tortuga

I think the 1 psi per .1 pulley drop is kind of a rough general rule.

matt270avian wrote:

Ah alright, makes sense now. If you do the math, 1 psi per .1" in pulley drop, you should be at roughly 23lbs. Lose a couple for port, exhaust, etc. and the law of diminishing returns, that puts you at about 17-18?

I tend to believe that having significantly higher flow through the engine buffers the affect of over-driving the blower another pulley size in addition to simply counter-acting boost. (for the same reasons that you won't see a 1psi boost increase per .1 change in pulley on say a 6 liter v8 engine running an M90) Meaning I don't get the 1psi/.1" pulley anymore.

It depends on your breathing mods, and the size of the pulley. The 1 PSI per .1" pulley dia drop came from modding a stock pulley on a stock car, because that's what generally happens. But an engine modded to breath very well can make 400 HP with only 8 PSI boost - it's possible.

Another factor is % of total pulley diameter. For a 3.8" pulley, moving to 3.6" (-.2") is a 5.2% decrease. A 2.5" pulley dropped -.2" to 2.3" is an 8% decrease. Expect a proportionately larger boost bump with very small pulleys.

17-18 PSI is far above the M90's efficiency range. Instead of boosting that high, try increasing cylinder compression, or advance spark timing.

AA wrote:

It depends on your breathing mods, and the size of the pulley. The 1 PSI per .1" pulley dia drop came from modding a stock pulley on a stock car, because that's what generally happens. But an engine modded to breath very well can make 400 HP with only 8 PSI boost - it's possible.

Another factor is % of total pulley diameter. For a 3.8" pulley, moving to 3.6" (-.2") is a 5.2% decrease. A 2.5" pulley dropped -.2" to 2.3" is an 8% decrease. Expect a proportionately larger boost bump with very small pulleys.

17-18 PSI is far above the M90's efficiency range. Instead of boosting that high, try increasing cylinder compression, or advance spark timing.

I wouldn't be surprised at all if I could made the same power at the top end with a larger pulley - less boost with some other tweaking but I really like having the added abundance of power in the lower ranges.

Just dyno the freaking thing already. Yeesh   

tortuga life

On jan 26th, I inadvertently tested how many usable gallons of fuel my tank actually is. I was driving on E for a bit and then had to drive across a few towns to get to E85. There aren't that many around me. I was running on bubbles for a couple blocks and I knew it because aside from the car's behavior and + fuel trims I could hear all the air going through the fuel system clearly. I actually made it all the way to the gas station pump by the skin of my teeth. It finally died out not 20ft from the pump and I was able to get another start out of it and weasel it up there. Anyway, I filled it with 18.22 gallons from that point so there ya go lol.



I've been wanting to get a 2.5" belt wrap pulley so I can run the 3.2 without taking off the whole belt wrap but everywhere I looked online I could only find fancy billet stuff going from $60-$100. Screw that noise! I made one at work and pressed in a bearing from another spare pulley. So far so good! Being I'm not super experienced with press-fit tolerencing, I had to kinda go with intuition on how tight to make it to the bearing. So far it seems perfect. If you have enough tensioner/idler pulleys, you can run just about anything on the supercharger with just one belt size. I might even make a little 2" one for shits & gigs.

Otherwise nothing really new. I have to drain my PCV oil/water catch can at least every month or it'll fill up (sending water or oil to the pcv for the engine to ingest instead of crankcase air) and in the summer that's no problem but it sucks in the winter especially since I'm not in the garage. The thing is the water always sits at the bottom of the can and drains easily but the yellow oil substance sitting atop the water in the can is very viscous and won't drain unless you have the engine fully heated up and you give it some time. That aspect of it makes it a pain in the ass so just a warning to anyone. I should mention that in the thread about it - i know. One day, I would like to find or make a much bigger can to give me more range between draining.

