85 or 90 mm TB??

[Chris]

I know BBK makes an 85mm. I'm not sure who makes a 90mm. Would I need to retune?

 

What would be the benefits/downside

 

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[BlackZ71Silverado]

Not exactly sure about the retune but people with the 5.3L have been putting a 90mm TB (from a Vette) on these trucks without issue. They have reported better throttle response. Dhould be same for your engine. Pretty sure there are some topics around here is you do a search, been a while since I have seen one.

 

 

 

AcDelco Part #217-3153 (LS3,LS7,L99)

 

 

What size does your 4.8 come with from the factory?

[Chris]

That's my next question. I have my replacement autocal now and I'm going to retune to change from 265/75r16 to 275/55r20 even though there isn't much difference. Just looking at ideas. My next step is a 300 amp alt and big 3. But was going to do the TB if I find a deal. I figure maybe an LS6 TB. But I'm not sure.

 

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[BlackZ71Silverado]

Check ebay, there are a few there for sale right now. $141

http://www.ebay.com/itm/LS3-LS7-L99-90mm-Throttle-Body-Corvette-Camaro-SS-Z06-G8-NEW-GM-12605109-Gold-/190698569801?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3ACorvette&hash=item2c66854049&vxp=mtr

[Chris]

I know there is a difference between Gen 3 what I have and what everyone else on here is using

 

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[Chris]

thinking of the FAST LSXrt manifold too if it is ca legal. And I don't have the tools or knowledge on what has to be done to port. I have an air compressor and a die grinder. But no bits

 

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[Ryan00TJ]

IMO Not worth it adding the 90mm TB unless you add the LSX 90mm intake to match. I ported my LS1's 75mm TB on the stock LS6 intake manifold. Mainly blended the transition and smooth the surface. Supported 420rwhp in the SS.

[Chris]

I'm looking onto the lsxrt manifold as well and possibly their 92 mm TB. Just not sure how much benefit it will be and if its California legal. The factory size is 78 mm I believe

 

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[BlackZ71Silverado]

^^^^^^^^^^^^

You might lose a little low end torque if you swap out the intake manifold. Seeing that you tow often, it may not be worth it to change from stock. It may perfrom better in the higher RPM ranges like 6,000+ but how often to you drive around with your tach. pegged?. Might want to think about that swap before spending the $.

[Chris]

Now the manifold with long runners made for trucks could cause me to lose torque?

 

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[SnakeEyeSS]

Hmm. I don't think the RT does(as its truck based), just the car based LS- manifolds....

 

 

Maybe he has something/ link to back it up??

[Chris]

I'm just curious. I don't want to cause power loss

 

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[SnakeEyeSS]

FYI the 90 mm ls7 tb bolts to the LSXRT and costs half of what the FAST 92mm tb does if I remember correctly.

[Chris]

For that my worry is electrical. Because I have a Gen III and the ls7 is Gen IV

 

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[BlackZ71Silverado]

Hmm. I don't think the RT does(as its truck based), just the car based LS- manifolds....

 

 

Maybe he has something/ link to back it up??

 

 

I was referring to the I guess you can say car based ones. Should have made that a little more clear in my post....sorry about that.