63mm Throttle Body

[gixrman]

1. Bigger TB is not a proven performance on "all" vehicles. By that, I mean bigger TB doesn't alway equates to better performance. It depends on the rest of the setup.

2. It will not help spool up unless 60mm TB is restrictive.

3. You can find a stock 60mm TB for $50, 100% bolt-on and performs as great.

And this is very true on a 2g were the TB does become a bottle neck.

 

[Turbo Monk3y]

Steve does a great job, my 66.5mm 1G is awesome and idles great even with the FIAV block off.

He will go bigger if you want, which is great for us with the JM intake mani.

I want to know more of this 66.5MM 1g one as I have been looking for a good medium. I have an Anodized black Magnus SMIM and want just about 5mm more than the 60mm... This sounds just like the perfect medium.. I read somewhere that boring over 63mm gets rid of the lip inside of the throttle body which creates horrible idling problems, Since I have dsmlink with Simulate IdleSv I'm sure this wouldnt be too much of a problem... Let me know if its really bored out that big or you are just estimating its flow due to a half shaft mod or something...

 

[thegchild04]

I want to know more of this 66.5MM 1g one as I have been looking for a good medium. I have an Anodized black Magnus SMIM and want just about 5mm more than the 60mm... This sounds just like the perfect medium.. I read somewhere that boring over 63mm gets rid of the lip inside of the throttle body which creates horrible idling problems, Since I have dsmlink with Simulate IdleSv I'm sure this wouldnt be too much of a problem... Let me know if its really bored out that big or you are just estimating its flow due to a half shaft mod or something...

I am going to get the Link in the spring and I want to get a bigger throttle body possibly without a ISC but I blocked off the FIAV with a plate on my current t/b and it doesn’t idle as good as it would if the ISC was connected.

So my question to you is will the Simulate IdleSv option in dsmLINK eliminate the cold start idle problems the car has without the ISC. I am searching and searching and I can find any answers. I wish I had a dsmLINK forum account.

 

[stevemonroe]

Going past 63 mm on a 1G can cause several problems TBs are casting and the wall thickness can vary from one to the next.
Not long after I did the 66.5mm for Mike I bored through the walls on another one at 66mm and ruined it. I'd say 65mm is the limit to be safe now but it requires extra work and costs an additional $50.
There are downsides too; As mentioned it can affect idle when the baffle by the FIAV ports is cut away. One more thing is that often the casting is softer in the middle than it is near the outer wall. That causes a poor surface finish. I don't list the 65mm option on my website but it can be done on request.
Thanks
Steve

 

[Car Cannibal]

"1. Bigger TB is not a proven performance on "all" vehicles. By that, I mean bigger TB doesn't alway equates to better performance. It depends on the rest of the setup.

2. It will not help spool up unless 60mm TB is restrictive."



1) By all vehicles, I am referring to performance oriented ones that would even think of doing this mod. I have done ported TB's on many performance cars, some not even turbo charged and ALL OF THEM SHOWED A NOTICEABLE DIFFERENCE. Try running one on just one car and let us know what it is like in the real world.

2) The spool up was noticeable, even on the stock intake. Throttle response was noticeable on a N/A 350 Trans Am, it was noticeable on an 87 Grand National etc etc all with stock intakes. The Trans Am was not a mildly modded car either and it was clear as day it started moving faster when you nailed it.

I don't recommend you do the ported TB first, but it works when you slap it on.

Hey Steve, hows the biz??

Steve, with the half shaft mod, you generally gain the flow of a TB 2-3mm bigger correct??

About 7k on the 66.5mm TB and all is well so far.

 

[stevemonroe]

Hi Mike, Yes, the half shaft is safe even on a turbo car and makes a significant difference. The CFM gain is measurable by figuring the cross scection of that part of the shaft that gets removed and adding that to the bore area. My math showed that a 63mm TB w/a 10mm shaft will flow about the same CFMs as a throttle body that has a 65.5mm bore and I've done more than 400 half shafts with no failures. (Hope I'm not spamming you guys here )
Thanks
Steve

 

[nanokpsi]

I've never really understood the point of boring the TB over to 63mm or just going with a larger TB all together unless you are trying to make stupid amounts of power, i.e. +700whp. I've just seen way too many DSMs make 500-680whp on a 60mm TB.

You'll see JP, I'll make 709whp and it will all be thanks to my Q45 tb

I think you're right though. Most people dive into these upgrades thinking they will get a bunch of power out of them and its just not the case. I only went the route I did becasue I fall inot the "crazy amount of power" category amd I new I was going to run 3" ic piping. The q45 unit was also cheaper than the mustang units Ebay FTW

 

[pneumo]

I took a couple pics to help illustrate the difference between the stock TB and the Q45 TB. I appreciate Hal's pic, but thought it lacked perspective. I know the first pic shows the stock TB elbow, but I wanted to include it since I was able to do the 11 second run in my profile with it. It's amazing how much power can be made with such a restriction, just as long as it's the ONLY restriction.

