Maggie Pulley Size with Stock Motor + LT Headers?

[Z71456]

I just recently bought some ARH long tube headers and had them installed by the shop that did my Maggie install and tuning. They tuned it and it runs great, but I'm just wondering if the pulley is too small resulting in too much boost? The pulley is a 3.2 and so far I've seen 11psi on my gauge. From everything that I know and have read, this seems pretty high. They told me after they tuned it that they weren't able to get much timing out. I think 6 degrees and that's it.

The car runs and sounds great, but I am just curious if I'm asking for trouble here? I recently installed an Aeroforce Interceptor gauge and one of the parameters I have set is "Knock Retard". I noticed today when I put my foot in it, not even all the way, that it starts showing that it's retarding the timing. Is that normal? I know nothing about actual tuning and how the computer works that way so pardon my ignorance if this is something normal. I'm just wondering if I would get more reliability and possibly better performance by going to a 3.4 pulley and getting more timing out of it during tuning?

Any help or opinions would be greatly appreciated. The shop I used is incredibly reputable and I feel confident he wouldn't do something that would be detrimental to my engine, but I'd just like to get some feedback from those that have similar set ups and experience.

Thanks!
-Chris

[UNRIVALED SS]

First of all, I`m no expert either. I will share with you what the guys at MTI told me, and what little knowledge I have after running my own car for about a year now. I asked about reliability and boost numbers. They told me that they had no problem in testing untill boost got to 11 PSI. They said that at that point they broke a piston. I`m sure they were thrashing the thing. Anyway, I know that you are making a lot of power and I didn`t see a aftermarket cam listed in what you`re running. I`m making 533 hp and I`m running a fairly aggressive cam package and the 3.6" pulley with 7 psi of boost. They said I could run the balls of it and I wouldn`t have a problem, and I have. No problem so far. I am not the knowledgeable expert here at all but, I saw that no one had responded yet and thought I would pass on what little I do know. Good luck with it, and I`m sure the guys on here will have so real nuts and bolts numbers for you to crunch pretty quick.

[alfie43]

Originally Posted by Z71456

I just recently bought some ARH long tube headers and had them installed by the shop that did my Maggie install and tuning. They tuned it and it runs great, but I'm just wondering if the pulley is too small resulting in too much boost? The pulley is a 3.2 and so far I've seen 11psi on my gauge. From everything that I know and have read, this seems pretty high. They told me after they tuned it that they weren't able to get much timing out. I think 6 degrees and that's it.

The car runs and sounds great, but I am just curious if I'm asking for trouble here? I recently installed an Aeroforce Interceptor gauge and one of the parameters I have set is "Knock Retard". I noticed today when I put my foot in it, not even all the way, that it starts showing that it's retarding the timing. Is that normal? I know nothing about actual tuning and how the computer works that way so pardon my ignorance if this is something normal. I'm just wondering if I would get more reliability and possibly better performance by going to a 3.4 pulley and getting more timing out of it during tuning?

Any help or opinions would be greatly appreciated. The shop I used is incredibly reputable and I feel confident he wouldn't do something that would be detrimental to my engine, but I'd just like to get some feedback from those that have similar set ups and experience.

Thanks!
-Chris

Chris,
I have an LS3 with 1-7/8" headers, high flo-cats and a CAI. My tuner and Magnasun recommended that I drop down one size on the pulley to compensate for the slight loss in boost from the headers. As you know the kit includes a 3.8" pulley, so we installed a 3.6" and that provided around 7lbs boost. I asked for a safe and conservative tune and in doing so, the car pulled 561 RWHP. I should add that I do not have any fuel delivery upgrade (BAP).

I am hesitant to comment on your specific setup because I am not an expert; I only have an opinion and from what I have seen and read, I would be a little leery with 11 lbs of boost. You are going to get a lot of opinions here and I don't doubt that some of it will be conflicting, albeit well meaning. There are some knowledgeable tuners that lurk around this forum, i.e., Ted Jannetty. You would be wise heed their advice and ignore the rest.
Alfie

[GTAHVIT]

3.2 is way too much boost without a BAP or dual pump.

