Author Topic: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget  (Read 1674 times)

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Offline Mecky

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Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« on: Wednesday,July 10, 2024, 03:20:39 AM »
Hi guys,

as you may have read in other threads of this forum, I'm racing a Europa S2 with 807 Renault engine. After several very disappointing years (2021 - 2023), I chose to do some major (at least in relation to my budget) investments into the performance and relaibility of the car. A whole new engine from a Renault Alpine expert and a new shorter differential are the two most significant upgrades, which occupied a huge chunk of my racing budgets from 2023 and 2024. But still, there is that 25 years old exhaust in my car, which was selfmade by a previous owner. I want to get rid of it ASAP, because it's ugly and heavy. If the replacement exhaust delivers a couple more horsepower, that would be a bonus on top. The only problem is the budget. I have no budget left for a custom-built exhaust. That's why I'm trying to find a way, which means a lot bang for buck: The x-flow header from Lotus Supplies aka. Banks Engineering (https://www.lotus-supplies.com/parts/exhaust/renault/exhaust-header-hand-formed-renault-x-flow-s2/).

I would like to share some thoughts about that Banks exhaust manifold: I purchased it, because it's cheap and looks like a good design for gas flow, especially in relation to the costs. But as my racing racing engine with 1597 cc has big valves and revs up to 7300 RPM, my feeling is that the step from four Ø42 mm tubes into one Ø48 mm tube is too small. From research in books and magazines, I found that such a step would even be considered small in a 2-1 collector, not to mention 4-1.
In addition, my exhaust ports are diamond-shaped and that form does not match the exhaust flange. I tried to grind them bigger, but there is not enough material on the original flange. Thus, I have to change the flange in order to use the Banks manifold. And while I'm already at it, I will also increase the diameter of the collector tube to 52 mm, so that I can fit a 55 mm muffler to it.

My new enigne didn't do a maximum power run on the dyno so far, but I would like to do one soon. The only dyno-run so far was right after the engine was built, two hours after start-up during the break-in phase. There it was shortly reved up to 6000 RPM and delivered 140 HP and 163 Nm. My target is something around 160 HP at ~7000 RPM and from the diagram, this should be possible.

Valerio Leone (former member of this community) used the Banks manifold in his race car, but he sold the car and deleted his socials lately. Funnily, I'm going to meet the new owner of his car today. It was sold from Italy to Germany, very near to my place. I'm going to have a chat with the new owner. Maybe he even has a dyno sheet of the car in its current configuration.

What do you think of my thoughts and how are your own experiences of this exhaust manifold? Does anybody use it for racing or had it dyno-tested?
I'm looking forward to your feedback.

Offline TurboFource

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #1 on: Wednesday,July 10, 2024, 03:33:17 AM »
Can you add an adapter plate between the head and header that transitions from one shape to the other?
The more I do the more I find I need to do....remember your ABC’s …anything but chinesium!

Offline BDA

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #2 on: Wednesday,July 10, 2024, 08:02:30 AM »
As far as the exhaust is concerned, I agree with all your points. The new headers look A LOT better but the collector and tail pipe do look a bit small. I might be a bit concerned about the water pump so close to the headers but it was close before so maybe it really isn't a worry... I'd probably wrap it with some insulation just to make double dog sure it's ok.

Offline TurboFource

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The more I do the more I find I need to do....remember your ABC’s …anything but chinesium!

Offline Kendo

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #4 on: Wednesday,July 10, 2024, 12:55:58 PM »
Did you mean 160 HP at 7000 RPM?

Offline Mecky

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #5 on: Thursday,July 11, 2024, 12:31:37 AM »
Hi guys,

thanks for your replies.
Can you add an adapter plate between the head and header that transitions from one shape to the other?
That would be possible, I guess, but it exceeds my abilities and capacity in the moment. That's why I'm going with the new laser-cut flange from the template of my exhaust gasket with diamond-shaped ports.

