years to get a set of heads and he suggested Arao had this tendency to promise, take money and not deliver. Doesn't exactly do a lot for your business, whether the product works or not.

Post by **SchmidtMotorWorks** » Fri Jun 10, 2005 11:02 am

I have followed with interest some of the 4 valve head projects and they always seem to end without much success. Tried for months to model one for the BBC.

Arao head had some design problems from the photos I saw, there was a water passage on the deck of the head, (not inside the head).

There are head bolts inside the exhaust ports.

Some of the ports photos I saw had port area 2X the size of other 4 valve head proportional to the valve size.

Check the chassis fit too. A four valve head is really wide on the exhaust side compared to a wedge head. When you look at it from the end you really see the genious of the wedge head. Anyhow, no car that I ever had had much extra room where the headers were. I think the arao heads move the headers out at least 1 inch, probably 2 or more.

I would really like to make a four valve head but there are too many unsolvable problems at least for a gen 1 five bolt pattern block. Maybe the LS1 but why? I think the LS1 seems to be doing OK against the Mustang 4V engine.

Arao has a patent (probably not defendable) for his four valve head, the theme of the patent is that the exhaust valves are tipped up to near vertical so that the rockers can reach the pushrods. I think that means the chambers are unusually deep on the exhaust side for a four valve head.

I also wonder about a single rocker opening two valves, the only other place I have seen that tried is on a 4 valve Harley head which also seems to have failed on the market. I don't know if there is a good valve clearance adjusting design that adjusts at the valve end of the rocker. I am thinking maybe some Porshe has this but can't remember exactly.

Oh yah, I saw one at GM but it had hydraulic adjustment built in to the rocker.

Post by **SchmidtMotorWorks** » Fri Jun 10, 2005 11:12 am

The only reason McGee motors never lasted in Top Fuel was that in Top Fuel you need mega strength to handle the explosive power of nitro, and the dinosaur heavy metal of the hemi was strong enough, while the lightweight additional moving parts of the 32V McGee V12 were simply too small to be strong enough for Top Fuel nitro

As I recall the web between the exhaust valves melted out and the rules excluded them at some point. NHRA doesn't even allow valve angle changes in the fuel classes now and is about to limit approved manufacturers.

Ken_Parkman · Post by **Ken_Parkman** » Sat Jun 11, 2005 1:34 am

This is only an opinion, but I think a 4 valve heads, especially DOHC stuff, have "power density" problems, especially in a v-8. The engines become higher, wider, longer, and heavier, and the small gains over current technology 2 valve heads are blown away by the packaging difficulties. It is far more effective to make the engine have a little more displacement in a given size package then pay the penalties of multi-valves. Notice the factories are shying away from that tecnology, again especially on the v-8's. The GM LS and the Mopar engines are remarkably effective pushrod 2 valve engines, and they easily fit into cars. Both of which are much more impressive than the Ford stuff. Sheesh that 4.6 litre engine is huge for it's displacement.

Post by **ClassKing** » Sat Jun 11, 2005 2:02 am

"Power Density" - I like that term.

I think I've got special "density" around my shop sometimes

Called "monday morning..."

Post by **SchmidtMotorWorks** » Sat Jun 11, 2005 2:10 am

This is only an opinion, but I think a 4 valve heads, especially DOHC stuff, have "power density" problems, especially in a v-8.

That's correct, I have wanted to make a compact four valve head for a V8 (or 12) for years, this image is from a SOHC valvetrain layout I was trying to fit around the BBC bolt pattern.

I arrived at this after finishing a DOHC design and going to have CAMs designed and made, one shop after the other told me that I shouldn't use direct buckets.

Anyone ever see Joe Shubecks DOHC V8? It looks nice in pictures that I have seen.

DavidHarsay · Post by **DavidHarsay** » Sat Jun 11, 2005 9:47 am

Looks like a sound design... the simpler the better in my opinion. What sort of valve lift would that geometry be able to support... don't need as much with a 4V that's for sure.

Shim over bucket is simple enough, although it would be nice to have a roller arrangement following the cams also.

OldSStroker · Post by **OldSStroker** » Sat Jun 11, 2005 10:21 am

Ken_Parkman wrote:This is only an opinion, but I think a 4 valve heads, especially DOHC stuff, have "power density" problems, especially in a v-8. The engines become higher, wider, longer, and heavier, and the small gains over current technology 2 valve heads are blown away by the packaging difficulties. It is far more effective to make the engine have a little more displacement in a given size package then pay the penalties of multi-valves. Notice the factories are shying away from that tecnology, again especially on the v-8's. The GM LS and the Mopar engines are remarkably effective pushrod 2 valve engines, and they easily fit into cars. Both of which are much more impressive than the Ford stuff. Sheesh that 4.6 litre engine is huge for it's displacement.

Great observation. As I recall the 4.6L 320 hp Northstar outweighs the alum block LS pushrod engines and has a higher CG. When it went into the XLR (C5/C6 chassis) the hood line had to rise a lot. The 440 hp blown version, a great engine, IMO, is even heavier and taller.

GM LS engines and DC hemis are the least expensive way (both for OEM and gearheads) to get the output and size needed.

Looking at torque per litre at hp peak rpm is a fairly good method of judging an NA engine's ability to pump air. In OEM engines, the LS2 Vette is about 58.4 lb-ft/L, the 6 L Hemi is 59.4, the 5.3L LS truck engine is 56.9, the DOHC 4.6 Ford is 58.0, the 4.6 Northstar is 57.3, the 4.2L DOHC Vortec truck 6 cyl is 57.8, and the 505 hp LS7 is 61.1. BMW does a very good job with their high end stuff at 69.2 for the 315 hp @5400 4.4. The Honda S2000 240 @7800 in a 2.2L is 73.5. These are as installed, of course with mufflers, accessories, etc.

F1 engines are in the 85-90 range(quite a bit from best to worst), Cup engines are in the 82-84 range, Pro Stock closer to 95. These are obviously less mufflers, etc. FWIW, Joe Sherman's 2002 Engine Masters engine was about 81.

My $.02

phoenix · Post by **phoenix** » Sat Jun 11, 2005 11:02 am

I would like to see more development in Desmodromic valvetrains. Ducati
redesigned their current cylinder head by relocating the rocker arm/followers to the outside. The benifits were two fold. 1st, valve angles became shallow, combustion chamber decreased and the overall size of the head shrank, not to mention the simplicity of the design and no valve springs!

phoenix · Post by **phoenix** » Sat Jun 11, 2005 11:24 am

oops! I guess five fold!

Ken_Parkman · Post by **Ken_Parkman** » Sat Jun 11, 2005 11:51 am

An interesting measurement would be torque per weight of the engine, but that would be a tough one to get comparison data on. Bet it would be very telling for the current production engines.

I was in the 2004 EMC with an AMC, and it weighed 540 lbs fully dressed, iron block and aluminum heads, and made 563 ft lbs torque at World Products. That's 1.04 ft-lbs per lb engine weight. Need one of those aluminum 500 inch Rambler blocks, that would get you over 1.5 ft-lb per pound!