Boost problems - I should be getting more

[azgolfrat]

Hey Guys,
I connected with the manager of a local air strip. After I signed a waiver, I was given the gate code and access to the runway :-)
I've seen 2 planes land on this strip in 9 years - so pretty safe.
A local/rural helicopter will land and take off from time to time for medical transports.
Pretty sweet.
Anyway, long story short, with the car running nicely I got in about 5 WOT runs up to about 105 mph, then had to begin slowing as the strip end was approaching.
BUT, my boost, per the pod gauge, never got over 5 psi.
For these WOT runs I turned off the overdrive and started in 1st gear. I shifted into second at about 5.5Krpm and into drive at about 5.5Krpm
On the last run I removed the air filter (very clear sky no wind) and got the very same result.
In both 1st and 2nd belt squealing could be heard above ~ 3500 rpm.
After the runs, the smell of burning rubber could be detected; not overwhelming, but definite.

With the set up I have, I think that over 5 psi boost should be easily achieved,
The system uses a Vortech Mondo bypass valve which vents ** and there is no rerouting of air back into the supercharger **. I can hear it vent when the throttle closes at high rpm.
I recently put a Motorcraft OEM tensioner on the car, which did stop belt slip when the AC was operated.

So, where is the boost???? I'm not sure a slipping belt accounts for this? (Blazen has prev suggested a different belt, and that is definitely on the list)
Any inputs as to how to get the boost back would be appreciated.
Thanks

[blazen71]

The belt slip is the main reason you're not getting more boost. What is the supercharger pulley diameter. That will give you an idea of where the boost should be. You also need to be sure the supercharger pulley is aligned really good with the other pulleys. If its off you will not have good belt to pulley contact and that can cause slippage.

There's other factors too. Having headers the air flow thru the motor is better so you'll see lower psi than stock manifolds. But that's ok. Your making more power more efficiently with headers.

You have 3.55 diff gears and probably a factory stall torque converter. If you had numerically higher gears and a high stall your engine rpm would ramp up faster as well as the supercharger, pushing air faster and making slightly higher peak boost.

Also, with a centrifugal s/c, the higher you rev them the more peak boost it'll make. You should be easily safe to rev to 6k rpm. That extra 500 rpm makes a difference, if your belt isn't slipping.

Make sure you have a good vacuum line hooked up to your Blow off valve. Technically you should have an independent line ran from the upper intake manifold to the valve. When your motor is under boost, the boost pressure is in that line helping to keep the valve closed.

[justbob]

Everything Blazen said. Plus I would just put it in D and stab it. Redline isn’t the actual redline anyways. At least on occasion.. And yes, I know this from early days with only a Trilogy and thinking the trans was as fast as my hand but RPMs prevail.


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[azgolfrat]

Blazen and JB, thanks. The SC gear is 3.33 6 rib, by Vortech, came with kit.
Can you say what is the math to go from pulley d to lbs of boost?
I will find a route for an independent vacuum line to the BOV...right now it is not independent.
I will get and install the Gates belt we discussed previously.
I'll have to scratch my head on pulley alignment..I think it is good, but I will find a way to verify.
Thanks again guys

[blazen71]

That pulley is too small for a 6-rib, even with the RPM belt you will always get slip. If you are keeping the 6 rib setup, I would recommend a 3.6 pulley and an Innovators West 10% OD harmonic balancer. That would get you about 12psi. In my opinion that would be the easiest way to stop the slip. You will probably have to get a different length belt.

https://innovatorswest.com/product/812-mod-damper/

[blazen71]

For pulley alignment you can use a Dayco or Gates laser alignment tool.

https://www.gates.com/in/en/power-transmission/power-transmission-tools-and-merchandisers/power-transmission-tools.p.7468-000000-000010.v.IN-7468-0023.html?related=true

https://na.daycoaftermarket.com/en/products/tools/installation-tools/dayco-belt-diagnostic-kit/

[azgolfrat]

Blazen, thanks.
I dont understand why the harmonic balancer makes a difference for slip - sorry for the dumb question, but this is new to me at this point. Could you explain?
Thanks

[blazen71]

It indirectly helps with slip. It's a larger diameter balancer so it spins all the pulleys faster by 10%. That way you can use a larger supercharger pulley to get better belt wrap (the larger the pulley the more belt contact you get over the circumference of the pulley). The overdrive balancer will make the 3.6" s/c pulley spin the s/c as if it had a 3.24" pulley.

