55mm or 60mm TB?????
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08-26-2006, 07:13 AM
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55mm or 60mm TB?????
Ok so I am looking into upgrading my TB and I have heard alot of people go for the MPx 60mm one, however when I read an article by Gary Howell it said that a 60mm was too big and would actually cut back power. Here is a part from the article.
What is considered "seriously changeing the air flow characteristics inside your engine?"
SO according to this the 55 is better, so what I am asking is since many of you have experience with these what have you heard or learned to be the best?
Here is the link to that whole page where I got that info, it really is a pretty comprehensive guide to "building a neon for performance" Hope it helps some of you out there.
Neon Guide To Performance
Adding a larger throttle-body from an automatic transmission Neon (52mm vs. 49mm) or boring your stock throttle body out will help boost output on a DOHC Neon by about 5 hp or more across the whole RPM range. RC Engineering and Howell Automotive can bore your stock throttle body out to about 57mm. You can also purchase billet throttle bodies from Modern Performance up to 60mm. Having a throttle body too big can hurt overall performance, so unless you seriously changed the air flow characteristics inside your engine, I wouldn't use anything bigger than 55mm throttle body.
Gary Howell wrote:
"49mm TB flows 252 cfm
52mm TB flows 283 cfm
55mm TB flows 317 cfm
60mm TB flows 377 cfm
At 8200 RPM a 122 cubic inch engine will need 290 cfm at 100% volumetric effiency, using the formula ((Max RPM/2)*Displacement)/1728. Rule of thumb is to go 10% over because a naturally aspirated engine can go above 100% volumetric efficiency because of cam overlap, header design, etc. Go above that and you kill low end because of reduced velocity, go below that you starve the engine for air at top end. 110% is volumetric efficiency is 319 cfm."
Based on this, 55 mm does seem to be the option for naturally aspirated (non-turbo) engines.
Gary Howell wrote:
"49mm TB flows 252 cfm
52mm TB flows 283 cfm
55mm TB flows 317 cfm
60mm TB flows 377 cfm
At 8200 RPM a 122 cubic inch engine will need 290 cfm at 100% volumetric effiency, using the formula ((Max RPM/2)*Displacement)/1728. Rule of thumb is to go 10% over because a naturally aspirated engine can go above 100% volumetric efficiency because of cam overlap, header design, etc. Go above that and you kill low end because of reduced velocity, go below that you starve the engine for air at top end. 110% is volumetric efficiency is 319 cfm."
Based on this, 55 mm does seem to be the option for naturally aspirated (non-turbo) engines.
SO according to this the 55 is better, so what I am asking is since many of you have experience with these what have you heard or learned to be the best?
Here is the link to that whole page where I got that info, it really is a pretty comprehensive guide to "building a neon for performance" Hope it helps some of you out there.
Neon Guide To Performance
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08-26-2006, 10:25 AM
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RE: 55mm or 60mm TB?????
Basically it goes like this stock...larger intake pipe ---> hits bottleneck in TB --->opens bigger through bellows tube --->slight bottleneck into manifold.
Now wouldnt it be better to take that middle bottleneck out of the line? And on a side note, i have never...NEVER heard of decreased performance after someone put in the 60mm TB (except on 2003 R/T's because the PCM sucks).
Now wouldnt it be better to take that middle bottleneck out of the line? And on a side note, i have never...NEVER heard of decreased performance after someone put in the 60mm TB (except on 2003 R/T's because the PCM sucks).