This winter has been unbelievably more brutal than any other before. Ridiculously cold all the freakin time and more avg snow. I am really really glad I have snow tires because they are amazing but this temperature! I probably spend 1/5 of my gas warming up the car.

Last night when I got out of work, my car didn't start. The ignition and everything powered up but when I turned the key to start, absolutely nothing happened. No cranking or clicking or anything. It suspended accessory power like normal and just did nothing to the starter. Lights didn't dim or anything. The batteries were fine. I tried a bunch of times and just before I was about to talk back into work to get a long screwdriver to jump the s terminal on the starter with, it just decided to work. That pisses me off more than anything cause now I have nothing to fix and I'm just gonna be waiting for this to happen again. I feel like this has happened before long ago and it was just a loose connection at the battery or something but I could easily be remembering wrong too. I think before I just lost all power when I tried to start which would make sense to me but this thing last night really doesn't.

Oh yeah.. I guess IL doesn't do emissions tests on 1997 vehicles anymore!!    Thank you somebody!

That's really bad-ass! You need to figure a way to sell those.   

turtleman wrote:

Last night when I got out of work, my car didn't start. The ignition and everything powered up but when I turned the key to start, absolutely nothing happened. No cranking or clicking or anything. It suspended accessory power like normal and just did nothing to the starter. Lights didn't dim or anything. The batteries were fine. I tried a bunch of times and just before I was about to talk back into work to get a long screwdriver to jump the s terminal on the starter with, it just decided to work. That pisses me off more than anything cause now I have nothing to fix and I'm just gonna be waiting for this to happen again. I feel like this has happened before long ago and it was just a loose connection at the battery or something but I could easily be remembering wrong too. I think before I just lost all power when I tried to start which would make sense to me but this thing last night really doesn't.

I once had the terminal and nut on the starter itself that leads power from the solenoid to the actual starter motor loosen a bit on the 98. It would randomly do what you describe. I only found it when changing what I thought was a bad starter, but all I needed to do was replace the "spark blasted" lock washer and tighten it up. I had the starter off when troubleshooting, and dang that wire and post would get HOT when it was trying to move the starter motor by arcing across a bad connection. Not saying that’s what yours is, but if your starter isn't original it might be something to check.

Quote :

Anyway, I filled it with 18.22 gallons from that point so there ya go lol.

Yeah, I've recorded about the same. My largest fill after running out and adding some from a gas can was 18.290 gal.

The largest fill I've had with engine coughing on fumes (LTFT pegged at +16.4) was 18.446 gal. It actually stalled and coasted about 20 ft in neutral to the pump, similar to your story.

AA wrote:

Quote :

Anyway, I filled it with 18.22 gallons from that point so there ya go lol.

Yeah, I've recorded about the same. My largest fill after running out and adding some from a gas can was 18.290 gal.

The largest fill I've had with engine coughing on fumes (LTFT pegged at +16.4) was 18.446 gal. It actually stalled and coasted about 20 ft in neutral to the pump, similar to your story.

I would imagine that extra little bit you get is mostly because of the smaller fuel rail volume and running gasoline vs e85 but actually that's kinda good to know I'm not doing thaat bad in the hurtin for fuel state.

Could be, or maybe the metering at different filling stations is a little off.

There's always that. Since I've switched to E85, I've been recording all the gas I've been putting in. I always try to be scientific and kinda do the same thing. I let it fill up only on one click of the trigger (I read somewhere that less air bubbles flows out that way and affects the meter. I used to never top off or squirt any more gas in after it stops itsself the first time. I've started to do it now because it seems to add a little bit more before it cuts off the 2nd time and i'd like to have that extra little bit. So I make a note in my speadsheet saying "1 extra squirt" or something haha

I always fill to the first click. It keeps logs more consistent, imo. I record all my fill-ups using Car Care app for iPhone. I used to do the extra squirt, but I don't like to chance overfilling and getting fuel all over the place.

