OFT and Grams throttle body

[86Speedy]

Yeah I love the TB instant throttle responce on NA

[Jeff Gray]

I have this coming and when it gets here I will do a same day dyno comparison on my N/A setup

[wparsons]

What most people pick up as an improvement on the butt dyno will be the increased airflow at smaller throttle openings.

I doubt at WOT there's a significant difference (ie greater than the margin of error on the dyno). At part throttle it'll feel like it's a lot faster since it's effectively giving more throttle than you're asking for.

[nikitopo]

This is what others suggested, but I'll have to wait till tomorrow.

[Evil Rocky]

Wondering on this as well.

[D_Thissen]

Originally Posted by nikitopo

This is what others suggested, but I'll have to wait till tomorrow.

If you can, do 3 runs before and 3 runs after the install. That should elimate some of the errors. I tossed my car on the dyno for fun a few years ago and 3 out of the 4 pulls had different results. The spread was about 3-5whp.

[nikitopo]

Originally Posted by D_Thissen

If you can, do 3 runs before and 3 runs after the install. That should elimate some of the errors. I tossed my car on the dyno for fun a few years ago and 3 out of the 4 pulls had different results. The spread was about 3-5whp.

I don't think that this difference is because of a dyno error. Keep in mind that if you do multiple runs on a dyno, then the actual air flow from the external fun is about 10 mph (and not 80 mph that you might have on road). This means that the radiator, oil cooler, and just about everything under the hood gets pretty hot. This heat reduces power in a number of ways. Not only is the air less dense, but like most modern cars the ECU pulls out timing. The coolant temp starts to rise, and sometimes that kicks on the cooling fan which sucks almost 3-5hp right there.

Overall, the bigger throttle body change is very popular in Japan. I t was mentioned quite a few times in the popular XaCar 86&BRZ magazine.

Check some pictures below:





What users are saying is that the throttle response is much better and there is also an improvement in torque and power. Personally, I'll only make a but dyno like a pull from 2k RPM in 6th gear and a few other tests. Another user mentioned that will make an actual dyno (before & after).

[wparsons]

Originally Posted by nikitopo

I don't think that this difference is because of a dyno error. Keep in mind that if you do multiple runs on a dyno, then the actual air flow from the external fun is about 10 mph (and not 80 mph that you might have on road). This means that the radiator, oil cooler, and just about everything under the hood gets pretty hot. This heat reduces power in a number of ways. Not only is the air less dense, but like most modern cars the ECU pulls out timing. The coolant temp starts to rise, and sometimes that kicks on the cooling fan which sucks almost 3-5hp right there.

That's assuming the power kept going down run after run, which is hardly ever the case. 3-5whp spread on multiple runs is actually pretty consistent.

[D_Thissen]

They may claim that they are making more power and are having better response, but like @wparsons said, it could be that the larger tb is able to intake a larger volume of air at partial throttle. So the car feels faster. At WOT, the engine can only ingest (and expel)so much air and unless the stock tb is limiting that amount, a bigger one shouldn't make a noticeable difference.

Fwiw the runs were done with the hood open and a large fan in front of the car.

[nikitopo]

Originally Posted by D_Thissen

They may claim that they are making more power and are having better response, but like @wparsons said, it could be that the larger tb is able to intake a larger volume of air at partial throttle. So the car feels faster. At WOT, the engine can only ingest (and expel)so much air and unless the stock tb is limiting that amount, a bigger one shouldn't make a noticeable difference.

Who knows, maybe they made it because at WOT the throttle body is not opening a 100%. Here is an old post from @wparsons questioning about this issue http://www.ft86club.com/forums/showthread.php?t=62023

... or maybe because the stock tb is actually a limiting factor.

I am not the one who will question XaCar or respected engine builders.

[wparsons]

^^ If you found that thread, I assume you also found this image in it?



Even at a 90-92% opening, it's still flowing almost 100% of the air as if it were open 100%.

It has been proven by multiple tuners on multiple dynos that on almost any N/A car, or even lightly boosted, the TB is not a bottleneck. It's 65mm stock, which is pretty large for a 2L N/A engine. Lots of other 2L cars upgrade to smaller than what we have stock.

[D_Thissen]

I can't read Japanese (I'm assuming that's what it is) but are they talking about a car that's NA, or one that's FI? There is a video online of boosted car picking up 10+whp. While it is a gain, 10whp on a 300whp isn't very much (~3%) and that car has full bolt-ons, running E72. I haven't seen NA one...yet.

I'm not trying to be hater or anything, I'm just trying to be realistic. I could see it being a good part for someone who is a diehard NA fan who plans on doing valve train work, port polished heads etc. For more 86 owners (and price), an OFT would be more beneficial.

[imnotsureaboutbrz]

in for results. I'm waiting (likely for a long time) to see someone take a 2017+ intake and have to port matched to that throttle body and see what changes happen.

[Kodename47]

Originally Posted by nikitopo

Who knows, maybe they made it because at WOT the throttle body is not opening a 100%. Here is an old post from @wparsons questioning about this issue http://www.ft86club.com/forums/showthread.php?t=62023.

On EcuTek it shows ~80% at WOT but all that determines is that the TPS is at ~4v (0.8x5). I've verified this before. All someone needs to do is take the intake boot off the TB and look what happens when you jump on the pedal, it'd be pretty obvious if it doesn't open 100%.