My guess is it's running out of fuel and casuing it to detonate, and that's the knock/timing pull you you are seeing.

On your setup I'd not go beyond a 3.6 until you can meet the fuel demands.

I don't know if your aeroforce guage can display fuel pressure but I'd make sure you aren't seeing a drop in fuel pressure first.

I'm thinking you are playing with fire if you are running the stock fuel system.

[Z71456]

Thank you all for your replies. I really appreciate it. I honestly think the only reason that the shop put that small of a pulley on was because maybe that was all they had. I don't know, but that was the impression I got at the time.

3.2 is way too much boost without a BAP or dual pump.

My guess is it's running out of fuel and casuing it to detonate, and that's the knock/timing pull you you are seeing.

On your setup I'd not go beyond a 3.6 until you can meet the fuel demands.

I don't know if your aeroforce guage can display fuel pressure but I'd make sure you aren't seeing a drop in fuel pressure first.

I'm thinking you are playing with fire if you are running the stock fuel system.

I do have fuel pressure and the pressure does go down at WOT of course, but not too low at all. When the tuning was done, the car was not running out of fuel or at a dangerous level. They spent a few hours on tuning and absolutely made sure of that. The fuel pump is however at it's max and I was planning on doing a dual pump, but I wanted to address this issue first. Since the engine isn't running out of fuel, then that isn't my problem right now, nor do I have any problems, YET. I know the car should have a fuel system upgrade and I plan on it, but I just wanted to get some opinions from tuners and others with maggie/header combo on pulley size.

Thank you. I'm thinking that I'm already going to email the shop and get something done about this.

[GTAHVIT]

Originally Posted by Z71456

Thank you all for your replies. I really appreciate it. I honestly think the only reason that the shop put that small of a pulley on was because maybe that was all they had. I don't know, but that was the impression I got at the time.



I do have fuel pressure and the pressure does go down at WOT of course, but not too low at all. When the tuning was done, the car was not running out of fuel or at a dangerous level. They spent a few hours on tuning and absolutely made sure of that. The fuel pump is however at it's max and I was planning on doing a dual pump, but I wanted to address this issue first. Since the engine isn't running out of fuel, then that isn't my problem right now, nor do I have any problems, YET. I know the car should have a fuel system upgrade and I plan on it, but I just wanted to get some opinions from tuners and others with maggie/header combo on pulley size.

Thank you. I'm thinking that I'm already going to email the shop and get something done about this.

Cool!

I'm sure if they are a good shop they'll get you sorted out.

I'd just be careful of going WOT in 5th and 6th near redline... obviously you'll be going real fast at that point so I can't imagine you do that very often anyway.

And I'd make sure not to go WOT at very low RMP < 3k when it too high of a gear. always downshift in other words.


Other than that I'm guessing you are good to go. The only other problem may be your exhaust hitting the tunnel brace.

I had this happen to mine and it was triggering the knock sensor and pulling like 14 degrees of timing... so check to make sure there are no exhaust rattles.

[Darth_Emma]

I have LT headers, an MSD BAP, and the 3.6" pulley. It makes between 7 and 8 lbs of boost (depending on rpm). My car is an L99 and it makes right at 500 rwhp.

I am adding a cam and stall in a couple of weeks. My biggest concern is fuel delivery. The tuner will evaluate the duty cycles of the injectors and how hard the BAP is working at that point and advise me as to whether I need to upgrade my injectors and go with a dual fuel pump system.

My shop knows my top priorities are safety and reliability. Getting enough fuel to the motor is essential in a supercharged car.

[J Webb]

Originally Posted by Z71456

Thank you all for your replies. I really appreciate it. I honestly think the only reason that the shop put that small of a pulley on was because maybe that was all they had. I don't know, but that was the impression I got at the time.



