HIGH PORT CROSSFLOW HEAD

[CHESTNUTXE 7,299]

Last few weeks i have been thinking about how they chopped the clevo heads back in the day im wondering would doing this to a crossy head have any benefit ? has anyone ever tried this ?

[matt_lamb_160 252]

I doubt it, but yeah a straighter port must be of benifit. Do you have examples of the Cleveland heads that have been chopped to achieve this?

 

[deankxf 20,266]

where are the water galleries? you may find the cost of development is dearer and not justifiable compared to just a decent port job 

[CHESTNUTXE 7,299]

i have been thinking a bit since yesterday the iron clevo head bent at a bad angle ,so they cut it and used billet alloy high port plates,but i had a look at a crossy head today and figure its probly not worth doing as the exhaust runs almost straight out as it is,but saying that the mod would only work at very high rpm,and they were chasing every horsepower back in those days,nowa days you can buy a spastic alloy head off the shelf with raised runners.

[CHESTNUTXE 7,299]

but hey lets do it,i will chase a crossy head and drop it down at ol m8 s machine shop his eyes will roll.

[slydog 7,873]

Jason Murphy and couple other started/tried but stopped just like clevo guys did when they found they could use filler instead.

The cost of the work involved for the potential outcome of predicted cfm demand outweighs the benifits.

CFM demand is the first question you should ask before building a engine and I would be extremly suprised if any one with a xflow on here needs more than a stock ported xflow head can give. They can work awesome if ported correctly but as the saying goes,you wont know if you dont try so knock your self out.

[bear351c 10,270]

Port tongue plates, fitted as part of a gasket.

 

Port filler used to reshape the hole...

 

 

Port plate, heavy machining required to install.

 

[CHESTNUTXE 7,299]

thanks bear 

[gerg 10,871]

I'll chime in here with my 2c:

Clevos were hampered by the need to squeeze the medium-block V8 shape into what they called "compact" cars in the states, one of the major hurdles was tucking the exhaust manifolds under to clear the shock towers in the falcon/fairlane/mustang engine bay. The only practical way to do this (but still have adequate performance) is to curl the exhaust port downwards sharply to meet the tucked-on manifold ports.

This was fine at the power levels that the road cars came with, but as race horse power kept going up, this port design was becoming more and more of a restriction. The 4V head is actually worse in shape than the 2V, despite having a bigger cross-section.

As the 4V was the only head that anyone bothered to race with, it was why port plates came about. Even then, they were a race-only addition as long-term use would give sealing issues, etc.

The crossflow head is not hampered by such space requirements, so the ports are nice and straight. They can keep velocity up but as Sly mentioned, still flow more than enough for what the engine can handle. The biggest restriction on the pushrod 250 would be available valve size rather than the port, due to the long stroke/small bore arrangement.

This is why the OHC, with its Hemi arrangement, could fit bigger valves and make more power with all else being equal.

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[ando76 4,354]

As Rob pointed out, others have tried it and they didn't achieve results as good as the cylinder head in the below flow bench screen shot.

No high port, no massive port window. Just smarts from 2 passionate people. Others have achieved higher flow and good on them.

Reality is that no one will pay for this head. There is only a very small number of enthusiasts who are pursuing making power from these things. If you can do the work yourself - or a prepared to pay the price to someone who can - the sky is the limit







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[slydog 7,873]

Hey Ando think you put the wrong pic up cos we can all read the txt.

[ando76 4,354]

Nah. That's the comment that's readily able to be seen on the business page. I have nothing to hide. 

[slydog 7,873]

Doesnt sound small by reading the txt. Then cotton wool in a port you know no one on here can or would copy anyway. 

 Not arguing just havin a laugh,dont be offened✌🏾

[ando76 4,354]

Not offended at all and not interested in arguing.  Just providing clarification. There were 3 screen shots of the 3 intake port flow results from the test head if you recall. One was 'stock port window' one was slightly larger than stock and then there was the 'biggest port window' and biggest port. I've not shown a photo of that port at all. 

The 'cotton wool' port was THOR junior which we did after the 3 test ports and went on the speedway engine. Therefore it had stock port window sizing and a 1.86 valve but still went 240 odd.  The crossflow porting thread has a chronological order of events.  

[slydog 7,873]

Lol come on man that was funny.

[ando76 4,354]

Ok yeah it was funny. The news from Ayr was not so funny tho.  If it's true we are all going to look silly. 

[slydog 7,873]

Been talking to Wazzy and sent him some stuff the other week actually.

[ando76 4,354]

very cool. 

[Valvebouncer 2,389]

Can you guys shed some light on what Wazzy is working on or will it ruin the surprise?

[slydog 7,873]

He has me covered by 50-40hp NA 

[CHESTNUTXE 7,299]

Who is wazzy

[slydog 7,873]

Glenn Wazzmoth from Ayr. And not saying anymore.

[Valvebouncer 2,389]

He has me covered by 50-40hp NA 

Glenn Wazzmoth from Ayr. And not saying anymore.

Sounds like a challenge!

[ando76 4,354]

Who needs a high port crossflow head.

One of our heads, 254@.050 flat tappet, four barrel in a sedan. Untuned and only second time at the track. Told you it would be fast chestnut.




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[CHESTNUTXE 7,299]

it was just for talking point as we need things like that on the forum,was that an auto car ando ? i have that same cam 254 @50