I currently have an LX 253, pretty standard, with quadrajet, slightly larger cam and straight through exhaust.
Just wondering what the benefits of using a tunnel ram on this would be
Such as: http://www.gmh-toran...?showtopic=1213
Also wanting to know what other mods would be required, and whether this would be a legal modification in NSW.
Any help appreciated.
Cheers
Tunnel Ram - Worth It?
Started by
_77LX253_
, Jan 14 2006 10:05 PM
4 replies to this topic
#2
_82911_
_82911_
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Posted 14 January 2006 - 10:51 PM
Illegal, and IMHO a total waste of time...
LOOK BLOODY ORSOME though!!
Cheers Greg..
LOOK BLOODY ORSOME though!!
Cheers Greg..
#3
Stedz_lc
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Posted 15 January 2006 - 08:28 PM
Why illegal?
Must say they do look fukn hot id have one but the fat P plate giv's me enough worrys
Cheers
Ed
Must say they do look fukn hot id have one but the fat P plate giv's me enough worrys
Cheers
Ed
#4
Struggler
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Posted 15 January 2006 - 09:22 PM
I will share with you some of my tunnel ram experience...
I recently fitted a Edelbrock Street Ram and 2x 450 Holleys to my 355 SBC (previously RPM Air Gap and 750 vac equipped). Last runs were made in winter were it ran 11.95 @ 112. With the ram and no other changes it slowed to 12.1 @ 112 in 38 degree heat. Both combos were optimized on a chassis dyno with an O2 sensor before raced.
What this proves is that I probably lost some mid range torque but picked up some real horsepower (in fact it was faster in the second half of the track than ever before). On a cold night I reckon the ram would flog the previous combo. On the street the lack of torque is unnoticeable, however once at WOT it is a bit doughy until the revs pick up. I believe it has some atomization issues that only occur at WOT that are cured with the greater air flow that more revs provide (vac sec carbs would fix this by opening the secondaries a bit more progressively). I must say it does look great though, it really turns some heads !!!
Personally I reckon I need some more cubes to really get the most out of it, or a smaller runner in the manifold. I have dropped the diff gears from 3.70 to 4.11 and will retest it soon. Hopefully this will keep the revs up enough to see me through the doughy spot.
Anyway.... a 253 with a tunnel ram could be a real pain, it might be acceptable with a pair of 390 vac secs, or even a pair of Qjets with the secondary air valves super tight. Either way you will have to play with it to get it acceptable. Is it worth it ?.... Only you know the answer.
I recently fitted a Edelbrock Street Ram and 2x 450 Holleys to my 355 SBC (previously RPM Air Gap and 750 vac equipped). Last runs were made in winter were it ran 11.95 @ 112. With the ram and no other changes it slowed to 12.1 @ 112 in 38 degree heat. Both combos were optimized on a chassis dyno with an O2 sensor before raced.
What this proves is that I probably lost some mid range torque but picked up some real horsepower (in fact it was faster in the second half of the track than ever before). On a cold night I reckon the ram would flog the previous combo. On the street the lack of torque is unnoticeable, however once at WOT it is a bit doughy until the revs pick up. I believe it has some atomization issues that only occur at WOT that are cured with the greater air flow that more revs provide (vac sec carbs would fix this by opening the secondaries a bit more progressively). I must say it does look great though, it really turns some heads !!!
Personally I reckon I need some more cubes to really get the most out of it, or a smaller runner in the manifold. I have dropped the diff gears from 3.70 to 4.11 and will retest it soon. Hopefully this will keep the revs up enough to see me through the doughy spot.
Anyway.... a 253 with a tunnel ram could be a real pain, it might be acceptable with a pair of 390 vac secs, or even a pair of Qjets with the secondary air valves super tight. Either way you will have to play with it to get it acceptable. Is it worth it ?.... Only you know the answer.
#5
_[BOTTLEDUP]_
_[BOTTLEDUP]_
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Posted 16 January 2006 - 10:32 PM
On a 253 forget it. Unless you have the bottom end strength that will handle turning past 8000rpm all you will be doing is stepping backwards. A 253 won't pull hard enough on the runners to make any airspeed.
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