Supercharger smaller pulley?

[1973Guppie]

I am considering replacing the stock trd kit pulley with this one from pulley boys:

http://www.pulleyboys.com/store/product.php?productid=51&cat=90&page=1

curious as to what ill effects if any this might cause to my setup?

I am planning to run an air to air intercooler with hood scoop, aluminum 3 core radiator, landtank clutch fan, hood vents, etc. I also plan to have the top end rebuilt, valve job and new HG.

Thanks,

Noah

 

[wearsabrowncoat]

Added heat and possible early detonation. That being said, the people running similar setups have not run into those problems. I don't have any reason to believe you would toss the old pulley so you could easily swap it back if you had problems. I'm headed the same direction and I considered swapping pulleys back and forth for summer and winter conditions. Of course once I had the added power that bigger pulley might never see the light of day again.

 

[1973Guppie]

bump, would love to hear from others whom have switched to the 2.8 size pulley and what they have seen? thanks!

Noah

 

[ClankBang]

I have not switched pulleys nor do I have a ton of experience with gas/forced induction.
I do have experience with turbo diesels though.
I think some knowledge should transfer.

For the basics more air means need for more fuel so at some point you will run into issues with the stock fuel system no being able to keep up (i don't think you will run into this with a S/C but probably with the turbo).
I think the ECU should adapt because you are only going up form 5psi to maybe 7-8 psi. (turbos run in the 15-16 I think)
Some fine tuning with spark plugs and timing will probably be in order.

The thing I would be most concerned with is heat; I'm not sure if the location of inter-cooler is the best.
When you are moving it would be fine but if you off-road where you are sitting still or moving slowly for hours I would worry that the cooler would get heat soaked and the effects would be opposite of what is desired.

I know guys have done it but I haven't read any follow ups on how it preforms.

Again I am an armature and still trying to get my S/C working 100%.

 

[1973Guppie]

well, I spoke with the guy at pulley boys and he was a real nice dude. Basically he said that the computer should compensate for the smaller size fine. My main concern was really screwing stuff up right off the bat by purchasing and running a smaller pulley. I figure if it does not work out I can remove and replace with the trd pulley. I am going to order one today.

Noah

 

[S.CarolinaFZJ80]

I have not switched pulleys nor do I have a ton of experience with gas/forced induction.
I do have experience with turbo diesels though.
I think some knowledge should transfer.

For the basics more air means need for more fuel so at some point you will run into issues with the stock fuel system no being able to keep up (i don't think you will run into this with a S/C but probably with the turbo).
I think the ECU should adapt because you are only going up form 5psi to maybe 7-8 psi. (turbos run in the 15-16 I think)
Some fine tuning with spark plugs and timing will probably be in order.

The thing I would be most concerned with is heat; I'm not sure if the location of inter-cooler is the best.
When you are moving it would be fine but if you off-road where you are sitting still or moving slowly for hours I would worry that the cooler would get heat soaked and the effects would be opposite of what is desired.

I know guys have done it but I haven't read any follow ups on how it preforms.

Again I am an armature and still trying to get my S/C working 100%.

With my TRD SC with stock pulley, I could consistently get 6psi of boost as measured by my ISSPRO manifold pressure gauge.

After installing Nicks top mount intercooler with TRD pulley, I can only get 5.5 to 5.75psi. This intercooler is well designed had has minimal resistance to the airflow. I was expecting to lose about 1psi after installing it but was pleasantly surprised with the results.

As far as the heat goes, with a good cooling system, vents, etc... will definitely help matters. When crawling, I doubt heat soak will be that much of an issue. Since the SC won't be boosting and thus won't be compressing and heating up the intake air. I have never got into boost while wheeling and now with a hood scoop, there is even more venting capacity.

I am running the stock MR2 Denso plugs that are 1 heat range cooler than the LC plugs. I don't recall the part number but Beno and CDan have posted the #'s on here many times. That could help with any potential detonation.

 

[1FZj80]

I think Cdan has run the smaller pulley(s). You might call/pm him for info. I don't think he had any problems, but he is running the meth injection on a '94.

 

[Atoyot1031]

I've been running a 2.8" since installing my air to air intercooler setup without issue. I live at 8,000' and drive the highest mountain passes while pulling either a camper or boat on 37s. I know of folks using the stock fuel management running 10.5psi of boost (turbo) without issue. I do not have my boost gauge installed yet, so I do not know what boost I am at with the intercooler & 2.8" pulley. Once I know my boost, I will likely be installing a yet smaller pulley to push my boost near 10psi.

