Hemi Truck Club banner

1 - 20 of 41 Posts

·
David
Joined
·
2,229 Posts
Discussion Starter #1
I have a Fastman standard bore 85mm ported TB. It is not ported on the back side. When I bought it all I had was intake and exhaust. After talking to Dan he advised not to get his performance TB as I didn't have enough mods to warrant the extra porting. Now I have BV Heads and Cam upgrade. Would it be worth the coin to upgrade to a true 90mm TB? I know I'd have to open up the intake to take advantage of this. May even go to a Vararam also.
 

·
Registered
Joined
·
1,978 Posts
Bigger is not always better. Your engine can only ingest so much air and fuel. The air velocity will slow down at the hit, but you'll probably see better gains upstairs. If it were me, I'd stick with what you have.
 

·
David
Joined
·
2,229 Posts
Discussion Starter #3
That seems to be the consensus. I plan on calling Dan on Monday. I have the standard bore which retains the factory throttle blade. He was very helpful when I ordered my first TB. And talked me out of the performance bore TB.
 

·
Greg
Joined
·
19,956 Posts
I guess I'm going to be the odd duck here. I first stuck a 90mm (cable drive) on my 5.7 when I installed the Megasquirt stand alone ECM. The tune was exceptionally strong and responsive from launch to 7000. I didn't know to attribute this to the Tune or the 90mm. I removed the Megasquirt ECM and went back to my old FastMan (FBW) TB and a factory PCM (auto) flashed for 750 idle, 7000rpm/140 speed limiter with a cmr tune. It ran really good but not as explosive as with the Megasquirt. I then installed a 90mm BBK and the performance was back. Unfortunately I lost that tune when I reflashed that PCM to manual and haven't been able to replicate it since. Point I'm trying to make is that there is a tune using a 90mm TB that is very hot. Recovering that state of tune is my current quest utilizing the 90mm which in my mind is key to this success. Good luck...
 

·
Registered
Joined
·
152 Posts
Is the gain between an 85, 87, and 90mm TB incremental? As in they will all go up with the bigger size or does each one have a different characteristic?

I'm looking at getting a new TB as well and can't dig up enough information. But the elevation here in Colorado and when I go up to the mountains can be crazy thin air and you can tell how much it effects your car. I am guessing a bigger one would help get more air in and help performance up in elevation as well?
 

·
Registered
Joined
·
610 Posts
I have a 90mm BBK on my 06. The truck also has a superchips 91 tune on it along with other mild up grades. I love the 90mm! The throttle response is great! I have to admit if I build up this motor much more I will start looking into a 100mm! Keep in mind my truck has stock cam,heads,and so on. I think it all comes down to how many RPMS you want to run. The more RPMS you rev and stronger the pull on the throttle body will be.
 

·
Registered
Joined
·
152 Posts
I have a 90mm BBK on my 06. The truck also has a superchips 91 tune on it along with other mild up grades. I love the 90mm! The throttle response is great! I have to admit if I build up this motor much more I will start looking into a 100mm! Keep in mind my truck has stock cam,heads,and so on. I think it all comes down to how many RPMS you want to run. The more RPMS you rev and stronger the pull on the throttle body will be.
Right now I have a hemifever 91 tune, Volant intake, Corsa exhaust, and a Sonnax. I sent an email to Sean to see what he thinks. Will diameter of the new TB be the same so I can use my intake and the stock air baffle that says "HEMI" on it?

Which TB did you go with?
 

·
Registered
Joined
·
610 Posts
Right now I have a hemifever 91 tune, Volant intake, Corsa exhaust, and a Sonnax. I sent an email to Sean to see what he thinks. Will diameter of the new TB be the same so I can use my intake and the stock air baffle that says "HEMI" on it?

Which TB did you go with?
My TB is a BBK. and I have a mopar CAI and it works great with the bigger TB. I don't see why yours wouldn't work!
 

·
Registered
Joined
·
223 Posts
Fastman 84 mm will handle anything you throw at it boss. Many mid to low 12 second all motor trucks running them and a few that are still running the factory TB. Randy hall ran a 11.98 in his 06 qc on his stock throttle body with cam and heads on nitrous. There might be a few horse power to be had from a lot bigger throttle body like a 90mm but air velocity down low in my mind would loose a lot of velocity and low end torque. Even LS based performance shops steer away from FAST 90mm throttle bodies unless you are Cammed with larger stall and have the rpm to utilize it or Have forced induction. Just my 2 cents
 

·
Slow Memeber
Joined
·
5,510 Posts
Stock tb here with a baby cam/headers/tune/ an used to have converter lol. Maybe it would help my truck but could never justify the price for one
 

·
Registered
Joined
·
209 Posts
I know this is an old post, and some may have seen my post in the hemi sports thread. I'm looking to mod my 04 HS, looking to start with a throttle body. This is my daily driver once I get laid off for winter. My HS is a 4x4 and I also you this to pull my duck boat with so not sure where to start when it comes to TB. Any recommendations on size and maybe what to pair it with to get the most bang for my bucks?
 

·
Matt
Joined
·
2,658 Posts
When I do mine it's going to be an 87mm. 85 is better than stock and if you're only going to do a few mods is plenty fine. The 87 give you the freedom to go farther with mods if you want and for the price difference I don't see the need to buy a second one down the road unless it fails. You have to do quite a bit to the truck before you'll notice a difference between the 87 and 85.
 

·
Administrator
Joined
·
17,796 Posts
The 87mm tapered bore is what I woukd go with. 90 is more for boost and big crazy engines. The 87mm is a tapered bore so it actually speeds the air charge a little rite at the throttle body.
 

·
Registered
Joined
·
209 Posts
Thanks for the info guys. I pretty much intend to do the same as everyone else TB, intake, induction, headers , hi flow exhaust, programmer, maybe transmission cooler or something along those lines help expand the life. Down the road possibly do a can but that's not a for sure thing. I run into a problem with exhaust though because I actually don't mind the ground effects but I can't find the skirt with the cut for the driver side online. Possibly something I have to get at the dealership? Or maybe run both to one side with a dual tip.
 

·
Registered
Joined
·
209 Posts
That's what I was planning on originally and I got to reading about H pipe and X pipe and crack pipe and all sorts of stuff haha. I was thinking magnaflow, my friends got that set up on his and it sounds decent. I like a nice rumble , don't need the loud kackle like the high school kids around my area want.
 

·
Enormous Member
Joined
·
1,154 Posts
The 87mm tapered bore is what I woukd go with. 90 is more for boost and big crazy engines. The 87mm is a tapered bore so it actually speeds the air charge a little rite at the throttle body.
look at my mods, 87 for me too ?
 

·
Premium Member
Joined
·
9,537 Posts
The 87mm tapered bore is what I woukd go with. 90 is more for boost and big crazy engines. The 87mm is a tapered bore so it actually speeds the air charge a little rite at the throttle body.
What constitutes BIG & CRAZY


:eek:ld-025:
 

·
Registered
Joined
·
209 Posts
Don't run dual exhaust it kills the hemi low end torque. Run a 3" y pipe and the muffler you want.
What about headers. I've read other threads and have gather long tube is the way to go. And then is it better to piece it together or find a full CB system?
 

·
Greg
Joined
·
19,956 Posts
1 - 20 of 41 Posts
Top