Lotus Elan

2 seater / Sprint Exhaust Back box.

PostPost by: Grizzly » Tue Jul 02, 2019 6:23 pm

Hi all.

Does anyone in the Uk have a Sprint exhaust backbox for sale? Ideally in good condition.

Currently i have a Peco period aftermarket back box fitted, frankly it's annoying the neighbors leaving early in the morning and the drone driving it to work gives me a headache before i've even started my day. My original plan was to buy a big bore TTR system but finances are not permitting just at the moment, so i'm thinking of getting hold of a Double s box for the time being but i thought i'd ask here before purchasing.
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PostPost by: Mazzini » Tue Jul 02, 2019 6:54 pm

The TTR big bore fast road system isn't exactly quiet and the routing of the pipes gives a whole new set of problems with heat transference. I tried a thermal coating, but that was no use, I ended up heat wrapping the manifold, but then I had a change of heart and decided to put the car back to standard so I sold the system.
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PostPost by: Grizzly » Tue Jul 02, 2019 7:15 pm

Thats interesting!! it did cross my mind to go for the Kelvedon Mild steel back box which has had allot of good reviews but my thinking was at £500 the TTR system was only another £300ish on top for a full system, that said though it defeats the object if i end up back at square one.

If you don't mind me asking who supplied your stock system? and how do you find it?

The two main thing i find with this Peco box is the idle is loud and it's very raspy (almost unpleasant sounding kind of like the exhaust is blowing but it's not), the annoying thing is i have the round Peco +2 box and that sounds great (i'd love my 2 seater to sound like that).
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PostPost by: patrics » Tue Jul 02, 2019 7:38 pm

Hi
I have the big bore TTR system on my S4 Elan - from my experience it passes noise test so that's good enough, going to any race event should give you a good idea on level.

Regards
Steve
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PostPost by: 1owner69Elan » Tue Jul 02, 2019 8:26 pm

I have the TTR "Race Systems Silencer, S4 and Sprint". I opted for the Race Systems version even though my car is for the street but with over 165hp (the "transition point" specified by TTR). I guess the difference is in bore size, with the race system being the largest.

I found the sound to be quite acceptable. Much less than a previous "glass pack torpedo". At idle, really very quiet. Also, at full song not obtrusive, at least to my ear. In fact, it almost seems too sedate for my "hot rod". But, certainly more socially acceptable.

Only complaint I have is ground clearance as the silencer(muffler) can scrape in some situations. My car is a bit lower than stock, so that adds to the problem.

I have been toying with trying a lightweight racing unit from Coast Fabrications (now Pro Fabrications, also resold by Burns) as they have a unit that is an inch smaller in height (diameter) that would give more clearance. I suspect this smaller muffler will be significantly louder however. (Leno's "26R" uses the Coast Fab muffler).
'69 Elan S4 SE
Street 181 BHP
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PostPost by: Mazzini » Tue Jul 02, 2019 9:28 pm

Grizzly wrote:Thats interesting!! it did cross my mind to go for the Kelvedon Mild steel back box which has had allot of good reviews but my thinking was at £500 the TTR system was only another £300ish on top for a full system, that said though it defeats the object if i end up back at square one.

If you don't mind me asking who supplied your stock system? and how do you find it?

The two main thing i find with this Peco box is the idle is loud and it's very raspy (almost unpleasant sounding kind of like the exhaust is blowing but it's not), the annoying thing is i have the round Peco +2 box and that sounds great (i'd love my 2 seater to sound like that).


The TTR system was fitted to my S2. I kept the original cast iron manifold and I have an original NOS silencer that I'll fit. I'm currently working on trying to import one of Famous Franks oval centre pipes, so hopefully my S2 will sound just like it did in 1965.

My Sprint has what looks like to be a mild steel manifold and a stainless silencer, it sounds awful, like the exhaust is blowing.

The best sounding system that I've had is a PMS stainless manifold with a stainless silencer. That's currently on my S3, but I'm having an originality attack and I may put the original S/E manifold back on the car, then I can put the PMS system onto the Sprint and play with silencers. I too would like a Kelvedon mild steel silencer, but it's painfully expensive.
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PostPost by: MarkDa » Wed Jul 03, 2019 10:22 pm

NOS sprint back boxes do occasionally turn up for sale - I'm still on my original as the car was off road for 30 years whilst I 'matured'
There's no doubt it has the balance if quiet at tickover and strident under power without boom or drone when cruising.
One reads that standard modern stainless systems frpm the usual suspects are ok volumewise but dont have the same tenor.

Is this too loud?

http://redirect.viglink.com/?format=go& ... SAyV9Bgn1g
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PostPost by: Grizzly » Thu Jul 04, 2019 9:17 pm

Mark, To be quite honest it's difficult to tell from the video as to how loud yours is, at face value i'd say mine is similar in full throttle volume if maybe more bass to the note, i'd say ours is quite a lot louder at idle and low rpm though.

The thing with our Mild steel Peco exhaust is it has little to no back pressure, too the degree at 1000rpm the exhaust pulses as each cylinder cycles. Ironically i don't have a problem with full throttle (it actually sounds ok) but idle,low rpm and cruising where it spends most of it's time sounds like it's got a bad exhaust leak (but it hasn't).

Right now i would trade the full throttle noise for a better Idle,low rpm and Cruise. Right now i've nearly talked myself into getting a Kelvedon Mild steel box, it would be a much easier decision if it wasn't 3 times a Stainless box.
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PostPost by: MarkDa » Thu Jul 04, 2019 9:55 pm

As you say noise is relative and subjective.
I think the main point about my video is that the car is still clearly audible long after it is out of sight!
It is nice and quiet at tickover and up close you can hear each pulse.
It's not a straight through box - there's a pipe up one side and another up the other.
When my inlet connection broke off I released the chrome outlet and welded it onto the the other end and reversed the flow.
I think a lot of the exhaust note is due to the manifold and inter pipe rather than just the silencer.
People seem to like the Kelvedon box so it's probably worth the expense if you like the original sound - particularly the mid range cruise.
There's nothing worse than booming and droning - we should enjoy our cars!
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PostPost by: Grizzly » Thu Jul 04, 2019 10:38 pm

MarkDa wrote:I think the main point about my video is that the car is still clearly audible long after it is out of sight!

The difference being you would hear ours at a similar distance cruising at 3000 rpm.
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PostPost by: Grizzly » Fri Jul 05, 2019 4:20 pm

Not sure if this is Stainless or Mild steel back box but would you agree it's what an Elan should sound like? bear in mind he's not got the air filter can or trunking fitted so maybe more intake noise (skip to 6.55) https://www.youtube.com/watch?v=W3KWU1qlfIM&t=466s

Does look like a Mild steel manifold so might be OEM.
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PostPost by: MarkDa » Fri Jul 05, 2019 4:46 pm

The box doesn't look rusty enough to be mild steel and its welded bracket is the wrong shape for an original.
So I'd say it's stainless - but it does sound ok.
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