As far as the exhaust is concerned, I agree with all your points. The new headers look A LOT better but the collector and tail pipe do look a bit small. I might be a bit concerned about the water pump so close to the headers but it was close before so maybe it really isn't a worry... I'd probably wrap it with some insulation just to make double dog sure it's ok.
You are right. The water pump next to the exhaust is not ideal, but I never had trouble with that before and the water temperature was very easy to control, thus I have ne worries. If in doubt, I will wrap the exhaust with heat deflection tape.

https://www.motortrend.com/how-to/proper-exhaust-header-collector-volume-vs-engine-size/
Thank you for that link. It's mostly about the lengths, but they are not something that I'm able to change in the moment. I'm afraid, I have to stick with the bent tubes from Banks.

Did you mean 160 HP at 7000 RPM?
Of course, you are right. I corrected it in the original post.

I visited the new owner of Valerio Leones Europa S2 Hemi 807 race car yesterday. The owner is still fighting for the FIA Historic Technical Passport, as Valerio was already since 2014. Never ending story and I'm afraid, it will most likely not be crowned by succes. But the car itself is in great condition. It was dynoed with 160 HP and 176 Nm of torque with the original Banks header. Thus, it can't be bad. But as for the header flange, I have to change that anyway. That's why I already cut the Ø48 mm tube after the collector and replaced it with a Ø52 mm. The laser-cut flange is ready and I will pick it up tomorrow. I hope that the complete new exhaust system will be ready in a week time. Not sure, If I'm able to go on the dyno before the next race, but I definitely want to compare new and old exhaust on a dyno in July or August.

Here are some pics of the exhaust of Valerio's old car:

Offline Mecky

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #6 on: Thursday,July 11, 2024, 11:44:10 PM »
Eventhough, I'm now calmed by the fact that the exhaust is good enough for around 160 HP, I still have to change the flange in order to make it match my cylinder head exhaust ports. The new flange arrived today and I already like the way it looks.

In the detailed photo of the port, you can see the real issue: The inlet of the manifold are ground bigger, which seems to be enough-ish. But since then, there is not enough material left to make a gasket work. The stock gasket is too small and the Alpine racing gasket shape has ports so big that they are even bigger than the stock flange in width. The new flange was made using the Alpine racing gasket as a template, by the way.

Offline TurboFource

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #7 on: Friday,July 12, 2024, 03:28:23 AM »
I would add weld material to the original flange to create more gasket surface.
« Last Edit: Saturday,July 13, 2024, 03:44:21 AM by TurboFource »
The more I do the more I find I need to do....remember your ABC’s …anything but chinesium!

Offline Mecky

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #8 on: Friday,July 12, 2024, 10:04:48 PM »
I thought about that, but the problem is that I don't have a mill to make it a plain surface for the gasket after adding material at several places. That's why I went for a whole new flange.

Offline kram350kram

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #9 on: Saturday,July 13, 2024, 08:21:24 AM »
Can you not use the new head flange as an adapter, welded to the new header, then port all that for a smooth entry? Weld from the inside and avoid the mating surface. This would move the header away from the head so you may not have the room and bolting on might be an issue?  I did notice the original header pipe opening was too small with the reversion marks. What is your header pipe size and what is the area of the head port opening? The new header might be too small for the head ports and exhaust valves in any event. So, as you are aware a smooth exhaust entry transition is paramount, even having a larger header opening is helpful as an anti reversion step.

Offline Mecky

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Re: Banks Renault X-Flow Header or Building a Racing Exhaust on a Budget
« Reply #10 on: Tuesday,July 23, 2024, 12:54:42 AM »
An adapter would be possible, but it would change the overall fit of the exhaust in the engine bay. I'm not saying that it's impossible, though.

I noticed after spot-welding the flange to the tubes for the first time that a small change in direction or angle has quite big consiquences for the fit of the exhaust in relation to all the other components. But at the end, I managed to put the exhaust in with the new flange. I quite like the results from an optical point of view. It definitely works. I tried it already on the race track. But dyno comparison with the old exhaust is still pending.