Bored out throttle body

[jamespwsullivan]

There used to be at least one forum member who bored out throttle bodies (Mean Lemons IIR) and I'm wondering if anyone is still doing it or knows of a good resource if I want to have it done.  I know there is a lot of discussion of upgrading to a HO head but my situation is that the entire 4.0 is from a 2003 TJ but I am still running Renix.  There may or may not be an advantage to a larger throttle body so I am just looking into my options.

Thanks

[Limeyjeeper]

Leigh performance machine still does them. www.strokedjeep.com

[jamespwsullivan]

Thanks!  I just now found that site from this thread.  There seems to be some differences of opinion when it comes to later 4.0s based on my experience in the wrangler TJ forum, but that doesn't compare apples to apples exactly.  I'm going to measure mine next week.  I suspect I may have an early model (Renix) intake manifold with the Renix throttle body on what I know is a 2003 4.0 with the year-appropriate head.  That seems like a mismatch to me but it's hard to be sure without more info.

 

[75sv1]

I have bored my own TBs. From other post Leighs does good work on them. The TB pictured above is  RENIX. RENIX TBs can be bored to 58mm(straight through) and sometimes to 60mm. HO TBs can be bored to 60mm (straight through) and to 62 mm. I have noticed a bit better performance on inclines with a 60mm TB on a stock motor, with a 2.5 cat back and a header. Also, with the 99+ intake. Not a bunch, but enough where I am not down shifting. 

[Whitaker717]

On 8/11/2024 at 6:38 PM, Limeyjeeper said:

Leigh performance machine still does them. www.strokedjeep.com

I second this. Jeff just did mine the middle of July. I have the 4.0 Auto. He noted it to 60mm. I don’t notice a huge difference, but I do notice a difference. It’s an upgrade I am glad I did!

[ghetdjc320]

The taper in the throttle body helps improve velocity and contributes to that low end torque. Jeff does a great job boring TB’s and I’ve ran several from him but the torque band always shifted higher. Painless performance made a “perfect” throttle body that maintained a nice taper but opened up the bore further. With supporting mods, it’s a nice setup. 

[Crash]

I have run 3 of the LP bored renix TBs on a few vehicles. Worked well. I only have one heep left, which is my MJ 4.0 that has bored TB on it. 

 

There are a few options to still utilize your renix setup. 

1. Use renix intake on XX 4.0 block, 

2. Run 91-up intake ( 99+ preferred for better flow), with late model TB and Hesco TPS adapter.

3. Make an adapter to fit the renix TB on late model manifold. 

 

Several years ago I was working on a CADD drawing of an adapter for the TB. 

Never got around to finishing it. Or attempting to build one. 

 

[Spinnakerblue89]

16 hours ago, ghetdjc320 said:

The taper in the throttle body helps improve velocity and contributes to that low end torque. Jeff does a great job boring TB’s and I’ve ran several from him but the torque band always shifted higher. Painless performance made a “perfect” throttle body that maintained a nice taper but opened up the bore further. With supporting mods, it’s a nice setup. 

And what supporting mods might those be? I imagine a better exhaust system form the headers down matter a lot.

[ghetdjc320]

5 hours ago, Spinnakerblue89 said:

And what supporting mods might those be? I imagine a better exhaust system form the headers down matter a lot.

     Higher comp ratio and an updated head design such as the Edelbrock in combination with cam, intake exhaust and TB’s are good places to start. Of course a stroker kit can also add some displacement. There is a decent amount to be gained on a 4000cc engine though. It’s just been my observation that certain TB and cam choices on a stock 4.0 can improve your overall HP numbers but do little to improve torque and/or move it too high in the RPM range. 
 

But ultimately, a good running stockish 4.0 benefits greatly from proper gearing. It’s by far the best bang for the buck as the gears are you’re torque multiplier. 

[75sv1]

The 2003 Head is a bit restrictive in the exhaust ports. I plan to try my hand at a TUPY head. I've done 3 Jeep heads. A '95 and two '99's. From other sources, porting a head can add 15hp to 20 hp. Also, the valve spring might or should be upgraded. The 'max' lift on stock springs is .450. I also, used a 30 degree seat on the intake. I went with 37 degree intake on an LS head. You have to watch the diameter of the exhaust valve. Max is 1.57. Newcomer does use 1.6 valves though. Also, the HO valve springs have a bit higher spring pressure. I used Melling. 

[jamespwsullivan]

On 8/15/2024 at 3:15 AM, Crash said:

I have run 3 of the LP bored renix TBs on a few vehicles. Worked well. I only have one heep left, which is my MJ 4.0 that has bored TB on it. 

 

There are a few options to still utilize your renix setup. 

1. Use renix intake on XX 4.0 block, 

2. Run 91-up intake ( 99+ preferred for better flow), with late model TB and Hesco TPS adapter.

3. Make an adapter to fit the renix TB on late model manifold. 

 

Several years ago I was working on a CADD drawing of an adapter for the TB. 

Never got around to finishing it. Or attempting to build one. 

************************

Thanks for the info.  I think going for option 2 makes the most sense but Hesco isn't guaranteeing shipping until November. I'm looking at other vendor options and am happy for any suggestions.

 

[ghetdjc320]

7 hours ago, jamespwsullivan said:

 

The one from boosted technologies seems nice and there are also a couple of diy write ups involving spacers. 

[jamespwsullivan]

ghetdjc320 - I agree about the boosted technologies option. Looking into it a little more.