best way to induction with a single carb?
05 January 2006, 12:20 PM
#1
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best way to induction with a single carb?
Im supercharging my GT6 in the near future and was wondering what was the best way out of the ideas below is best. I can cut a manifold and weld on an airbox or bolt one on to the current manifold where the 2 carbs go. any ideas? thanks
05 January 2006, 12:51 PM
#2
Generally speaking 1 or 2 as throttling down the rampipes into two main inlets can cause turbulence. Better have one plenum equally shared by equal length and spaced ram pipes for each cylinder.
Although, it shouldn't really matter if the plenem chamber is always under positive pressure.
If the supercharger is underrated or undergeared too much, it may cause a vacuum at high revs, which would make the design more critical. But in reality never happens beacuse you would have done the homework to makesure the right supercharger and gearing is used
Although, it shouldn't really matter if the plenem chamber is always under positive pressure.
If the supercharger is underrated or undergeared too much, it may cause a vacuum at high revs, which would make the design more critical. But in reality never happens beacuse you would have done the homework to makesure the right supercharger and gearing is used
05 January 2006, 02:15 PM
#3
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so, now, which is better of 1 or 2. i think locating the pipe from the other side of the engine will be easier on number 1. but any more ideas?
hopefully its going to be like this except on my 2ltr.
http://freespace.virgin.net/josh.bowler/temp/test4.MOV
hopefully its going to be like this except on my 2ltr.
http://freespace.virgin.net/josh.bowler/temp/test4.MOV
06 January 2006, 01:31 PM
#4
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I agree with Ali, No. 1 looks the most convemient way, but maye No 2 would be more efficient. I assume the carburettor will be on the suction side of the supercharger which removes the problems with float chamber pressurisation.
I turbocharged my race egine like that except I was using fuel injection and throttle slides which was a lot easier.
Good luck with it
Les
I turbocharged my race egine like that except I was using fuel injection and throttle slides which was a lot easier.
Good luck with it
Les
06 January 2006, 03:04 PM
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I suggested Montego/Maestro Turbo SU's; Id be more concerned about how I was going to lower the compression ratio to about 8:1 before I worried about plenum chambers.....
Simon
Simon
06 January 2006, 03:43 PM
#7
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copper gasket, chamber increases. not the hard bit. Im using a metro turbo carb as someone suggested to me. (cheers fella) Its 44 HIF pressure sealed with manual choke (perfick)
So 2 would be more efficient. I dont care how I do it as long as its the best way. Ill make the f*&ker fit.
cheers guys this is really helping!
So 2 would be more efficient. I dont care how I do it as long as its the best way. Ill make the f*&ker fit.
cheers guys this is really helping!
Last edited by Poor Guy; 06 January 2006 at 03:47 PM.
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06 January 2006, 03:57 PM
#8
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Actually getting a lower compression ratio isnt the hard bit youre right. Lowering the compression ratio accurately, so that it doesnt pre-ignite itself to pieces within a few seconds is the hard bit. What compression ratio will you end up with? Unless you can tell me accurately and be certain that youre right Id worry more about that right now.
Good luck.
Simon
Good luck.
Simon
06 January 2006, 05:32 PM
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am going to drop it to about 130 PSI with the copper gasket. The guy in the video was running 11:1 compression ratio and about 8psi boost. God knows how it didnt blow up!
06 January 2006, 05:40 PM
#10
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Leslie, the carb is blow through Turbo SU. I dont want to be pressurising petrol and fuel. It gets me a little nervous. Plus washing oil off the charger internals aint good i dont think.
06 January 2006, 05:49 PM
#11
Just whack on a USA California spec cylinder head If CR becomes a problem. It uses some stupidly low compression ratio (as per the TR's )...8.5:1 IIRC.
Although I've seen both GT6s anTR's running over 10.5:1 normally aspirated, so the stock 9.5:1 CR should be ok provided you don't go overboard with the supercharger
Although I've seen both GT6s anTR's running over 10.5:1 normally aspirated, so the stock 9.5:1 CR should be ok provided you don't go overboard with the supercharger
Last edited by ALi-B; 06 January 2006 at 05:52 PM.
06 January 2006, 07:23 PM
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In that case Id look at a single Maestro Turbo sealed carb; as itll be jetted closer from stock and youll have a chance of setting it correctly.
06 January 2006, 07:35 PM
#14
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i have jets and needles at my disposal. remember, classic car owner here lol.
Before it runs with te charger its going to be sent to kingston racing down in birmingham for a rolling road setup. not worth spending money and time just for me to fire it up like a tw@ and destroy it all!
Before it runs with te charger its going to be sent to kingston racing down in birmingham for a rolling road setup. not worth spending money and time just for me to fire it up like a tw@ and destroy it all!
07 January 2006, 12:27 PM
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All understood Poor Guy, although they used to use superchargers with an SU on the induction side.
It is certainly important to lower the compresion ratio of course, and it usually yields more power with positive induction since it can push a larger charge volume into the cylinders.
I should have thought it might take a bit more than 3 psi without problems though.
Les
It is certainly important to lower the compresion ratio of course, and it usually yields more power with positive induction since it can push a larger charge volume into the cylinders.
I should have thought it might take a bit more than 3 psi without problems though.
Les
07 January 2006, 01:49 PM
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As long as you keep the boost sensible, I wouldn't have thought you'd need to lower the compression ratio. The GT6 engine is a pretty strong long-throw engine, not some Japanese buzzbox vibrating up and down at 10k rpm. Certainly you can supercharge an MX-5 with about 6psi boost without lowering the compression.
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