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PostPosted: Sat Mar 02, 2013 5:38 pm 
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Well I went to the OC rolling road day at Interpro today - car made 411bhp and 375lb/ft which I was well pleased with on a little hybrid turbo. However I got them to do another run with the exhaust bung in that is used at Castle Combe and unbelievebly lost 100lb/ft of torque! No wonder the car didn't feel as quick as normal on the day, it was loosing over a quarter of its power due to the bloody bung!

Needless to say I've got the car booked in to have another box put into the exhaust so I never have to use the bung again!

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Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now! :D


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PostPosted: Sat Mar 02, 2013 5:55 pm 
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Great result Edd.

That's a very dramatic demonstration of exhaust restrictiveness affecting power!

What exhaust are you using out of interest?

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PostPosted: Sat Mar 02, 2013 6:43 pm 
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Hi Mike, its a Japspec 3" system with 3" decat and tubular manifold. I was getting 102db with it at Combe so I think pretty much any extra box would drop this down well within the 100db limit - the bung was dropping it to 88db!

The technician at Interpro told me never to use the bung again as it was risking cooking the exhaust valves.

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GT4 no 10 - I must be mad :help:
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^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now! :D


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PostPosted: Sat Mar 02, 2013 11:06 pm 
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Treacle wrote:
The technician at Interpro told me never to use the bung again as it was risking cooking the exhaust valves.
I wonder if the effect of the bung is increased exhaust back-pressure and poor scavenging of the cylinder. This might cause overheated exhaust valves and burning of the valve seats?

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
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PostPosted: Sat Mar 02, 2013 11:24 pm 
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would definatly make sense don, if the bung restricts gas flow, its going to be hanging around in the primaries of the maifold/cylinder for longer and I know on an NA setup at least, the was the exhaust gas from the previous cycle helps to evacuate the next exhaust stroke. Looking at the dyno graph, was most of the power lost at the top end or was it throughout the whole rev range?

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PostPosted: Sat Mar 02, 2013 11:54 pm 
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It was lost throughout the rev range but the gap between the two graphs got bigger as the revs went up. Without the bung in when the car hit full boost the graph was going almost vertical up to max power and then flattening out, with the bung it was much less steep and took probably 1000 more RPM to get to its peak.

Unfortunately they didn't give me a print out of the graph with the bung in, only the normal one.

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GT4 no 10 - I must be mad :help:
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^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now! :D


Last edited by Treacle on Sun Mar 03, 2013 1:09 am, edited 1 time in total.

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PostPosted: Sun Mar 03, 2013 1:02 am 
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Interesting - sounds like one more exhaust box should do the trick though :)

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PostPosted: Sun Mar 03, 2013 9:06 pm 
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If its the front undertray you want from me, then inmite be able to do an offer.
Also regarding the rear diffuser, youll find the supra one will fit better than the RX7.


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PostPosted: Sun Mar 03, 2013 10:49 pm 
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Yeah I would definitely be interested in a front splitter (and maybe some other bits) if you could do something on price, I will message you.

Also I know you guys sell fibreglass front wings, do you make or would you consider making some 20-25mm wider ones in the stock shape? I think these would be really popular as it would allow people to run a bigger choices of wheels and match any rear track increases with similar ones on the front. I would certainly snap up a pair if you made them.

Yeah I had thought the supra diffuser might be a better choice as its flat across the leading edge whereas the rx7 ones have a raised channel all the way to the front meaning the side bits wouldn't sit flat against the fuel tank.

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^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now! :D


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PostPosted: Sun Mar 03, 2013 11:24 pm 
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I would be willing to do you a deal for something in return.
Regarding tye front wings, Im afraid we cant make indipendant wide ones because the mould is pretty much set. However being that they are made of fibreglass, it does mean its esay to cut and diy mod unlike metal.
If you want it to match the rears the difference between off sets is 20mm.


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PostPosted: Tue Mar 05, 2013 9:14 am 
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hi Edd dident know you were on here lol you going to look at fitting a second box in the exhaust like i have to get the DB down? as i was telling you i got mine down from 106db to 86db and now power lose :)

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PostPosted: Tue Mar 05, 2013 11:18 am 
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Yes I am everywhere, omnipotent and omniscient ;)

Yeah the car is going in to Longlife exhausts (Interpro) soon to have another box put in. I'm hoping that just replacing the tiny centre box with a bigger one would be enough to solve the problem - you can see it here on my exhaust before it was fitted, just before the it goes up over the rear axle with a hanger on it, its only about an inch bigger than the main pipework.

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GT4 no 10 - I must be mad :help:
Image
^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now! :D


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PostPosted: Tue Mar 05, 2013 11:31 am 
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We had a mobile valetter in the work carpark yesterday so I got him to spend a couple of hours doing some paint restoration on mine to remove fine scratches etc - pretty chuffed for £20 spent, came out really well:

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GT4 no 10 - I must be mad :help:
Image
^^^Click the banner for my Black Treacle project thread ^^^

Now back home and mapped to 531bhp & 411lb/ft - that's enough power for now! :D


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PostPosted: Tue Mar 05, 2013 11:40 am 
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looking good mate

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PostPosted: Tue Mar 05, 2013 4:48 pm 
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Looks really smart Edd.

Looking to get the same done once my car is mechanically sorted. Before I spend more pennies on a respray. :)

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