Larger Throttle bodies?
12-31-2007, 02:02 AM
#1
Three Wheelin'
Thread Starter
Larger Throttle bodies?
At what point does a larger throttle body make a difference?
Also what are some options for larger throttle bodies? Will the 968 Throttle body fit the 951 intake?
So school me on throttle bodies.
IPSC
Also what are some options for larger throttle bodies? Will the 968 Throttle body fit the 951 intake?
So school me on throttle bodies.
IPSC
12-31-2007, 02:58 AM
#2
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On our cars, the TB makes a difference up to a point where the intake manifold etc.. can't use all the air passing through it. If you port our manifolds, it would take a pretty good size TB to out flow it.
The idea that you don't need one on a modded engine is wrong. Sizing the TB to your needs is the hard part. You can not just build a manifold and put any old TB on it. It doesn't work that way.
The idea that you don't need one on a modded engine is wrong. Sizing the TB to your needs is the hard part. You can not just build a manifold and put any old TB on it. It doesn't work that way.
12-31-2007, 03:32 AM
#4
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Uh, if I had a $1 for that question, I'd be a millionare. You need to ask the builder of the intake what it was built for. There is not a magic TB for every manifold. I would assume someone did the testing before they sold the intake or I would assume you asked before you bought it. Hopefully it comes with a flowbench chart showing the two flowed together and then flowed while installed on your head. That way you can find out if its helping you or hurting you.
12-31-2007, 04:07 AM
#5
Listen to Dave. He knows from alot of Flow testing what goes on here.
I had a larger TB made. Its part of the parts list I had made. It fits onto a stock manifold with a new larger flange required.
Flow testing showed that the stock manifold is very inefficent in equalizing the flow to each runner. With a small mod, this can be changed and the larger TB helps if some other areas are also looked at. Larger TB's help in 2 areas. WOT and or part throttle. At part throttle the same throttle angle nets more volume of air passed. This helps increase the torque potential or I should say the less time required to reach the torque potential.
You must look at the other areas as well. Head Flow, manifold flow, exhaust flow etc. we saw in our testing, with the intake mod, the larger flange fitted and the larger TB, an increase in airflow thro the Head resulting in a reaaly good increase in torque. An engine that made 270 WHP @ 18psi now made 335 @ 16 PSI. It was found that the engine increased its VE from having all 4 cylinders obtain the same amount of air flow resulting in an increase in torque.
As stated, this was on our test engine. You need to have your head flowed with the manifold and TB fitted and from there make changes. I also remember flowing an aftermarket Intercooler backwards had an increase in flow. Our tests included the head with exhaust fitted, Intake, TB and Intercooler fitted with all pipes. We changed one part at a time and found where the problems were. Maybe its different on yours.
Listen to Dave and get his help here. He can save you a lot of $ and time finding what works.
I had a larger TB made. Its part of the parts list I had made. It fits onto a stock manifold with a new larger flange required.
Flow testing showed that the stock manifold is very inefficent in equalizing the flow to each runner. With a small mod, this can be changed and the larger TB helps if some other areas are also looked at. Larger TB's help in 2 areas. WOT and or part throttle. At part throttle the same throttle angle nets more volume of air passed. This helps increase the torque potential or I should say the less time required to reach the torque potential.
You must look at the other areas as well. Head Flow, manifold flow, exhaust flow etc. we saw in our testing, with the intake mod, the larger flange fitted and the larger TB, an increase in airflow thro the Head resulting in a reaaly good increase in torque. An engine that made 270 WHP @ 18psi now made 335 @ 16 PSI. It was found that the engine increased its VE from having all 4 cylinders obtain the same amount of air flow resulting in an increase in torque.
As stated, this was on our test engine. You need to have your head flowed with the manifold and TB fitted and from there make changes. I also remember flowing an aftermarket Intercooler backwards had an increase in flow. Our tests included the head with exhaust fitted, Intake, TB and Intercooler fitted with all pipes. We changed one part at a time and found where the problems were. Maybe its different on yours.
Listen to Dave and get his help here. He can save you a lot of $ and time finding what works.
12-31-2007, 04:19 AM
#6
Racer
Simon, would it be giving away secrets if I asked the mod, I have a hybrid 951 and S2 inlet manifold and I know that number 1 flows less than 2 & 3, with I think 4 flowing the most - guestimate from the colour of the cylinders heads & plugs.
rgds
mike
rgds
mike
12-31-2007, 04:28 AM
#7
Rennlist Member
Mike, so long as Dave doesn't mind I can show you some pics, and I know you're a real hands on guy, but I'd suggest talking to Dave and see what he can come up for you.