With a Q45 TB you'll never have to wonder if it's too small.

 

[thegchild04]

^^^ thats crazy

 

[ckeins]

do these TB work with the stock ISC stepper?

 

[GRNDSM]

OK, so what are you trying compensate for?

Seriously, I am yet to see anyone back up the “more power” claims from a bigger TB… And I am not interested in an anecdotal evidence…

I chose to stick with a stock TB for the following reasons:

1. It is the MOST reliable TB available! This is a very big issue!
2. I didn’t see any evidence that would give me more power.
3. I saw plenty of other guys making 600-700whp on a stocker.

My guess is that I could have picked up 20-30hp form a bigger TB and a larger upper I/C pipe. But I didn’t trust any aftermarket options so I stuck with the 60mm and 2.5” upper I/C pipe.

But if you guys feel like you need to upgrade at ~400-500hp level, then go for it!

 

[thegchild04]

OK, so what are you trying compensate for?

Seriously, I am yet to see anyone back up the “more power” claims from a bigger TB… And I am not interested in an anecdotal evidence…

I chose to stick with a stock TB for the following reasons:

1. It is the MOST reliable TB available! This is a very big issue!
2. I didn’t see any evidence that would give me more power.
3. I saw plenty of other guys making 600-700whp on a stocker.

My guess is that I could have picked up 20-30hp form a bigger TB and a larger upper I/C pipe. But I didn’t trust any aftermarket options so I stuck with the 60mm and 2.5” upper I/C pipe.

But if you guys feel like you need to upgrade at ~400-500hp level, then go for it!

id say it would be a good mod for a 2g, to put maybe a 1g t/b on. but for me to do a 75mm t/b and 3' pipe that seems pointless. plus I have always used the school of thought that with less volume from the turbo to the intake manifold the less the pressure drop you would see. Not only that now I am starting to see a lot of movement from air - air to liquid – air cooling and making very nice power on these “newer” setups which uses a lot less volume.

 

[pneumo]

do these TB work with the stock ISC stepper?

No the Q45 TB has a screw to adjust idle.

 

[pneumo]

I chose to stick with a stock TB for the following reasons:

1. It is the MOST reliable TB available! This is a very big issue!
2. I didn’t see any evidence that would give me more power.
3. I saw plenty of other guys making 600-700whp on a stocker.

My guess is that I could have picked up 20-30hp form a bigger TB and a larger upper I/C pipe. But I didn’t trust any aftermarket options so I stuck with the 60mm and 2.5” upper I/C pipe.

From my experience you were right to stick with a stocker for reasons of reliability.
My Q45TB is sticking slightly, preventing it from closing completely. Whenever I go WOT the shaft gets pulled sideways somehow, and the throttle plate hits the side of the bore. It's OK if you like 3k rpm idle. I don't know if others have run into this issue, but I'm gonna swallow my pride and admit that it's not all good. I'll tear it apart soon and see if it's fixable.

 

[GRNDSM]

That is interesting... I thought that Q45 TB was the first reliable ulternative. Looks like that might not be the case . Keep us updated!

 

[oldman]

Power gains aside, Steve does great work. My 90 TB was the first 63mm 90' Steve did, initially there were some plate sticking issues due to 90' being different from 91'+, Steve took the TB back and fixed it no questions asked. It's one thing to produce a good product, it's another to stand behind it, something rarely seen these days.

 

[pneumo]

I finally found a fix for the sticking Q45 TB. It seems the bearing cup located under the linkage is just lightly peened in place. Under boost the pressure pushes the cup out a little, pulling the shaft sideways, which is why the TB plate sticks. So I fixed it by first disassembling the TB. I used two part epoxy to bond the cup into place, then peened it down in a few extra locations. Then just reassemble it.

The stock Q45 TB works just fine with low boost, no problem with light throttle driving. I drove for hours around the city with no issues. It only started sticking when I did a full 2nd gear pull over 21 psi of boost. Just in case my TB might have been bad/defective, I bought another one and it did the same thing. Now that I know how to fix it for high boost I won't need a spare TB anymore.

I tested it tonight by doing about 10 full WOT pulls at 26psi of boost in second and/or third gear. What a blast! I know Kumho MX's aren't the best in cool weather, but it's so much fun breaking all 4 tires loose in second gear on dry pavement and feeling the back end wiggle around!

I know you're all concerned about the durability of the Q45 TB, so I guess I'll do my duty and keep testing it at higher boost. I'll let you know how it holds up to 30 psi next!