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Discussion Starter #1
Had another look at the original design and made a few improvements.






This is an all-Stainless header. I've paid attention to clearances around the trunk area and there's maximum clearance at driveshaft and alternator. It weighs 10lbs. Supplied with my own large-port gasket header gasket and fitting kit to the Cat/De-Cat.

With the N/A 2zz-ge somewhat lacking in torque, you need a 4-2-1 layout. Combine this with the stepped primary to keep the gas-speed up at lower revs and there's a very good improvement in torque all round - at least 12ft/lbs.
This is a high-rpm motor, so no long-runner design would work properly. You'll notice I don't use the same header for the 2zz-ge SC installs - that is a totally different motor, requiring a totally different 4-1 header!
I eased the bend angles to improve flow and increased the diameter of the primary collectors to cope with that - works very well - at least 15bhp.
The secondaries are a larger diameter than what I've seen on other offerings - they need to be - this motor revs and with the increased lift of the VVTL-i - there's a serious amount of air being flowed.
Finally, this is a fully sealed header - no slip-joins/springs - the 1st Lambda which controls the fuelling, would be all confused with the constantly changing AFR's caused by those sliding joins.

Price: £595 - approx $950. (+20%vat for EU purchases).
 

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Discussion Starter #2
Hoo! Tough crowd - over 120 views and no comments? :confused:
 

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I suspect people are probably a bit off-put by the price/performance ratio for the N/A car (I could be wrong.) Not that you have priced it incorrectly, but in the grand scheme of things, it seems like this is a *relatively* expensive upgrade (says the guy who spent three times as much on his exhaust.) However, your reputation speaks for itself - no one could possibly go wrong with one of your exhausts.

That said, I love that you have a passion for this stuff and keep squeezing the last lb-oz of power out of the motor. How much weight does this save over the stock headers?
 

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I suspect people are probably a bit off-put by the price/performance ratio for the N/A car (I could be wrong.) Not that you have priced it incorrectly, but in the grand scheme of things, it seems like this is a *relatively* expensive upgrade (says the guy who spent three times as much on his exhaust.) However, your reputation speaks for itself - no one could possibly go wrong with one of your exhausts.

That said, I love that you have a passion for this stuff and keep squeezing the last lb-oz of power out of the motor. How much weight does this save over the stock headers?
It is priced right.
I bought a PPE header for 895 from BWR.
 

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I may be in the market for this once I get back to FL...looks nice.

Are those gains at peak, or just at certain points in the powerband?
 

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Wow very nice, I would have gone with this one had it been available. I like the long sweeps. Does it work with all exhausts, including the Stage II? I know other manufacturer's headers do not work with the Stage II.

Any high flow CATs in the work for a total system?
 

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Discussion Starter #10
Thank you guys! I was a bit puzzled by the lack of responses since I've had a lot of enquiries about the 4-2-1 recently.
Mike, I'll reply to your e-mail today - Sunday is e-mail day!
You DO need a tune with the header. I wonder if Koldfire could do this - seems to be the one these days.
I knew it would be easy to bolt on a header which gave more power, the stock design is kinda weedy BUT I didn't want to lose a single ft/lb of torque! That's easy to do just using a bigger bore. So, it had to be a 4-2-1 - with a step.
A lot of manufacturers don't understand the step. It can only be a certain length - you're just keeping the gas-speed up as it leaves the cyl head, no more. That gives good exhaust scavenging of the waste gases AND helps pull in the new inlet charge. Too long a step and you're restricting power higher up the rev range.
The improvements are from 3000rpm on. There's no-where on the dyno curve that it drops below stock. I think Mike is going to run it - be interesting to see how it does with US fuel and another map.
 

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The car forums in general here in America have really slow down over the last couple years. Even most of the car modification magazines have closed doors. The government keeps saying the economy is "recovering", but it seems people still don't have money to do the hobbies.

As I have said in the past, the price from 2Bulars perspective is great. The problem is the conversion to dollars. But thats not something he can help. Its also why Lotus is a fantastic deal at $35,000 in UK and questionable at $60,000 in America.

Still satisified with my 2bular V-Bands.
 

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Discussion Starter #12
The car forums in general here in America have really slow down over the last couple years. Even most of the car modification magazines have closed doors. The government keeps saying the economy is "recovering", but it seems people still don't have money to do the hobbies.

As I have said in the past, the price from 2Bulars perspective is great. The problem is the conversion to dollars. But thats not something he can help. Its also why Lotus is a fantastic deal at $35,000 in UK and questionable at $60,000 in America.

Still satisified with my 2bular V-Bands.
Thank you David :wave:

You really started something with those V-Band pics!
 

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Discussion Starter #14
You have
Me confused on clearance for driveshafts. This is for Elise right? A car that has no driveshaft.
Tomato/Tomaaahto - 2 nations separated by a common language ;)

Propshaft/Driveshaft. Driveshaft/Axle shaft.
 

