Ported blower,datalogs..Boost problem + cog belt system?

Hi!
some of you might remember me from threads regarding rebuilding and porting eaton m90 a few years ago..now it´s been in my car for 2 years..I recently went to 2.7 ratio pulleys

and now I´m loosing boost after 4000-4500rpm depending on a pull..allready made ultragrip pulley for blower but only some help I think..(sometimes can now smell the rubber..no sound tho´ like it used to have)

Boost gradually goes down from 19psi to 14psi

I would like some opinions of you pros who have datalogged boost etc. curves what is happening for boost..it looks little spiky (Map).

Belt slip still?
too small airfilter(could be, not the best)?
too small exhaust(2x2"-3" now, maybe not)?
overdriving the blower? (this would be weird..but plausible..?)

Here are some datalogs and dynopulls
(powerdyn is street dynamometer program, Tatech is local tuning/dyno shop)

http://palkki.oulu.fi/%7Esamila/dynot/

On Tatech pulls teh car went out of fuel and was still without the ultragrip style pulley, now I have 2 fuel pumps before the new 044 bosch arrives..so powerdyn figures are up to date.

max torq in lbs/foot is now about 340nm with 4000rpm and max hp around 290hp at 4500rpm-->

Really need to sort that dip out because the hp curve is just not right/okay...
Ignition tuning does not help after 4000rpm, no knock, no HP gain.
Fuel is still little too rich...

I have asked an offer for a cogbelt system parts and that´s in the building program for the next summer..

PS: the car is BMW 325i cabrio -86 with ported eaton m90 and 2.5L straight six..(had last summer the blower with 2.3 ratio and 11psi, 1/4 mile 14.1s, 104Mph, No traction thru first gears, could go 13.5s etc with slicks)

some pics of the car (last show) if someone is interested:
http://palkki.oulu.fi/~samila/hts2007/

It´s the green cabriolet bmw e30

Hope you can help and give some opinions how to gain some more boost/Hp
Biggest problem for now is the boost drop and why? Is it the belt slip still..?

I´m planning to do this winter head porting, installing more agressive cam, headers and fabricating new 3" exhaust all the way..and off course the cog belt system..

19 psi? what kind of intercooler are you running?

I'd say you definately have some slip going on. You either need to get a shorter belt, stiffer tensioner springs, an additional tensioner, or get some cog pulleys and a belt.

Is it ran off the main serpentine belt?

Read through posts from Kevin Leitem in this thread.
http://www.sccoa.com/forums/showthread.php?t=81346&highlight=belt+slip+log&page=2
He has a link to a site that will allow you to rig up a way to monitor blower rpm, and from that calculate the amount of belt slip you are seeing.

thanks, I´m using basic, cheap, china made FMIC, polished, with 18x14x3" core.

It´s a Bargain..One dude has tested these cores and they are in good reputation for efficiency. These are almost "industrial standard" here now days

I think going from 89´F->117´F is somewhat acceptable with 20psi..Just have to mod cold air intake etc. to get the basic numbers down a bit.

Have to check those links and make a monitor for blower speed..I have some extra channels in msns or tech edge logger..

Datalogged the exhaustheaders and had about 14psi of exhaust pressure at 6000rpm..

have to fix that..restriction somewhere..(sound baffles in rear end)

Try to datalog the blower rpm tomorrow..I can post the schematics if someone wants them when I know the circuit works.

datalogged the blower and can I see about 7-15% of slip after 4000rpm..
New Figures out of engine with 1.05bar are 310hp/475Nm 5100/4000rpm with more free flowing exhaust..trying to get 350hp

I´m making a cog pulley set during winter time and making the engine breath better.

Why not try a ten rib setup? Also what kind of tentioners are you using? Perhaps OD the crank more and the blower less for more belt contact

Id use a cog as a last resort

I have been thinking about the 10 rib system..but I can source really nice cog belt system for fraction of the cost of 10 rib system..

My tensioner is not so good(solid,turning around snout/attached to the snout), but I´m little tired of fighting with the belt slip problem..

I´ve always had some because it´s custom made system and not much room in the engine bay anyway..10rib might not have enough room also.

