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Extractors for a Holden 308 stroked to 355


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#1 HNSGEQ

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Posted 21 September 2020 - 09:21 AM

Hi All,

I want to build a VN headed 308 stroked to 355 for my LX Torana and like the idea of running 4 into 1 extractors rather than tri-y extractors. Tri-y's seem to be much more popular and wondering whether it's because the 4 into 1's are harder to fit or is there another reason?

 

I would also like to run 1 3/4" primaries and a 3" collector.

 

I'm hoping the engine will make about 500HP and between 420 & 450 ft/lb of torque. 

 

Engine will have approx 11:1 compression, either a solid roller cam or a flat tappet solid cam, Edelbrock Victor manifold, 750 Holley DP and an MSD ignition.

 

Does anyone have anything similar with 4 into 1 extractors or tri-y's to give me their opinion.

 

Thanks in advance guys.

George



#2 Heath

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Posted 21 September 2020 - 01:10 PM

There has always been an issue getting 4-into-1's off the shelf to suit VN-type heads... for as long as I can remember.

But I just had a search and found that CAE are offering "CH-56A" which sound like exactly what you're after. Must be a new-ish product I reckon.

 

https://www.caenterp...y9jaC01NmEuanBn

 

mumbo on here for example was running 10's in a full weight LH/LX with typical small Tri-Y's.

You don't NEED 4-into-1's for the numbers you're talking, I'd guess. But they won't hurt.

 

How do they package? I have no idea.

People have certainly made 1-3/4" custom pipes for VN-type heads in Toranas before that clear everywhere they need to.


Edited by Heath, 21 September 2020 - 01:15 PM.


#3 claysummers

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Posted 21 September 2020 - 02:33 PM

Aren't the four into one a pig on the street? All top end, no low mid torque.

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#4 76lxhatch

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Posted 21 September 2020 - 03:35 PM

^ Popular myth in my opinion.

 

But fitting any sort of 4 into 1s in a Torana can be a hassle (early heads or VN). And going to 1 3/4" primaries makes it harder again.

 

It can be done but either you need to able to DIY or have deep pockets, and there may be packaging compromises.



#5 rexy

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Posted 21 September 2020 - 05:03 PM

There aren’t too many street toranas with 4 into 1 pipes. Having looked at a few over the years they leave a lot less room around things. Not worth the hassle in my opinion.

I run some now very old CAE inch and 3/4 pipes on a COME headed 383 holden that’s been in a couple of LXs. They fit ok. Pretty close in a couple of spots.

 

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#6 gtrboyy

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Posted 21 September 2020 - 05:47 PM

Yep reason why most cars have tri-y design is fitment issues or pay through the nose for custom pipes all in seperate pieces. 1 5/8 tri y work fine for 450-500hp commodores although at that point 1 3/4 more suited...got those in my sle although with 3" collectors & pipes it does seem way overkill for street cars....2.5" colectors is enough. Guessing those 4-1's would be drop front end out to fit or somehow cut flange/pipes to feed them in 2 pipes at a time. bestmufflers.com online shop or just going there usually get good prices & no bs answers..also does custom pipes but for the cost doubt you'd need custom pipes on 10sec street car.


Edited by gtrboyy, 21 September 2020 - 05:53 PM.


#7 mick_in_oz

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Posted 21 September 2020 - 05:56 PM

My Hatch runs Tri-Y 1-5/8" primary, started life as pacemakers, but have been modified with merged collectors, longer primaries and much longer secondaries, 2-1/2" collectors, the guy that did them many years ago (Steve Gay in Mackay) said the had a few sets on 355's making 550HP or there abouts, I spoke with him at length when I put the current engine in 363" with CNC Dash-3's and big solid roller.



#8 mr5000

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Posted 19 November 2020 - 09:19 PM

I’m running a set of custom 4 into ones 1 7/8 11.5 comp flat tappet cam vn heads that have been cnc ported we
Couldn’t run the pipes on the dyno apparently torana pipes are never dyno friendly but it still
Made 520hp with undersized pacemakers and 498 ft


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