widening intake
- Thread starter supra_man87
- Start date
If the stock flap style AFM is used, there is very little gain other than a cool, dense air charge. The stock AFM is the single biggest restriction in the N/A intake with stock cams.
Since you mentioned it Ma70, has anybody tuned in went to a larger TB, like the Q45, or Mustang TB? If so how much trouble to adapt from stock. With my set up, Maft-Pro SD, the TB is the most restrictive thing I've got left to replace. Any other ideas?Ma70.Ent;909007 said:
AJ'S 88NA;909023 said:
N/A TB Inner Diameter = 62-64mm or around 2.5 inches.
So yeah, it pretty much is the most restrictive thing, even more than the AFM. You know...tubbie is actually selling two different throttlebodies. One is a bolt-on 73mm TB (around 2.75 inches) and the other is a twin 56mm TB, based on a ford one, which means it uses oval piping and you'll need to run a custom throttle cable. Mustangs and ford trucks run oval piping. I was planning on buying one of them, but I don't know if I'll be able to do it now so it's up for grabs if you guys want to go for it
Another way to achieve oval piping if you're into custom work.
IJ said:
AJ
I would expect somewhere in the range of 2-10% gain with larger TB. Timing and cams are the next obstacle to take on to take advantage of these mods already in place. Of course this is speculation where the Supra is concerned based on other vehicles I have modded.
I would expect somewhere in the range of 2-10% gain with larger TB. Timing and cams are the next obstacle to take on to take advantage of these mods already in place. Of course this is speculation where the Supra is concerned based on other vehicles I have modded.
Ma70.Ent;909029 said:N/A TB Inner Diameter = 62-64mm or around 2.5 inches.
So yeah, it pretty much is the most restrictive thing, even more than the AFM. You know...tubbie is actually selling two different throttlebodies. One is a bolt-on 73mm TB (around 2.75 inches) and the other is a twin 56mm TB, based on a ford one, which means it uses oval piping and you'll need to run a custom throttle cable. Mustangs and ford trucks run oval piping. I was planning on buying one of them, but I don't know if I'll be able to do it now so it's up for grabs if you guys want to go for it
Another way to achieve oval piping if you're into custom work.
Tubbie?
it should be noted that when you increase the size of hte throttle body, the ECU thinks that you still have the same size TB (since you're using the stock TPS) and it assumes you're applying a given amount of load and air flow to the engine. I had a conversation with ED_Jza80 who built 7MA61's 7mge mk2 (has twin plate 57mm cobra throttle body on it) and he said he would get massive amounts of detonation at around 4000rpm at part throttle, sometimes at full throttle with the stock ecu. He suggested to not change the throttle body unless you have a standalone or sufficient means of adjusting for it.
Would tricking the ECU into thinking that it's running at a cooler temp to compensate for the fuel and using the turbo injectors that are 20cc or 40cc bigger than the stock N/A injectors work? Would the MAF mod help out too? Just kicking a few ideas around.
I run a 70mm BBK throttle on my NA.
And I have installed the weaker AFM spring from a 4AG flapper meter.
Stock injectors.
9" long K&N cone filter.
To tune it, I use a S-AFC, and a SARD FPR........
(and gauges so I know what the hell the engine is really doing)
No ping........
No problems.
And I have installed the weaker AFM spring from a 4AG flapper meter.
Stock injectors.
9" long K&N cone filter.
To tune it, I use a S-AFC, and a SARD FPR........
(and gauges so I know what the hell the engine is really doing)
No ping........
No problems.
If I remember correctly, the n/a injectors are around 330(318?)cc, while the turbo injectors are 440cc.
The maf mod of loosening the spring, so the door will open sooner. The only thing this does is cause a rich condition. I tested this(3 clicks back), and lost fuel mileage, with the only noticeable difference being heavy fuel fumes at idle, and black smoke at partial throttle. There's a good thread in here about this mod., and why it doesn't work, explained in detail by those much smarter than I.
The maf mod of loosening the spring, so the door will open sooner. The only thing this does is cause a rich condition. I tested this(3 clicks back), and lost fuel mileage, with the only noticeable difference being heavy fuel fumes at idle, and black smoke at partial throttle. There's a good thread in here about this mod., and why it doesn't work, explained in detail by those much smarter than I.
cuel;910100 said:
Yeah, just loosening the spring, without other mods to the AFM does nothing,
and will cause over-rich condition at idle.
And does very little to lessen the wide-open throttle air flow restriction caused by the stock spring on the AFM.
I run the light spring, with 2) .250" bleed holes in the flapper so it closes to the idle position when the engine is idling.
With the light spring, the AFM flapper goes wide open by 5000 rpm.
The stock spring will never reach wide open, even at 6500.
By the way, this is an impossible mod, if you don't have a S-AFC, an adjustable FPR, and a good A/F meter, like a GReddy or TOMEI to dial everything in with.
AJ'S 88NA;910078 said:
Yeah, it was a bitch !
I ended up machining off the ford TPS mount, and attaching one off the stock throttle.
The ford TPS is compatible with the Toyota system if you just add a separate closed throttle limit switch,
but I like to keep the system as close to stock as possible.
The linkage was also changed over to the Toyota bell crank,
but like other large throttles I have put on 7Ms,
the force to open the throttle was very high,
but once it opened, the required force drop dramatically,
making the throttle want to jump farther open.
This has to do with manifold vacuum having a larger area to act against the throttle plate,
and the fact that the BBK I used had an offset shaft (shaft was not exactly in the center of the throttle plate by almost 1/4").
Once the throttle opens, vacuum drops, and everything moves easier.
Made for a bitch driving through a parking lot slowly.
I cured this by reworking the bell crank so that it had more leverage at idle (offset shaft hole position)
and more movement after the throttle went off idle.
It took several different pieces of Toyota linkage, chopped & diced, then TIG welded together.
All large OEM throttles use this type of progressive linkage, including the Group-A 65mm throttle, and the Q45.
The BBK throttle I used was the one meant for the T-Bird Super-Coupe.
the bolt pattern is smaller than the mustang throttles, and easier to adapt to.
I just used a 1/2" aluminum plate, with the BBK pattern drilled & tapped,
right next to the Toyota patten, both in 6mm x 1 threads.
The plate attaches to the Y pipe with 4, 6mm cap screws from the rear passing through the stock threaded holes,
and the BBK bolts to the adaptor plate.
Then I blended the 70mm dia from the throttle gasket area down into the Y pipe opening with a die grinder, & abrasive flap wheels.
But there was still an interference with the right side cam cover.
To cure this, I had to machine the top of the cam cover by 1mm, and angle cut the Y pipe so it would tilt up by 5 degrees.
This gave me enough clearance to get the coupling hose & clamp on the front of the throttle.
I bought the BBK off eBay.
It had a broken throttle shaft, so I paid next to nothing for it.
Note: BBK will NOT sell you replacement parts !!
But it all worked out because when I went to make a new shaft,
I could make it just the way I needed it.