[blazen71]

To be honest, Chris should not have sold you a s/c kit with a 6-rib 3.33" pulley.

[azgolfrat]

It indirectly helps with slip. It's a larger diameter balancer so it spins all the pulleys faster by 10%. That way you can use a larger supercharger pulley to get better belt wrap (the larger the pulley the more belt contact you get over the circumference of the pulley). The overdrive balancer will make the 3.6" s/c pulley spin the s/c as if it had a 3.24" pulley.

Blazen , thanks.
Well, I do enjoy a challenge [emoji16]
This SC has an oil drain line back into the oil pan that may prevent any larger a balancer being put in place. With the stock balancer there is about 1/2 inch clearance.


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[blazen71]

Remember, if you do this, you will need to do another remote tune with Marty. Updates like this are easy for him. About 3 logs and you should be done.

[justbob]

With stock gears and converter you will get a really good slingshot effect with minimal wait time. Comes on fairly quick and just builds and builds. My car hammered it HARD and still built and built the longer you dared to ride it out and the rear really didn’t like that! It felt like compound boost or how I’d imagine it feeling.

With yours I’d look into 4.10’s and probably not touch the converter or maybe a small upgrade but I’d stay away from anything too aggressive with the boost you plan to make. Your rear will appreciate not getting punched in the face every time you hammer it. That’s just good advice for a long lasting trustworthy street car. Not that I’d do that, but feel I should help steer you right. I don’t mind breaking things, easier to sell myself on upgrades. [emoji16]


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[azgolfrat]

Guys, thanks for all the inputs.
I did make one adjust that seems to have made a change in the right direction. I did a lot of reading on the Vortech Mondo blow off valve I have installed (part # 8D003-010). Then I took it out and popped it opened it to see if all looked ok. It did. I called Vortech and made sure I was re-assembling ok. I was. The blow off works in two ways... if the boost gets too large, then the valve that sees the just-post-blower air flow opens and releases boost to the outside air...down near the passenger side wheel. On the flip side, when the intake manifold is seeing vacuum, the valve opens and release boost pressure that the engine doesn't want/need at the time.
There is a spring inside the blow off valve that appears to control both these actions..
The spring tension can be adjusted via a bolt that is top center on the blow off valve.
I turned the bolt 4 turns, tightened and down the lock nut. This compressed the spring inside the blow off valve.
I believe the net effect of this is :
1) More manifold vacuum is required to open the blow off valve (however the pressure blow off seemed to occur the moment the foot came off the pedal both before and after spring adjust).
2) The boost achieved (back at the airplane strip!) was a bit over 6, which is a little over a 20% increase from the runs before the adjust.

So, do you think I am on the right track here? Tempted to turn the adjust bolt 4 more times and see what happens.
Thoughts?

[blazen71]

I do not know the etiquette of adjusting a BOV, never had to. Either way, the fine adjustment should never effect the peak boost, just at what vacuum it starts to bleed off. In a standard system with a belt driven supercharger the valve is open or closed. At this point I think you may want to check for a boost leak. Google "boost leak kit" and get or make one. Where is your MAF located? Is it before or after the supercharger? If it's before you prob don't have a leak as you would get a CEL. If it's after the S/C and closer to the throttle body you could have a leak and you will NOT get a CEL as long as the leak is before the MAF. You could also check for a leak with a smoke machine. I still think your belt is slipping with that small 3.33 S/C pulley.

[musclemerc]

Thank you for explaining how to adjust a BOV and what the valve actually does, but I have to ask, why was this not addressed in the installation instructions from ATDR.net?

Did he make provisions for proper vacuum within his kit too?

How bout the PCV system? Does it see boost?

[blazen71]

I’ve use 2 different BOV’s that were adjustable but never had to adjust them. I believe the adjustment is more for a turbo application where you’re trying to get the valve to open at a certain psi.

