Big bore exhaust.

[dougal9887]

Hi all,
Has anyone fitted the TTR big bore exhaust in a Plus 2? If so can you describe alterations required to the chassis cut-out please. Any other issues? Thanks.
Dougal.

[rgh0]

I have not fitted the TTR headers and Exhaust to a Plus 2 but have to my Elan and I think understand the issues in fitting to a Plus 2.

The issue requiring work for clearance in the Elan is the chassis top flange behind the engine mount. The Plus 2 chassis is identical in this area and will need the same style cut-out. There are plenty of photos of what people have done in this area on the forums. Personally I made a oval recess in the top flange about 2cm deep and10 cm long to provide the clearance needed. I formed this by panel beating the top flange into the required shape with a hammer and dolly rather than by cutting and welding as many have done.

The fibreglass of the firewall and passenger foot well ( in a RHD car) in an Elan is close to the headers and needs some heat insulation as is common with other headers. The body work in the Plus 2 has greater clearance in this area but will also probably benefit from some insulation.

If you have a 5 speed Plus 2, clearance with the bigger and squarer bottom of the 5 speed box may be an issue with clearance in this area but it should be correctable with a little additional bending of the pipe in this area if required.

cheers
Rohan

[dougal9887]

Thanks for the reply Rohan.

I like the idea of panel beating the flange as opposed to the cut and weld method. Would you say that your 2cm x 10cm indent was centered on the existing notch?

I hadn't thought of the potential problem of clearance for the five speed box, perhaps that's something that TTR can advise on.

I've got plenty of left over ceramic needle mat from making up a new silencer heat protector shield and imagine that a similar construction on the passanger footwell would be effective.

Dougal.

[Tahoe]

Will this same modification be required on a Spyder chassis?

[rgh0]

Will this same modification be required on a Spyder chassis?

The clearance with the top chassis rail in the space frame Spyder chassis is greater and they should fit without any needed chassis mods I believe.

Rohan

[Uboat]

Hi Dougal,
I recently fitted a big bore TTR exhaust, all parts, in my +2. I agree with Rohan's input regarding the
modification of chassis and the bulky a five-speed. Also:
- Silencer and central exhaust pipe is a nice fit
- A noticable boost of HP
- Say goodbye to the decent original soundtrack. Exhaust note will be LOUD. Perfect on the track and for enthusiastic driving, less perfect for long-distance touring,
/Ulf

[dougal9887]

Hi Ulf
Is your car 5 speed and did you have problems getting past the box?

Dougal.

[Uboat]

Yes Dougal,
it is a 5-speed car, and it was not a straight fit around the gearbox. Some heating on the pipes and a little bending was needed for clearance of gearbox. The heating of the manifold is not an issue on my car (although it would be easy to fit a heat shield or insulation).
/Ulf

[dougal9887]

Hi Ulf,
Which pipes require bent and how do you go about bending? Do you need to hire a tube bender or something?
Thanks,
Dougal.

[Uboat]

It was the secondary pipes that connects to the y-piece that were bent. They were first heated by a torch then bent carefully,
/Ulf

[dougal9887]

TTR big bore exhaust system arrived today. The complications of getting around the 5 speed box had been weighing on my mind for weeks so I was keen to get it mounted and have a look at the problem. The secondary pipes are 1 5/8" od and the main pipe is 2". When held in position, the 2" end of the Y piece was going to foul the gearbox by about 1/2 it's diameter, 1", but it didn't look as if too much bending of the secondaries would be required to achieve this. So I set to!
1st up was to find a length of stout tube for use as a lever that was a tight fit in the secondary pipe so that it wouldn't deform. Best I could find was an axle stand tube. It was a bit short but, with the stand reversed on it, looked ok. A little grinding gave a perfect fit. I used an ordinary blow torch with a MAPP gas bottle and supported the manifold against a scrap of plate steel.

Bending the secondary pipes.

I could feel the pipe bending with heat and pressure and test fitted it a couple of times to avoid going to far.

TTR big bore exhaust. 5 speed gearbox.

.2" clearance.

Overall view.

Final fit looks pretty good. I've got a .2" gap between the exhaust and gearbox.
Is that enough?
Dougal.

[rgh0]

The 0.2 inch gap should be fine as they both move together with the engine

cheers
Rohan

[Foxie]

I have the TT exhaust on my Spyder chassied +2. No chassis modifications required, but even with the exhaust studs cut back to minimum and using 10mm flanged nuts, removing/refitting the exhaust with the engine in situ is a bit of a fiddle, requiring the engine mounts to be disconnected. So my preferred method is to remove the engine and gearbox as a unit, with the exhaust still in place.

A little lowering modification was required to the main pipe to clear the Voigts T9 gearbox, which leaves the main pipe a bit low and liable to grounding, so it is skidded.

[Famous Frank]

Dougal,

It's all looking very good. Thank you for the great pics. They truly are worth a thousand words!

Frank

[dougal9887]

Just to complete the thread, here is the fitting of the centre pipe and silencer once the engine went in.
Having bent the manifold secondary pipes to clear the five speed box, the centre pipe was at the wrong angle. I corrected this by cutting at the bend and holding the two pieces together with a jubilee clip so that I was able to swivel the main length of the centre pipe until it lined up.

Centre pipe cut and held with jubilee clip.

The cut could then be welded up to give the correct angle.

Centre pipe bend at new angle ready to weld.

Completed system.

The exhaust note is great but it is loud, so I'm now thinking of adding an additional silencer in the center pipe. Burton do one that is about 4" diameter x 18" long which should just clear the chassis closing plate. It will also reduce road clearance by 1", but should still be ok.
Has anyone tried an intermediate silencer?
Dougal.