To start, there was/is two batches of soft & hard springs for the UNOS

The early soft spring maxed out at 19-20lbs.

The later soft spring maxed out at 24-25lbs.

Since the early soft spring barly made stock evo boost most used the early hard spring.

Now, since the later soft spring had a range that includes 21-23LB, what most people boost on pump gas, people with the later spring set would usually use the soft spring and call it a day.

Some people with the later spring set, would install the later hard spring, for various reasons. They would see boost levels of 24+lbs at the lowest setting. They would fear overboost, make a thread, people would tell about the different batches and they would use the later soft spring and call it a day.

With the later soft spring though, some would see a large taper, more so on a IX, with some IXs taper to 15lbs. (myself included). I know everything about taper and that it will be there, to some extent, no mater what, but 15lbs is too much.

So after putting in the later hard spring to see if I could get rid of taper, seeing boost levels of 24+lbs at the lowest setting, I started going though some past threads. I found this post..

So I took out the hard spring, compressed it a bunch of times with my fingers, probably a 100 or more. Then reinstalled.

IT WORKED PERFECTLY....

At the lowest setting with the later hard spring (broken in), boost 19-20lbs. So tuned it up a little to my normal settings, and presto, a lot less taper. I have not datalogged it on my MAP sensor yet, but can deffinantly see less taper of my gauge then there was previously.


SUMMARY - If you have a later FORGE UNOS MBC on a IX and are experiancing, which you believe to be too much tapering, try the later hard spring. Just make sure to break it in.

DISCLAIMER - If this doesnt work for you, its not my fault. If you over boost and blow your motor, not my fault.

Also, before someone says try it in higher gears, I tested it in 3rd & 4th gear.

 

Quick question, at first you said the hard spring will not boost below 24psi. Since broken in it will in fact go down to 20-21 what most people run on pump, is that correct. Also you said you tapered down to 15psi before, what RPM was that and what did it taper too after the hard spring install. Nice post!

 

That is correct.

I was taper to 15lbs by 7000RPMS, logged via MAP sensor.

I havent logged the hard spring with the MAP sensor yet, so I dont have any numbers yet, but like I said, looking at the gauge, I see less taper and I know that it will show in the logs. I'm guessing I'm probably tapering to about 17lbs now. Ill have logs soon.

 

you could have also cut a very little piece off of the hard spring to do the same thing...

 

Exactly why I will NOT go with the forge now (which I was planning on), and going with the Hallman Pro.

 

I had the UNOS on when i tuned my car and we replaced it with the Dejon Tools MBC and it picked up another 12 HP. It doesn't really have to do with tapering but it's funny that everyone regards it as the best when the ghetto looking dejon one is better.

 

You couldnt do that. The end of the spring is made so it sits on the nipple correctly.

Word. I think that the FORGE is better, but also recommend Hallman

That one story doesnt make dejon better. First you would have to know why the Dejon made more power. Was the UNOS spiking crazy, there fore making knock?? Was the UNOS tapering too much?? These are some of the only reasons one MBC would be better then another. If it was the taper, maybe you should have looked into fixing it before replacing it.

Least you made 12Hp more

 

Thats some good info!

 

How would the forge be better?

 

This is good stuff. My stiff spring kept getting stuck and I was left with like 15-17psi... soft spring tapers too much... now I can't find the stiff spring to compress it manually to give it another whirl

 

Does the Hallman pro have the same problem as the Forge?

 

I came from a hallman.. had it for almost 3 years and never had a problem... not really sure why I switched other than wanting a change under the hood.

 

Ohh ok, since you've had both which would you recommend? I'm asking cause I'm ordering mine next week .

 

I really couldn't say... Both have different advantages.. plus I still need to find/buy another stiff spring so I can try what's mentioned above.

Besides the random sticking with the stiff spring (which is unacceptable) Forge is nice.. I like how it looks and how you can mount it... I also like how it "clicks" when you turn the knob.

The hallman never had any sticking problems.. or any problem for that matter. I didn't like how it mounted.. the mounting bracket would get very hot allowing the mbc to move around a little

 

Alright, thanks, I think I just may go with the hallman since my friend has one in his Evo also, and never had problems.