Homemade cherry bomb conversion

[JKY]

I have now completed my cherry bomb conversion having previously discovered that my exhaust box had been completedly emptied of baffle and wadding by a previous owner - this explained why it was resonating so badly to the point of being unbearable.



I decided to install a pair of cherry bombs inside the original box. This was to keep it looking original but also saved me from having to jig the system to keep alignment, and from having to make custom mounting brackets.

The cherry bombs I purchased are technically straight through bullit silencers (cherry bombs are officially the red glasspack bullit silencers from the USA)- mine I think are either Ashley or Sportex. Dimensions are 2'' ID, per the TVR pipes, and the casing is 12'' in total length with 3 1/2 '' main body outside diameter.



I trimmed them to suit and welded them in using small pieces of 2 1/4'' pipe as sleeves. Photos show it all (excuse the poor welding - my mig has not been used for years and the feed was very bad. Also I did not wish to seam weld it all in case I decided to remove it again)











The box was then closed again and the system was re-fitted to the car.
I have only done about 8 miles in it so far but it seems fine and sounds very good. My main worry with doing a straight through mod was that it would be too loud and also they sounds hollow to me. My aim with going the cherry bomb route was to make it a bit louder, but to also absorb some of the high frequency sound. A friend was visiting with his totally standard Griffith 500 so we were able to make direct comparisons - mine is a bit louder but nothing like a straight through conversion. Given a few more miles it should bed in a bit and I will be able to make a better judgement.

Sorry for the rushed post - I am happy to answer any questions.

Edited by JKY on Tuesday 11th November 12:52

Edited by JKY on Thursday 15th October 08:55

[dnb]

Good thread

I'm doing a similar project at the moment, but with the opposite aim. I want my Griff to be much quieter than it currently is, so that I can take it to track days without problem. (Track day silencers won't help because the best I've seen only does -6dB, and I need closer to -20dB to get within spec)

Interestingly, more people complain about the noise my Impreza makes (at 102 dB) than the TVR (at 114 dB). I can only assume that people take more offence at higher frequency noise. It's a shame the standard trackday noise test doesn't take this into account.

[The AJP Griff]

Nice thread indeed,a good job done,there,by the looks of it.Also,making it look so simple to do a nice job like that,has no doubt just de-valued the cherry bomb conversion i was about to put up for sale in the classifieds-cheers!

[Pasco]

The AJP Griff said:

Nice thread indeed,a good job done,there,by the looks of it.Also,making it look so simple to do a nice job like that,has no doubt just de-valued the cherry bomb conversion i was about to put up for sale in the classifieds-cheers!

Ha Ha Ha Ha






You deserved it Ha HA !!

[The AJP Griff]

Pasco said:

The AJP Griff said:

Nice thread indeed,a good job done,there,by the looks of it.Also,making it look so simple to do a nice job like that,has no doubt just de-valued the cherry bomb conversion i was about to put up for sale in the classifieds-cheers!

Ha Ha Ha Ha






You deserved it Ha HA !!

GIT!!

[clive f]

nice job, well done.

mike, sorry cant resist it.............

[dhf]

where did you get the cherry bombs ? any chance of hearing your new exhaust ? thanks in anticipation

[JKY]

I bought them from http://www.motoscope-online.co.uk/exhausts.htm however they arrived direct from Ashley. Price they gave was much better than their listed price.
You could also possibly use a pair of these mini pipes,trimmed to suit, as they are 13'' x 3'' silencers with 2'' outlets - http://www.jonspeed4minis.co.uk/shop/product.asp?p...

Proper USA cherry bombs are available too (ebay etc) at around £40+ each

I can try to get a sound file for you over the next few days. I put a few more miles on it yesterday and it is really settling in well. Sound is just as I had hoped being louder but not OTT. The important thing is that it is very bass in tone without the raspy boom that you get with a straight through. Does not pop and bang on the over run either which is good or bad depending on your preference.
The car is so much nicer to drive now that the resonance has gone (hardly surprising considering it basically had a large empty baked bean can for a silencer before!!)

Edited by JKY on Wednesday 12th November 10:25

[Uncle Fester]

dnb said:

Good thread

I'm doing a similar project at the moment, but with the opposite aim. I want my Griff to be much quieter than it currently is, so that I can take it to track days without problem. (Track day silencers won't help because the best I've seen only does -6dB, and I need closer to -20dB to get within spec)

Interestingly, more people complain about the noise my Impreza makes (at 102 dB) than the TVR (at 114 dB). I can only assume that people take more offence at higher frequency noise. It's a shame the standard trackday noise test doesn't take this into account.

I think there must be quite a few people in this position, I know I am.

My silencer is standard, but the tuning work has pushed the Db level way too high.

There's probably a market for a replacement silencer that seriously reduces volume without spoiling the sound, looks right, and ideally produces more power, certainly not less.

Or failing that, matches the original in such a way that it doesn’t require remapping.

[JKY]

Just an update to this conversion, it has now settled in well and sounds amazing. Pretty loud but not OTT with a very deep base sound. None of the high frequency raspiness that you can get with a straight through conversion. Will try to add a sound file sometime.
Very worthwhile so far.

[Chimjunkie]

JKY said:

Just an update to this conversion, it has now settled in well and sounds amazing. Pretty loud but not OTT with a very deep base sound. None of the high frequency raspiness that you can get with a straight through conversion. Will try to add a sound file sometime.
Very worthwhile so far.

Sound files, yes please. I need to do something like this soon Could be just the excuse i need to play with a mates plasma cutter

[lewton]

[Chimjunkie]

Man of few words is Lewton

[lewis_sharman]

just out of curiosity, how did you weld the bottom of the tubes?

[blitzracing]

I dont think he did, after all it hardly matters as its lagged, and sealed inside another silencer box anyway, so the gas cant escape.

[lewis_sharman]

One last thing, where can you get the lagging from?

(I will be doing this in the near future hopefully)

[clive f]

lewis_sharman said:

One last thing, where can you get the lagging from?

(I will be doing this in the near future hopefully)

available from most spares places, try googling, merlin motorsport, or car builder solutions.

[blitzracing]

Chimjunkie said:

JKY said:

Just an update to this conversion, it has now settled in well and sounds amazing. Pretty loud but not OTT with a very deep base sound. None of the high frequency raspiness that you can get with a straight through conversion. Will try to add a sound file sometime.
Very worthwhile so far.

Sound files, yes please. I need to do something like this soon Could be just the excuse i need to play with a mates plasma cutter

Sound file below, but had to jump of that Zebra crossing pronto however!!

http://www.g33.co.uk/new_page_1.htm

Edited by blitzracing on Monday 23 March 18:42

[LordGrover]

[blitzracing]

Try turning the speakers on ??? Its the only way I could think of to tie a sound file into the forum, or else its just a blank page.