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I think there has been a small revival amoung the group which wants to get NA power, the timing may be right on this product. Admittedly, most people who purchase header-back exhausts end up commenting more on the sound than the power. Sound can be important (it has kept Harley in the marketplace, even though their designs are antiquated). It gets tough to get much more NA power out of an engine which leaves the factory at 1.73HP per cubic inch, by simply adding bolt-on components. By comparision, the 7 liter 505HP Z06 (2012) corvette only achieves 1.2 HP per cubic inch from the factory. Like most people, I like it when additional innovations in Lotus power goodies continue to appear on the market.
 

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Discussion Starter #16
Wow very nice, I would have gone with this one had it been available. I like the long sweeps. Does it work with all exhausts, including the Stage II? I know other manufacturer's headers do not work with the Stage II.

Any high flow CATs in the work for a total system?
Ah, I'll try that combo in the jig tomorrow. The Stg2 collector/tips being pushed up inside the exhaust bay can be tricky with clearances.

200cell Sports Cat to go with the header:



I make the largest diameter Sports/Race Cats on the market - 125mm dia (5").

With the 3-bolt flange, you have a strong/sealed unit and the all-Stainless flexy section allows for excess engine/trans movement - bad on these cars.

Price: 200cell Sports Cat - £332. (+20%vat for EU purchases) - approx $530

100cell FIA Approved Race Cat - £414 (+vat). - approx $660.

De-Cat/Flexy for the track fiends:



Price: £105 (+vat). - approx $168.
 

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Sorry, didn't think of that.

Here in the states if it drives a wheel it's an axleshaft. If it drives a differential or T Case, it's a driveshaft.

Tomato/Tomaaahto - 2 nations separated by a common language ;)

Propshaft/Driveshaft. Driveshaft/Axle shaft.
 

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Hoo! Tough crowd - over 120 views and no comments? :confused:
2b: I feel like a bit of a shyte making first post that will be somewhat critical - or at least quizical, but meant with the best of intention. Many years ago, I used to build a lot of exhaust systems for VW air cooled and water cooled engines. The state of the art (science?) at that time was to use the shortest possible primaries and calculate the secondaries to provide the resonant length to tune out to desired RPM. IIRC, using A/R flanges did NOT make any difference to that strategy (that was new idea then, the primary tube intersection provided as much of the anti-reversion as constant diameter flanges, ports and primaries could get to that time). Most of our inline engines used 20 - 30" secondaries - 20" being either for VERY high RPM or compromised from space, not ideal at all.

Mind if I ask why the uber long primaries and short secondaries?
 

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Discussion Starter #20
2b: I feel like a bit of a shyte making first post that will be somewhat critical - or at least quizical, but meant with the best of intention. Many years ago, I used to build a lot of exhaust systems for VW air cooled and water cooled engines. The state of the art (science?) at that time was to use the shortest possible primaries and calculate the secondaries to provide the resonant length to tune out to desired RPM. IIRC, using A/R flanges did NOT make any difference to that strategy (that was new idea then, the primary tube intersection provided as much of the anti-reversion as constant diameter flanges, ports and primaries could get to that time). Most of our inline engines used 20 - 30" secondaries - 20" being either for VERY high RPM or compromised from space, not ideal at all.

Mind if I ask why the uber long primaries and short secondaries?
How dare you! :D

Looking at the 2zz-ge stock header:
It's a 4-2-1 design, short/small-bore primaries (1.5"dia)and the longer secondaries formed by a pressing with a splitter plate down the middle (bifurcated to use the Lotus parlance). They needed a 4-2-1 design because Yamaha designed a typical Jap bike motor; comparatively high bhp, not a lot of torque! Mr Honda said "Why do I need torque when I have revs?" Fair enough for the racer I guess.
Manufacturers like small-bore = small radius bends - nice, compact packaging easily covered by the heat-shield. Longer secondaries can find more room further down the engine bay. Interestingly, the 1zz-fe isn't so short of torque and Lotus don't use the spitter-plate in the secondary section. So it's a short 4-1 - an easy header to improve upon:





Looking at the 2bular 2zz-ge 4-2-1;

It's actually a short header, compared to some I've seen. A modern twin-cam/16-valve doesn't need lonnnnnng primaries - doesn't need long anything!
I wanted more power (who doesn't?) but I didn't want to lose ANY torque. So you need to keep the gas-speed high, create a scavenging effect at the exhaust port.
Look at any 4-2-1 dyno curve and you see the characteristic curve with the two dips. This is the harmonics (3rd/5th etc) chiming in. It's good if you can smooth them out and I tend to use a staggered-length secondary section to help with that. You say "uber long primaries and short secondaries" but that's not the case. The secondary length begins at the start of the primary merge and ends at the start of the secondary merge - they're long enough to do their job.
 
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