Here is a link to datalogs and dyno...You can clearly see it in the one datalog when the by pass opens the blower speeds up and when teh blower speed tapers down..don´t worry about the scale..it´s logged using EGT channel ..but it´s 0-5.v channel (0-1000'C = 0-18 000rpm about).

http://palkki.oulu.fi/%7Esamila/dynot/

here are some pics more of the system..
http://palkki.oulu.fi/~samila/ppf/

and here you can find a picture of the unfinished tensioner..
http://palkki.oulu.fi/~samila/ppf2/

PS: now with more open exhaust I can hardly hear the blower anymore ...so a cog belt system should take care of that too ..
I can post the schematics for the datalogging circuit here if someone wants them..but it´s not suberbly linear. So only as a guide line. I could try to figure it out why it´s not linear..

I think it has something to do with the reflective tape system. I Think that the phototransistor signal varies during rpm a little as it "sees" narrover section of tape at higher rpm:s.. 14$ for all parts(with enclosure) to get 0-5.v out so not bad tho..

IS there some reason for not going for cog belt drive other than the sound?
+possible destruction in case of blower lock up..

cog setup is generally rougher on your blower and your crank.

Another thing I have noticed in the past is that a good belt is key

From what I understand about cog systems is that the belts tend to be less than 100% reliable at these pulley speeds.

In my testing I found that it is normal for a poly V belt to "walk" on the pulleys. Under all conditions of transition both acceleration and deceleration you will see a difference in rpms between the blower and the motor. About 3-4% is typical on steady state acceleration and 10% is not uncommon on quick transition.

You mention that you are running a non spring loaded tensioner. That will never work on a poly V belt because they stretch with RPM. A cog belt may work better in this case because they do not stretch.

You definitely seem to have belt slip on at least some of your datalogs.

I notice that you still seem to be running 100% duty cycle on your injectors. I don't see any AFR data on your logs but you will find that if you want to be able to accurately tune your AFR you'll need to get that down under 90% duty cycle.

It is typical for the blower to reach max boost early, then fall off slightly as engine efficiency reaches max followed by a final increase in boost as engine efficiency drops off at high rpm. The blower will always have a more linear VE curve than your motor.

definately need bigger injectors and fuel pump, as well as the tuning to make the injectors work right. What size MAF/injectors/fuel pump do you have?

Curently boys..hmm..how can I say this..I will post the video soon.
I blew out my belt today..(maybe too little engine )..
here goes the same story as to the swedish ppf forum:

Last day without snow (I think..) in Finland

Could not help my self for not to take some video of burning my rear tires and I did some ignition tuning as well..BEHOLD!

I got this as last resort..then put some more ignition..no help..BLEW the BELT OFF the blower ..took my engine trigger too with it and my blower logger (2.5e) optocoupler..So there we were with my friend standing at the highway, but smiling

I have this dyno run and the one when the blower belt detorated in my datalogs..have to post them later..too exited now! here you go..found some lost Nm in the low end too ...tuning is nice..tho this baby won´t get a new belt until next spring!

I post pics off the belt remains+video here too and the datalogs..

Man, it just blew off..Made something like tire popping sound..luckily it did not make too much harm. Have so much things there in the engine bay now..so that kind of protected everything else. Blower rpm..well I think around 18 000rpm when it let go..8 rib belt..I guess this is the end of the road with that..

just as I let the throttle go and it picked some traction..POP!



Rest you can see at:
http://palkki.oulu.fi/~samila/dynot/

definitely I had some belt slip..but I think my grip pulley took care of that for now..happily I only lost my ignition trigger and blower optocoupler in the process..that´s motorsports..

Here is the old 8rib belt..



You can see all other data at the website except the video..I´ll post that soon here.

PS: 336hp/481Nm engine today..not bad for 2.5L
any advice welcome. no matter what engine you have..a nice blower this is

PPS: thank you for all your advice during these years..it´s been worth of gold!
The car has map sensor..injectors are out I know, they flow 42lbs(fuel pressure now only 36psi), 044 bosch fuel pump is allready ordered, now running dual pump setup.Runing now with pwm modulated injector control so I´m not frying the injectors..Have to raise fuel pressure or get a new set of injectors.