Performance U20 Header Discussion

[mtresillian]

Best and only 1 5/8" header?
Big call
So if we are in the habit of making calls, these 1 5/8" long headers crap all over the short headers of the above design. Proven repeatedly on a reliable engine dyno. Rebello should know better than to utilise such an inefficient design.

Plus with the Aussie design pipes, All the manifold buts are easily accessed with the solex carbs attached.
M

[theunz]

That is indeed a nice looking header, but is it commercially available, and at what cost?

[spl310]

Unless I am mistaken, that is a Lot Mondello header. Yes, available, along with other options. No idea on price.

[david premo]

That is one sweet looking equal length header, good job Lou! I’ve had an 1&5/8’s stainless header on my car I bought from Stan Chernoff about 14 years ago, and it’s very nice, but Lou’s header is for sure going kick butt on the performance.

[theunz]

I thought that might be a Mondello header. IIRC someone posted a while back a price of about $2,000. A true example of the law of diminishing returns!

[Tomc18]

And then there are the next gen tuned length headers ... if you don't have a budget

Engine with pipes.jpg

And alloy sump with alloy insert

Sump with alloy insert.jpg

[notoptoy]

This thread has been separated from a vendor post on a reproduction part.

[Pjackb]

I thought that might be a Mondello header. IIRC someone posted a while back a price of about $2,000. A true example of the law of diminishing returns!

Yup only for someone who wants all the HP they can get
That's $2000 AUS so not that bad , Actually its more around $2500 I heard last
For the other header TomC posted you're looking at double that

[2mAn]

That header is amazing, but I have to agree that its for those squeezing out every last BHP out of the motor.

Im pretty sure Will took a few headers out to TEM Machine who has both my head and his head there. He has been flowing them to get a good idea of the headers' value on the different sizes

[SLOroadster]

That header is amazing, but I have to agree that its for those squeezing out every last BHP out of the motor.

Im pretty sure Will took a few headers out to TEM Machine who has both my head and his head there. He has been flowing them to get a good idea of the headers' value on the different sizes

I haven't heard the outcome of the flow test. I might be able to stop by tomorrow and see how things are going.

Will

[mtresillian]

There are a couple making these headers in Australia now and the price has come down. (Recent small batch advertised at $1200 AUD each) They dont squeeze every last hp out of the engine, they transform it: 20% more at around 3000rpm tapering to 8% at 6500 as per engine dyno. And its not just about flow, it's about the tuned length. The short pipes that have been aroind for so long are just poor design.

PS i have no vested interest in any datsun part/product. But evwn if they were $2k a set they trump any other engine change in $/hp.

[2mAn]

There are a couple making these headers in Australia now and the price has come down. (Recent small batch advertised at $1200 AUD each) They dont squeeze every last hp out of the engine, they transform it: 20% more at around 3000rpm tapering to 8% at 6500 as per engine dyno. And its not just about flow, it's about the tuned length. The short pipes that have been aroind for so long are just poor design.

PS i have no vested interest in any datsun part/product. But evwn if they were $2k a set they trump any other engine change in $/hp.

Can you share who else is making them? Are they just copies of Lou's work?

[CSP311]

And for me, with the larger cc (2000+) they help the engine breathe, no point having a "restrictive" header, a must.

[GoldHawg]

There are a couple making these headers in Australia now and the price has come down. (Recent small batch advertised at $1200 AUD each) They dont squeeze every last hp out of the engine, they transform it: 20% more at around 3000rpm tapering to 8% at 6500 as per engine dyno. And its not just about flow, it's about the tuned length. The short pipes that have been aroind for so long are just poor design.

PS i have no vested interest in any datsun part/product. But evwn if they were $2k a set they trump any other engine change in $/hp.

Is there a difference between tuned length and equal length? In my research on header builds, the consensus is that once you get to about 24" runner length, equal length doesn't get you much performance--runner length and then the throat length of the collector seemed to be king. Given the complexities of the Roadster chassis, I gave up on trying to make them exactly equal length and concentrated on ensuring I could get to 24" runner length with a nice merge collector. Anything more was said to only be beneficial if the header could be matched with a cam--that level of tuning could get more. If Lou's is that much better, does it only apply if you copy the whole recipe, i.e., his cam profile, head porting, etc?

[mtresillian]

I think equal/tuned length are used somewhat colloquially however agree with your differentiation. The focus on our headers was to get length, make them as equal as possible (there are only mm difference in each length and as you mentioned a strong focus on the collector design. The overall length is a bit shorter than ideal due to the chassis cross member but a long way (pun intended) improved compared to the standard available 'performance' headers. They are transformative rather than an improvement over the usual headers. As Lou's dyno figures mention 20% increase at 3000rpm tapering to 8% at 6500. This is on the Heenan and Froude engine dyno he uses.

At present, in Aus, the headers are $1500 AUD (due to them hand made in low volume) but the only consideration would be the steering column and how that might fit with the header pipe. A set have been installed on a LHD car here though: previously Victor Laury's car.

Happy to explore options if anyone is serious about buying a set. I live close to Alastair Sutton-Davies who makes them for our club members. HE does not do it commercially, but has been making them on request for members. Their performance speaks for themselves so he has made quite a few sets now.

So numbers aside what are they like to drive?

The engine idles very smooth. Remember we have all solex/B Cam cars in Aus and they idle a little lumpy with 20deg btdc timing - this is normal when running unequal length headers. The U20 is sensitive to exhaust scavenging and these pipes even up the cylinders.

- First thing you notice is how you can basically let the clutch out at idle and the car drives off. Hill starts are not an issue, don't need clutch slippage anymore.
- Second - throttle response is great at lower RPM (1500-2500) and when you open the throttle esp under 2500, it pulls like a truck.
- Third - they breathe well and if your intake is flowing well (double filter setup on solex) the engine revs effortlessly to 6500 and pulls.
- Fourth - they sound great and you can hear them working - the note changes significantly at various RPM ranges.
- Fifth - I no longer get reversion carbon deposits on my intake ports (this may be a B-cam phenomenon, people smarter than I can correct me)
- Sixth - better fuel efficiency - however I use more because I now drive my car harder cos it's so much fun.



Michael