I do have fuel pressure and the pressure does go down at WOT of course, but not too low at all. When the tuning was done, the car was not running out of fuel or at a dangerous level. They spent a few hours on tuning and absolutely made sure of that. The fuel pump is however at it's max and I was planning on doing a dual pump, but I wanted to address this issue first. Since the engine isn't running out of fuel, then that isn't my problem right now, nor do I have any problems, YET. I know the car should have a fuel system upgrade and I plan on it, but I just wanted to get some opinions from tuners and others with maggie/header combo on pulley size.

Thank you. I'm thinking that I'm already going to email the shop and get something done about this.

Sometimes you can trade timing for boost. Lowering cylinder pressures but keeping same power output is always a good thing for longevity. However, I would always choose the "professionals" opinion over a forum opinion. Asking questions is always a good thing. As a shop owner it can be very frustrating when my customers question my opinion on something I'm an expert on because of something they read on a forum. Every situation is different and the trick is keeping a perfect balance so that everything works in perfect harmony. Thats why you need a good shop, and an even better experienced, expert tuner. Hope this helps and good luck!

[GTAHVIT]

Originally Posted by J Webb

Sometimes you can trade timing for boost. Lowering cylinder pressures but keeping same power output is always a good thing for longevity. However, I would always choose the "professionals" opinion over a forum opinion. Asking questions is always a good thing. As a shop owner it can be very frustrating when my customers question my opinion on something I'm an expert on because of something they read on a forum. Every situation is different and the trick is keeping a perfect balance so that everything works in perfect harmony. Thats why you need a good shop, and an even better experienced, expert tuner. Hope this helps and good luck!

Yup... I struggle with this sometimes since I like to understand why and how it all works. But in the end I did my homework on the shop so I have to trust him to take care of me.

Go with the experts. Forums are good for giving you things to consider but the professionals are the ones who are gonna make it right.

[Z71456]

I totally agree 100%. I'm not a tuner and I did my homework as well before deciding on which shop for my supercharger and the header install and tune. The shop I chose is a very reputable shop and machine shop with decades of experience. It's just that when I arrived for the header install, he had forgotten that I had a Magnacharger (that they installed/tuned) and I think his pulley choices were limited because he hadn't anticipated doing a pulley change. That is the impression that I got when I was there and it seemed like they made it work with what they had.

I wouldn't normally question a tuner, especially someone with that many years of experience. However, when you get that gut feeling and you're consistently seeing 11lbs. of boost, it made me question it enough to at least ask opinions on here. There are a lot of reputable tuners on here as well as individuals with identical setups as mine. I'm not going to base any concrete decisions off of anything that any one person says on here, but I will collectively take the feedback and opinions and approach my shop or another to reevaluate what was done on my car.

I drive my car fairly easy most of the time, but for those times that I drive it really hard, I don't want to have my motor grenade.

[victoryred1ss]

I think your definately playing with fire using the 3.2 pulley. I would switch to the 3.4 or 3.6 until you get your fuel system upgraded.

[Darth_Emma]

Not to knock any tuner's knowledge, but I think some shops just assume you want all the hp they can squeeze out of it with your current configuration. "More bang for your buck" so to speak. It is your car and it can't hurt to ask questions about it and tell them safety and reliability are your top priorities.

I know my shop treats my car differently than some other customers' cars because they know I'm not just after the fastest time slip.

[Z71456]

Thanks guys!

I spoke with the shop this morning and we're getting another pulley and retuning in a few weeks. Probably 3.4 to bring me to about 8psi, which is what it was at before the headers. I already ordered a dual-pump through Stillen and am having them install it. It should arrive in a few weeks and once it is I'm going back to the other shop to have the pulley installed and the car re-tuned.

Thank you everyone for your valuable input and sharing with me your setups and experiences. I really appreciate it.

[Z71456]

Darth_Emma Not to knock any tuner's knowledge, but I think some shops just assume you want all the hp they can squeeze out of it with your current configuration. "More bang for your buck" so to speak. It is your car and it can't hurt to ask questions about it and tell them safety and reliability are your top priorities.

I know my shop treats my car differently than some other customers' cars because they know I'm not just after the fastest time slip.

I couldn't agree more with that statement. I think at the time they were just trying to get as much out of it with what they had without asking me what my goals were or what my intentions were with all that HP.