LT1 Throttle body and mods
02-11-2004 | 05:08 PM
#16
Rennlist Member
Joined: Feb 2003
Posts: 29,958
Likes: 185
From: saratoga, ca
also, as I have calculated, the area of the new LS1 intake throttle body is actually less than a stock US throttle body. (ie 5.6 square inches) this is because each one of the two LS1 TBs is 48mm , even at 52mm X 2, the square area is still in the 6 .5square " range.
A euro throttle body is 7 square inches and is done in a single opening, vs the oval dual throttle body tube that will not flow as efficiently as a single opening.
Plus, all the stuff you have mentioned below, make the new config, less eff and benificial to the 2 valve intake. However, for making it all fit with the supercharger installation, it would be worth any losses vs the stock US stuff.
remember, I still got 292 hp to the rears with the stock AFM. most all 85s cant even post this high of a number with a MAF system!!. (ie block is the same and the 85 has 4 valves!!!)
the euro stuff is pretty darn good!!
MK
A euro throttle body is 7 square inches and is done in a single opening, vs the oval dual throttle body tube that will not flow as efficiently as a single opening.
Plus, all the stuff you have mentioned below, make the new config, less eff and benificial to the 2 valve intake. However, for making it all fit with the supercharger installation, it would be worth any losses vs the stock US stuff.
remember, I still got 292 hp to the rears with the stock AFM. most all 85s cant even post this high of a number with a MAF system!!. (ie block is the same and the 85 has 4 valves!!!)
the euro stuff is pretty darn good!!
MK
Originally posted by gbyron
Bill,
'Non-symmetrical' in this scenario means that there is not a (basically) equal distance between the air inflow (in this case, TB) and the outflow (the runners).
A factory 951 intake feeds air in the front, into the 'log', then the cylinders grab what they can. The problem is, they don't all get a fair shake in the 'air grab'. The guys up front get the best access, and take all they can. The guys at the back get the scraps. Feed it in equidistant from all the cyls. and everybody gets (essentially) the same shot at the air; they may not get all they could take, but they all get about the same.
The factory 928 (2 valve) manifold actually is relatively efficient in this manner.
As in (though likely not as bad as) a 951 factory manifold, one is feeding the air in very close to some cylinders, and (relatively speaking) farther away from others.
This leads to a scenario where the airflow is unbalanced, ie, some cylinders will get better flow than others by virtue of their place 'in line' as it were.
The cylinders at the back of the line, will not flow air at the same rate as the ones at the front, even under boost.
But it does look neat, and may solve a particular packaging issue that is more important to the user than the loss of performance compared to a symmetrical intake.
Greg
Bill,
'Non-symmetrical' in this scenario means that there is not a (basically) equal distance between the air inflow (in this case, TB) and the outflow (the runners).
A factory 951 intake feeds air in the front, into the 'log', then the cylinders grab what they can. The problem is, they don't all get a fair shake in the 'air grab'. The guys up front get the best access, and take all they can. The guys at the back get the scraps. Feed it in equidistant from all the cyls. and everybody gets (essentially) the same shot at the air; they may not get all they could take, but they all get about the same.
The factory 928 (2 valve) manifold actually is relatively efficient in this manner.
As in (though likely not as bad as) a 951 factory manifold, one is feeding the air in very close to some cylinders, and (relatively speaking) farther away from others.
This leads to a scenario where the airflow is unbalanced, ie, some cylinders will get better flow than others by virtue of their place 'in line' as it were.
The cylinders at the back of the line, will not flow air at the same rate as the ones at the front, even under boost.
But it does look neat, and may solve a particular packaging issue that is more important to the user than the loss of performance compared to a symmetrical intake.
Greg
