Throttle Body Spacers?

[cruiser54]

Lots of minor gains that add up to noticeable gain. 

 

Did I ever post this here?

 

HO myth buster

 

 

Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference. 

 

HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had 58 mm throttle body versus a 52 mm throttle body on a Renix and also had a better design header. See where I'm going with this?

 

The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold.

 

Put a 60mm TB from www.strokedjeep.com on your present head, eliminate the "crush" in your headpipe with proper re-routing, and go for it. 

 

HO stands for Highly Overrated.

__________________

[outlaw star]

Great to see so many intelligent people here that you can have an a real conversation with unlike the normal crowd I deal with. "Yo, Wut it take 2 fit dem' 22's under my ride?" Lol

[johnj92131]

After I posted my "why didn't the factory do it" comment, I remembered some NASCAR guys used "spacers" under the throttle body after the size of the throttle body was limited.  Seem to recall it was to smooth out turbulence in the intake air stream.  Then I remembered some spacers used under carbs were there to insulate the fuel from the hot engine manifold some times from the factory.  So sometimes spacers do have a valid use.  Don has posted some good observations and it will be nice to see another dyno run on his engine (after the roller rocker conversion?).

 

Cruiser54, where did the Renix 4.0 put out 182 hp? 1990 what?  Do know the Renix era 4.0 had better low end torque and a knock sensor.  The real issue with the Renix is the limited electronics in the controller, right (and age)?  The knock sensor and high altitude CPS seem to work together very nicely. The cam was also tuned for more low end torque compared to the H.O. cam.

[cruiser54]

After I posted my "why didn't the factory do it" comment, I remembered some NASCAR guys used "spacers" under the throttle body after the size of the throttle body was limited.  Seem to recall it was to smooth out turbulence in the intake air stream.  Then I remembered some spacers used under carbs were there to insulate the fuel from the hot engine manifold some times from the factory.  So sometimes spacers do have a valid use.  Don has posted some good observations and it will be nice to see another dyno run on his engine (after the roller rocker conversion?).

 

Cruiser54, where did the Renix 4.0 put out 182 hp? 1990 what?  Do know the Renix era 4.0 had better low end torque and a knock sensor.  The real issue with the Renix is the limited electronics in the controller, right (and age)?  The knock sensor and high altitude CPS seem to work together very nicely. The cam was also tuned for more low end torque compared to the H.O. cam.

Actually, the HO had the same cam as Renix through about 95.

 

182 HP was in 89 and 90.

 

87 was 173, 88 was 177.

 

Put an 89 or 90 ECU in your 87 or 88 and feel the difference!!

 

Torque was about the same and horsepower in the HO was only in the higher RPM ranges.

 

I'm gonna run a stroker on a Renix ECU. Ain't skeered. It's not "limited", just basic.

[conker]

Feels like a dumb question, would an 89/90 Renix ECU just be a plug and play type deal?

[dybamx]

little bit of a hijack here, but what is "crush in the head pipe" ? I imagine some sort of exhaust defect, but don't really know

[88whitemanche]

Great to see so many intelligent people here that you can have an a real conversation with unlike the normal crowd I deal with. "Yo, Wut it take 2 fit dem' 22's under my ride?" Lol

Lol I know what you mean....

In both my jeeps guys at work guys keep saying your truck would look good with some 30" rims and low pros

 

Sorry to thread hijack

[Incommando]

I know jeep chose to call them "H.O.'s" despite only a modest power increase but they should have called them "GFEN's" for Goodbye French Engineering Nightmares. My '91 OBD ( see? no H.O. reference) is infinitely easier to diagnose and deal with then my '88 RENIX was... And I daresay that every dollar spent upgrading a RENIX would provide a gain on the OBD as well. The 99-up manifold, bigger throttle body, improved exhaust, etc..., are all things that would improve a 91/92 and probably as much as they do a RENIX. If you wanna feel the difference switch from an '88 to a '91 like I did...the increase in HP from '90-'91 was greater than the '88-89 difference  :brows:

[cruiser54]

Feels like a dumb question, would an 89/90 Renix ECU just be a plug and play type deal?

Absolutely. You can use the ECU from an 89 to 90 auto trans equipped MJ or XJ in either an auto or stick vehicle. The ECU from a stick trans XJ or MJ is best used only in a vehicle equipped with a stick.

[cruiser54]

little bit of a hijack here, but what is "crush in the head pipe" ? I imagine some sort of exhaust defect, but don't really know

It's a factory added "crush" disguised as clearance for the front exhaust pipe to driveshaft clearance. The crush can be eliminated as long as the pipe is routed differently. I have my local muffler shop fab them up on the vehicle. The "crush" was put there to restrict the exhaust flow so the catalytic converter would start working sooner. 

[cruiser54]

I know jeep chose to call them "H.O.'s" despite only a modest power increase but they should have called them "GFEN's" for Goodbye French Engineering Nightmares. My '91 OBD ( see? no H.O. reference) is infinitely easier to diagnose and deal with then my '88 RENIX was... And I daresay that every dollar spent upgrading a RENIX would provide a gain on the OBD as well. The 99-up manifold, bigger throttle body, improved exhaust, etc..., are all things that would improve a 91/92 and probably as much as they do a RENIX. If you wanna feel the difference switch from an '88 to a '91 like I did...the increase in HP from '90-'91 was greater than the '88-89 difference  :brows:

But if you've already got a Renix....and have the tech support available here, I say go for it.

[dybamx]

 

little bit of a hijack here, but what is "crush in the head pipe" ? I imagine some sort of exhaust defect, but don't really know

It's a factory added "crush" disguised as clearance for the front exhaust pipe to driveshaft clearance. The crush can be eliminated as long as the pipe is routed differently. I have my local muffler shop fab them up on the vehicle. The "crush" was put there to restrict the exhaust flow so the catalytic converter would start working sooner. 

 

thanks, I will look into it when I do my engine swap