Cadillac Owners Forum banner

Newbie Question - Upper Pulley, Lower Pulley or Both? A Bit Confused

27K views 24 replies 9 participants last post by  simplec6 
#1 ·
Gents,

Quick question from a newb; I notice some of you do a lower pulley mod, some do an upper pulley mod and some do both. I do understand that these modifications increase S/C boost but could somebody explain which I should do when I get my V?

I have searched on this specific question but there seems to be two camps here specific to pulley mods (upper vs. lower).

Perhaps when in doubt, do both! :)

Thanks in advance for the guidance/advice.

Alex
 
#3 ·
Good questions, here are my goals:

1) I simply want to maximize (safe) Horsepower through modifying boost levels
2) All of this will be done by a professional shop, not by me
3) No real budget issues, assuming labor is similar for both upper & lower pulley

What I'm asking for is if there's a difference/benefit by going with Lower/Upper only or with both.

Thanks.

Alex
 
#4 ·
Lower pulley requires more labor, and more cost. The benefit isn't really that great unless you are looking to maximize the effort with at least headers, or cam, or heads, or a combination of the three. The lower pulley requires a new damper, and the labor is much higher (generally) to R&R that piece than the upper pulley.

Since you have to remove the snout for the upper pulley, a lot of guys also have this ported, which seems to be worth another 10-20 hp or so.

Personally, I don't like the 2.35" pulley, but others have used it successfully. As you get smaller in the upper pulley, the chances of belt slip are greater. If you want to stay safe with this regard, get a 2.5".
Additional mods I'd suggest are an upgraded heat exchanger, maybe a larger tank for the heat exchanger (no power gains, but the ability to stay in boost longer is nice to have), a CAI, and, of course, a re-tune.

Now, when you go to 2.5" upper, you may need to get larger injectors. Otherwise, you can get the 2.85" and know you won't need injectors, but that there is more power to be had.

For reference, Ben (good guy, no affiliation) at Weapon X has put together a very nice chart of information on pulley, belts, etc. I try to keep my blower below 23K rpm, but 24K is probably safe. I'm more conservative, as it's my daily driver, and not needed to race every car I see.

http://weaponxmotorsports.myshopify.com/blogs/news/6826132-lsa-available-pulley-combos-and-supporting-mods-needed

I hope this helps you a bit.
 
#8 ·
You can also modify the stock airbox and use an LPE intake tube if you want to look relatively stock and have perfect (stock) MAF scaling.

A lot of folks do a 160 stat, stock airbox modded with LPE tube, 2.5 upper pulley and tune. With the adjusted fan settings and 160 stat the stock HX is quite effective unless you're into road racing/lapping.

When my warranty is up I'll probably go the above route.

Cheers
Chris
 
#10 ·
You can also modify the stock airbox and use an LPE intake tube if you want to look relatively stock and have perfect (stock) MAF scaling.

A lot of folks do a 160 stat, stock airbox modded with LPE tube, 2.5 upper pulley and tune. With the adjusted fan settings and 160 stat the stock HX is quite effective unless you're into road racing/lapping.

When my warranty is up I'll probably go the above route.

Cheers
Chris
I kept the stock airbox and LPE intake tube. With Kooks headers, 10% OD HB pulley and a mild tune, I gained about 70hp. Ran it, autocrossed it, tracked it for over 3 years and no issues. Was perfect...
 
#9 ·
According to Sticky who posts mods and 1/4 for us on this forum... the above mod is an increase of 90 whp. Not sure where you got your numbers. 50-60 is a bit low unless you are talking a 2.85 or 2.55 upper. The upper size very. I went with the 2.5 cause anything smaller and I would need injectors and other supporting mods that I was not ready for.
 
#13 ·
"I don't have to prove or do anything"....what kind of response is that. Do your own research and stop relying on other peoples due diligence. I have in fact "gone all the way" with my mods so I have some experience with a build. I started with a 2.55, cai, and tune prior to full-blown mod. It was dynoed on a Mustang and DJ...100whp was not found. Now if you add a lower, injectors, and headers to increase boost, then you're getting warmer. "Unless you're saying Sticky is a lier" I don't know who sticky is but I'm sure he has talent - don't put words in my mouth jackass and stop being so hostile as you truly are a Caveman. Go ahead and put a 2.55, cai, and tune and get 100whp - mathematical masturbation at its best. haha
 
#14 ·
I don't see anything hostle in my words sir or mam. I apologize if you feel so. Maybe you should go back and read both our statements and see who is really being hostle or trying to pick an argument. Your statements are also off. I said 90 hp which means we are only differing by 30. I said 2.5 not 2.55. This may be the difference. It doesn't take much with the upper. I here there is a 2.35 now that produces the same as a 10.5 lower. Pick a fight with someone else. And god bless.
 
#17 ·
I agree with Caveman, he doesn't have to prove anything. He was just at first offering his own personal findings from this forum's reputible source, which he didn't have to, but he did for the OP's benefit. Then rayjoedef chimes in with a comment disagreeing with the addition of 100rwhp. good, he's entitled to his opinion even he's a nanny. I'm pretty sure 90whp+ is possible if all the OP wants to do is maximize power through increased boost. Dual pulleys? He'll get hte 90 with a tune, now would it be completely impossible that he would get an aftermarket air intake? more than likely...but maybe he'll tell us for sure. when increasing the boost it's a good idea to introduce some better cooling mods to the system. an air intake is an excellent first step. but if you live in a warm climate year round, you might need to figure out another solution.
 
#21 · (Edited)
Hugh...thanks for the recap but I believe Caveman and I are good. The question inherently asked 100hp gain from a upper, cai, and tune. Nobody mentioned cooling until later in the thread. I may have been a bit aggressive with Caveman but my frustration lies with many claims of high hp with little work. Granted, a lot of cheap hp can be made early in the build but to increase hp by 90-100 at the wheels takes a little more imagination. If you're going to insult me, make sure you re-read what you write for greater impact. You can put your superman cape back in the closet, no saving needed here.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top