The only issue I see is that once I put the 2.8" pulley on, the SC belt became very easy to remove. In all of my driving, it has not come off, but if I go smaller than 2.8", I will likely install a larger idler pulley to pickup the slack. My .02
Nick

 

[1973Guppie]

so Nick, it sounds like I don't need to worry about getting another belt with the 2.8 pulley? I doubt I will ever go smaller than that size.

Noah

 

[seattle80series]

I'm considering a smaller pulley myself. Are people using piggyback systems at all to get the correct A/F?

 

[thespecialone]

You'll spin the blower faster obviously but you need to figure out how many additional RPM's the TRD unit can handle. As an example, the stock Heaton on the 03-04 Terminators came with a 3.10 pulley and running a 2.76 was considered the upper limit of safe.

 

[blarsen]

I have had Zero problems with the 2.8 pulley, belt fits great, SC spools up fast now! I live at 4800 ft, I have had it as low as St. George (2800 ft) with no problems (intercooler and premium gas). good luck

 

[bmw635]

I've been running a 2.8" since installing my air to air intercooler setup without issue. I live at 8,000' and drive the highest mountain passes while pulling either a camper or boat on 37s. I know of folks using the stock fuel management running 10.5psi of boost (turbo) without issue. I do not have my boost gauge installed yet, so I do not know what boost I am at with the intercooler & 2.8" pulley. Once I know my boost, I will likely be installing a yet smaller pulley to push my boost near 10psi.

The only issue I see is that once I put the 2.8" pulley on, the SC belt became very easy to remove. In all of my driving, it has not come off, but if I go smaller than 2.8", I will likely install a larger idler pulley to pickup the slack. My .02
Nick

You can get a shorter belt 3-5mm to take up the slack instead of larger pulley. If you guys let me know current pulley's PSI and smaller pulley PSI boost with other mods your plan and I could tell you what else is rec'd.

I built my own SC for the BMW putting out 450 hp so I know a lil about FI.

 

[murf]

I have a 3.0 pulley from pulley boys Im going to install and see if any discernable difference. curious how the approximate 40% increase in boost (5 to 7 lbs of boost) will perform ...?

 

[concretejungle]

I have a 3.0 pulley from pulley boys Im going to install and see if any discernable difference. curious how the approximate 40% increase in boost (5 to 7 lbs of boost) will perform ...?

any follow-up on this old thread? Was thinking about the 3.0 pulley but I do not have an intercooler.

 

[murf]

any follow-up on this old thread? Was thinking about the 3.0 pulley but I do not have an intercooler.

I run it all the time now and feel a slight pick up in throttle response. Not 40% worth though ha...doesn't seem to make a difference in engine temps. Id do it again.

 

[1973Guppie]

I put the 2.8 pulley on without any intercooler etc and did not like how it was running. It just seemed off to me in the throttle range. I decided to go back to the stock pulley. I now have installed a meth system and may put the smaller pulley on in the future to see how it performs. I am also thinking that the 3.0 pulley might be a better fit for all seasons. What I am concerned with is not having to rely on the meth injection to cool the charge if I run out of fluid. The methanol system worked well on a recent trip. We were going through areas where it was over 100 degrees + ambient outside and I could see the intake drops drop during boost on hills. It uses quite a bit of fluid which is another reason I may just stay with the stock pulley size.

 

[concretejungle]

thanks for the reply. With the weather about to turn colder I'm going to make a run at the 3.0 pulley.

 

[Pierce]

Here’s my experience... South Texas 97 degrees or so. No intercooler.
-Refreshed my entire cooling system with all oem stuff in 2017 and topped it off with landtanks blue hub fan clutch.
-With 3.25” pulley no heat issues. Averaged 196 or so degrees water temp. 5 psi. Pretty boring.
-Moved to 2.8 pulley. Average high 8 psi, occasionally 9psi. Cooling system could not keep up. Got up to 230 or so degrees on the highway at 75mph. Power gain was Ok but not worth the heat. It also devoured a set of MR2 spark plugs in about 6k miles. Went back to 3.25 pulley.
-2 weeks ago went to 3.0 pulley. 7psi average high. No cooling issues, still averages 195 degrees. Feels better on the street. Don’t feel like I’m stressing anything. No cooling issues at 75mph.

Going to stay with the 3.0 until @NLXTACY makes us a top notch intercooler.

 

[NLXTACY]

I think it’s time to swap in the 3.0 myself and get meth injection working.

intercoolers have been on my mind