The Lotus Grand Tourers

Johnwindwood wrote:Thanks guys-all very useful comments. It's booked in for a tailor made system on Monday. I'll have a chat with them to see how they feel about a centre box delete.

Id be very interested to hear what they have to say about centre box deletion

shaunw wrote:

Johnwindwood wrote:Thanks guys-all very useful comments. It's booked in for a tailor made system on Monday. I'll have a chat with them to see how they feel about a centre box delete.

Id be very interested to hear what they have to say about centre box deletion

I put my centre box back in as it was really annoying for the passenger and added to the motorway drone.

MrCoolA wrote:

shaunw wrote:

Johnwindwood wrote:Thanks guys-all very useful comments. It's booked in for a tailor made system on Monday. I'll have a chat with them to see how they feel about a centre box delete.

Id be very interested to hear what they have to say about centre box deletion

I put my centre box back in as it was really annoying for the passenger and added to the motorway drone.

Mmmmm. Its a difficult one, some say its noisier and some say it isnt Nothings ever straight forward is it.

Good luck John - I'm sure it will work out well.

Regarding sound, beware that an attractive rasp experienced during acceleration can also be an annoying drone at cruising speeds. It all depends what you want of course; if you want to drive the car long distances in some comfort then my advice would be to stick closely to the standard specification, otherwise you enter unfamiliar territory.

Regarding the centre box, if this is a true resonator box and sized correctly it will reduce drone at certain rpm. A good question to ask fabricators is how they calculate the size of this box.

Cheers, Richard

Hi John. Any update on the exhaust?

Hawaiis0 wrote:Hi John. Any update on the exhaust?

Not John but as I had a custom exhaust built without a centre silencer I'll 'pipe up'.

I started with smaller than standard back boxes and no centre silencer. The result was a lot of boom and not much tune. Luckily I had the option to return and have a centre silencer retrofitted. The one fitted is nothing like the original huge centre silencer but has reduced boom ( although not eradicated it completely ) and interestingly introduced a very pleasant sound to the exhaust through first half of the rev range. I'm pretty happy now although I haven't been on a long journey since having the extra silencer installed.. I need to drive the car some more to be sure but the addition of the centre silencer appears to have improved low end torque too, something my car has lacked since I bought it and i suspected was down to lack of back pressure as the baffles on the original exhaust were completely shot.

Shaun

shaunw wrote:

Hawaiis0 wrote:Hi John. Any update on the exhaust?

Not John but as I had a custom exhaust built without a centre silencer I'll 'pipe up'.

I started with smaller than standard back boxes and no centre silencer. The result was a lot of boom and not much tune. Luckily I had the option to return and have a centre silencer retrofitted. The one fitted is nothing like the original huge centre silencer but has reduced boom ( although not eradicated it completely ) and interestingly introduced a very pleasant sound to the exhaust through first half of the rev range. I'm pretty happy now although I haven't been on a long journey since having the extra silencer installed.. I need to drive the car some more to be sure but the addition of the centre silencer appears to have improved low end torque too, something my car has lacked since I bought it and i suspected was down to lack of back pressure as the baffles on the original exhaust were completely shot.

Shaun

Hello Shaun
Talking about low end torque. I can't remember if you fitted the light steel flywheel?

Since fitting mine, with the tuning and 'engine management' settings untouched, mine ticks over much higher (1600 -1800 rpm) when the cold running control advances the ignition below 60 C (full vac advance) but still drops back to normal tick over (950 rpm) when warm with the ignition retarded (no vac adv). I can spin the wheels, plus overall low-down torque is better with less flywheel weight. And this is with the std centre box but the rears are custom jobs which robbed me of some top end power (they are well baffled).

I wondered if you noticed the same after fitting the light flywheel, because I'm quite happy with the low-end torque atm ..it's obviously not a diesel or a turbo, but very driveable non-the-less.

I'm going to need 2 rear boxes , 2 j pipes and one y pipe. At SJs that comes to about £350 less vat. What sort of price is a bespoke build?

Hawaiis0 wrote:I'm going to need 2 rear boxes , 2 j pipes and one y pipe. At SJs that comes to about £350 less vat. What sort of price is a bespoke build?

In my case at least £600 for a SS one 'made on the car'.

Well, I AM John!
Sorry-missed the updates.

Still really pleased with the exhaust. Cost just under £600 made on the car. Centre silencer removed, more efficient rears fitted. Result is slightly more noise overall (But a lovely note!)
No booming and not wearing on a long journey. I'd do it again without hesitation.

While being normally a fan of tubular exhaust manifolds for improving gas flow I wonder for the Excel what happens to temperatures around a tubular manifold and effect on the very close fibreglass body.
Opinions please.

Dave the cog.

DavidOliver wrote:While being normally a fan of tubular exhaust manifolds for improving gas flow I wonder for the Excel what happens to temperatures around a tubular manifold and effect on the very close fibreglass body.
Opinions please.

Dave the cog.

I have a tubular manifold and - for me- heat has not been an issue. The chassis fork sits between the manifold and the body, and seems to provide plenty of protection.

Richard

DavidOliver wrote:While being normally a fan of tubular exhaust manifolds for improving gas flow I wonder for the Excel what happens to temperatures around a tubular manifold and effect on the very close fibreglass body.
Opinions please.

Dave the cog.

The fibreglass on my Elite in that area was virtually destroyed by the heat/oil mist. My Excel was not great in that area either. I think heat shield is really valuable in that area. I shall definitely be fitting some to protect my shiny new paint!!

Pete

Lotus-e-Clan wrote:

shaunw wrote:

Hawaiis0 wrote:Hi John. Any update on the exhaust?

Not John but as I had a custom exhaust built without a centre silencer I'll 'pipe up'.

I started with smaller than standard back boxes and no centre silencer. The result was a lot of boom and not much tune. Luckily I had the option to return and have a centre silencer retrofitted. The one fitted is nothing like the original huge centre silencer but has reduced boom ( although not eradicated it completely ) and interestingly introduced a very pleasant sound to the exhaust through first half of the rev range. I'm pretty happy now although I haven't been on a long journey since having the extra silencer installed.. I need to drive the car some more to be sure but the addition of the centre silencer appears to have improved low end torque too, something my car has lacked since I bought it and i suspected was down to lack of back pressure as the baffles on the original exhaust were completely shot.

Shaun

Hello Shaun
Talking about low end torque. I can't remember if you fitted the light steel flywheel?

Since fitting mine, with the tuning and 'engine management' settings untouched, mine ticks over much higher (1600 -1800 rpm) when the cold running control advances the ignition below 60 C (full vac advance) but still drops back to normal tick over (950 rpm) when warm with the ignition retarded (no vac adv). I can spin the wheels, plus overall low-down torque is better with less flywheel weight. And this is with the std centre box but the rears are custom jobs which robbed me of some top end power (they are well baffled).

I wondered if you noticed the same after fitting the light flywheel, because I'm quite happy with the low-end torque atm ..it's obviously not a diesel or a turbo, but very driveable non-the-less.

Hi Peter. Yes I have the lightened flywheel, I also have L14 cams that the previous owner fitted which I suspect have reduced low end torque to a degree.

To answer your question about the flywheel, I can't say that I noticed much difference in torque at low speed, but ( and I hope it wasn't placebo! ) since fitting the centre silencer I'm sure it pulls.much more smoothly from low rpm. The flywheel and cam combo seem to have most effect at higher rpm as my engine seems faster and more free revving than other standard Excels I've driven

Oh yeah I forgot about the cam change! That will be comparing apples with pears.