Throttle body kits?
- Thread starter Lewis.
- Start date
The gains with throttle bodies are with setups with a body per cylinder, as this reduces the gap between the body and the cylinder, thus improving throttle response. Whilst still maintaining and/or improving air speed. The enlarged original throttle bodies you can get mean slower air speed which will reduce the torque output. The simple way to remember what you need, (this applies to exhaust system diameters as well as inlet diameters) you want the smallest ones that are big enough.
Too small will restrict the amount of air you can get in but too big will reduce the speed of the air flowing through and reduce the torque output which will contribute to reducing the power output.
I don't know what you already know but to get a certain amount of air through a 100mm hole in 5 seconds the air will only be travelling half as fast as if it were to get through a 50mm hole in the same amount of time.
It all sounds complicated but once you've got your head round it it is very simple.
I haven't had any experience with fitting throttle bodies to these engins but I have spent a lot of time with fitting them and motorbike carbs to ford and honda engines. The more strung out the engine is with lairy cams and high compression pistons and so on the bigger the advantage they create. I don't know if jenvey, or active technologies do anything for this engine or if not it may be possible to get dcoe manifold throttle bodies and have a manifold made, though generally direct to head bodies are superior.
I would recommend active technologies as their quality is second to none and there is no shaft to disrupt and slow airflow in their bodies butterfly valves.
Too small will restrict the amount of air you can get in but too big will reduce the speed of the air flowing through and reduce the torque output which will contribute to reducing the power output.
I don't know what you already know but to get a certain amount of air through a 100mm hole in 5 seconds the air will only be travelling half as fast as if it were to get through a 50mm hole in the same amount of time.
It all sounds complicated but once you've got your head round it it is very simple.
I haven't had any experience with fitting throttle bodies to these engins but I have spent a lot of time with fitting them and motorbike carbs to ford and honda engines. The more strung out the engine is with lairy cams and high compression pistons and so on the bigger the advantage they create. I don't know if jenvey, or active technologies do anything for this engine or if not it may be possible to get dcoe manifold throttle bodies and have a manifold made, though generally direct to head bodies are superior.
I would recommend active technologies as their quality is second to none and there is no shaft to disrupt and slow airflow in their bodies butterfly valves.
Generally speaking there's very limited space between head and slam panel ( which is integral to structure so can't be removed like then mk2 clios ) to fit long trumpets so shorter versions must be fitted which do restrict torque.
Going on from there you'll want to run some wild cams to make the most of the ITBs however piston clearance is another limiting factor so forged pistons with deeper valve pockets must be fitted, at this stage VVT should also be deleted as the extreme lift with result in a very short dephaser life span. This further reduces mid range torque.
the engine becomes all about top end power so fit some ARP rod bolts and raise the limiter to 7800rpm. I ran this spec and with supporting mods ( exhausts, decats, oil coolers, ignition etc ) achieved 230bhp. There were plans to fit a custom slam panel to allow the trumpets to be extended right upto the bumper but before these were put into action TDF went race car only and I sold up for turbo power.
Look at AT power for throttle body kits, if they're even still trading.
For this level of build budget 10-12k
Going on from there you'll want to run some wild cams to make the most of the ITBs however piston clearance is another limiting factor so forged pistons with deeper valve pockets must be fitted, at this stage VVT should also be deleted as the extreme lift with result in a very short dephaser life span. This further reduces mid range torque.
the engine becomes all about top end power so fit some ARP rod bolts and raise the limiter to 7800rpm. I ran this spec and with supporting mods ( exhausts, decats, oil coolers, ignition etc ) achieved 230bhp. There were plans to fit a custom slam panel to allow the trumpets to be extended right upto the bumper but before these were put into action TDF went race car only and I sold up for turbo power.
Look at AT power for throttle body kits, if they're even still trading.
For this level of build budget 10-12k
TB Rich
Paid Member
Extreme lift will cause issues with hydraulic tappets, never heard it cause issues with vvt. Extreme overlap though, and you might as well ditch vvt because even that won't stop enough reversion back up the inlet port from the late IVC point after BDC.
12.2mm is the most lift you want to run in these, for 12.5mm you need solid and lash caps etc.
The standard roller follower is ok for up to 8k and then beyond for reliability you want to replace that part too.
Are you sure about the top slam part being structural, I've seen loads of mk3 race cars with it removed. But as yet I've no quantified research on this.
12.2mm is the most lift you want to run in these, for 12.5mm you need solid and lash caps etc.
The standard roller follower is ok for up to 8k and then beyond for reliability you want to replace that part too.
Are you sure about the top slam part being structural, I've seen loads of mk3 race cars with it removed. But as yet I've no quantified research on this.
Thanks guys. I'm aware of what throttle bodies do I just wanted to know what kits are available as above, and of the gains are worth the outlay etc. for example on some of the older saxo engines you could get quite good midrange improvement whilst retaining the standard internals. My Rallye has bodies and is seriously modified so if I did similar on the Clio would rather keep it closer to standard but with improved driveability etc. thanks!
TB Rich
Paid Member
The mk2 clio (F4r73x) responds well (like the TU5's you mention) because the stock inlets are crap. The mk3 Clio (F4R83x) inlet however is better so the gains are of course less. There have not been many/any cars to be able to quantify what the gain are. Off the top of my head there was Ben's car but little supporting dyno info. And a competition car on here but again no back to back power data vs the standard inlet.
all of this doesn't touch on the ECU of course though, you'll need an ECU to run TPS with bodies, and as to how much/if any of the standard dash you want to retain -makes it more or less expensive/complicated.
The canbus on these cars make it much more complicated than just bashing in a DTA like we did with Saxo's/106's and run a new wire from speed sensor direct to the back of the dials (rather than where the OEM ECU no longer was)!
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