[azgolfrat]

Blazen,
the MAF counter is the last thing boosted / cooled air goes by before getting into the manifold...so, downstream of the SC.
Thanks for the thoughts on the root cause here. My trouble shooting list is now
1) boost gauge correct confirmation/leak in line to gauge
2) air pipe connection leaks
3) belt slip..

Looking into all of these could lead to a number of possible solutions.. many of which you and JB have mentioned. I'll be relocating to Phoenix pretty quick here as the summer golf gig is almost up. At that point I can really go at it.

[blazen71]

Good luck and keep us posted!

[azgolfrat]

Will do.
FYI - called Vortech twice (!) this morning. The gentleman that helped was very clear that boost isnt going to open the BO valve, manifold vacuum only, so BO valve operation isn't the problem.
We talked about getting more boost out of the V7. So far I have spun the V7 up to 40,000 rpm (engine speed 5.5K). It can go to 60,000. So, I could probably get it to 9 pounds if I'm willing to get up above 7000 rpm engine speed - which I think is higher than Marty had me go in the tune session.
The other route is a SMALLER SC pulley, which will turn the SC more for the same engine speed. However, smaller diameter means more chance for slip. As you have suggested, he mentioned 8 rib. Sigh...that maybe where this winds up.
Bunches of trade offs and risks in this business.

[blazen71]

I recommended a 3.6" S/C pulley and an 10% OD Innovators West Balancer, remember? That combo will spin your S/C a little faster and most likely eliminate any belt slip. Plus you'll have a really good balancer. I was taught a long time ago to buy the most expensive balancer you can afford. It's job is to protect your engine from dangerous harmonics. You have a lot of time and money into this project, why not protect it?

[blazen71]

On a side note, if you indeed have a 3.33 S/C pulley.......

Crank pulley dia / SC pulley dia X SC Gear ratio (V7 is 3.61) x Engine rpm = S/C impeller RPM

Ø6.5" / Ø3.33" X 3.61 x 5500 = 38,756 rpm

[justbob]

Wow the gear ratio on that thing is tiny! I only ran a 4.4/8.0 pulley set up on the F1-A and we saw 20#s on 93 at only 5,700 and the wastegate was already starting to bleed off excess.

Definitely look into a quality oversized lower at minimum. I went with ATI on mine. Summit carries a wide variety of different diameters for the 4.6.


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[blazen71]

Wow the gear ratio on that thing is tiny! I only ran a 4.4/8.0 pulley set up on the F1-A and we saw 20#s on 93 at only 5,700 and the wastegate was already starting to bleed off excess.

Definitely look into a quality oversized lower at minimum. I went with ATI on mine. Summit carries a wide variety of different diameters for the 4.6.


Sent from my iPhone using Tapatalk ProI got that ratio from some random website. I just checked Vortech's website and it's actually 3.45:1.

Ø6.5" / Ø3.33" X 3.45 x 5500 = 37,038 rpm

[justbob]

I’ve only had the one centri and I was just used to calculating 5.40:1

Looking at Procharger’s site even the P1 is a 4.10:1


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[azgolfrat]

Hmmm. Makes me wonder why Vortech built the V7 with the small(er) gear ratio.
I'm using 6 & 9/16ths inches for the stock balancer diameter....couldn't find the exact spec anywhere. I wonder how this is measured? Outside of belt to outside of belt or top or rib to top of rib?, or?
In any case, Vortech does have a nice blower speed calculator on their webpage..select blower & enter two pulley sizes and engine rpm.
Thanks again guys...I will eventually prevail!
52581

[azgolfrat]

Hmmm. Makes me wonder why Vortech built the V7 with the small(er) gear ratio.
I'm using 6 & 9/16ths inches for the stock balancer diameter....couldn't find the exact spec anywhere. I wonder how this is measured? Outside of belt to outside of belt or top or rib to top of rib?, or?
In any case, Vortech does have a nice blower speed calculator on their webpage..select blower & enter two pulley sizes and engine rpm.
Thanks again guys...I will eventually prevail!
52581

oops. not balancer diameter, pulley diameter.


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[blazen71]

The stock balancer is definitely 6.5" diameter. This is just for reference, at 6k engine rpm my D1X is spinning at 52,455 rpm and I have 14psi max boost if my tires don't spin.