I decided to try out a one-way clutch alternator pulley in light of it being increasingly common in the industry now. I got a part meant for the '04 grand prix & 4.2L vortec engines to test. If you're interested in this, there's plenty of documentation out there now about one-way alternator pulley systems aka overrunning clutch, sprag pulleys, OAD or decoupling pulleys. Overall it requires minimal modification to work on our CS140? alternators. I was originally interested in making a custom hub to fit such a bearing to my supercharger but after talking to Paul (PRJ) tentatively determined there's no bearings out there that are strong enough and small enough to work for that.


Try to forgive the annoying belt squeak in the video. This is an unrelated issue that has been plaguing me for a while.

I made the necessary spacer sleeves and shim at work to save a few bucks but you could buy them just as well at a hardware store. Basically you need two things. You need one spacer/washer to go between the new alternator pulley and the alternator fan since the pulley and fan can no longer be allowed to touch each-other and you need three 3/16" thick (big enough I.D. for the M10 studs and suggest 3/4" O.D.) spacer sleeves to move the alternator out. 3/16" is the max you can go with for those sleeves because with any more, there is no clearance between the alternator fan and the accessory belt tensioner pulley. The spacer for the pulley should be 1/8"-3/16" thick to have decent belt alignment and enough pulley-shaft contact. If you're purchasing that pulley spacer, it's probably gonna be closer to 1/8".

The new pulley I used is smaller in diameter than the one I took off so that means I'm over-driving the alternator. I'm figuring that this along with the free-wheeling action will give me better charging voltage stability while my engine idles roughly. I do have occasions where my alternator cuts on and off due to loosing rpm which is kind of annoying. We'll see how much this helps.

Some general advantages: per Litens Automotive Group
extended belt life and increased drive system component durability by up to 2x
extended tensioner life
quieter accessory drive system operation
smoother accessory drive system operation
reduced vibrations in passenger compartment

Foreseeable downsides:
adding another maintenance item
expected service life of pulley may be shorter than spec due to this being a larger alternator and modified engine
over-driving the alternator technically robs a tiny bit of power [it's entirely possible there's a closer size match than the part I used]

That's some pretty neat stuff you got there turtle. I like your belt squeak. Our cars must be twins....I have the same exact noise. Run soft wire brush on the underside of the S/C belt. I bet it goes away for about a day then comes back....

Abaddon wrote:

That's some pretty neat stuff you got there turtle. I like your belt squeak. Our cars must be twins....I have the same exact noise. Run soft wire brush on the underside of the S/C belt. I bet it goes away for about a day then comes back....

Yeah that belt squeak was like the final knife in the throat to why I gave up on trying to make it to the half mile last year last-minuting everything. When I first started the car up after my head gasket job and all that, it started out quiet and then that squeaking came up and got LOUD. I really thought it could have been a bearing or something in the engine at the time which is why I put the wrench down and went to bed at that point (4am or so). I originally misdiagnosed it as my alternator bearing and then after finding nothing wrong anywhere, I just decided to try replacing the belt even though mine wasn't too old and looked fine. This is a very crappy job to do by the way because even with the modified engine bracket, I still have to take it off because the 8-rib s/c idler pulley in that area takes up all the room that you would use to slide the accessory belt out through. Anyway it was quiet for a decent while and now this squeaking came back towards the end of winter. I hate it but I am not replacing that fuckin belt again.

I hear ya. Exact same thing man. I replaced the belt, which was quiet all summer. Then one morning, SQUEAK SQUEAK SQUEAK!!!! I can get it to go away for about 3 hours. Then it comes right back. I ordered a new tensioner today, as I didn't like how mine felt when I released it to take the belt off the other day. It had a "hard" spot right when I pulled on it, then it got smooth. I have a feeling that it has a "memory" worn into it. We shall see what happens tomorrow.

This clutch drive you're experimenting with...I'm assuming it's for cars with crazy camshafts and lopey idles. I can't imagine any sort of benefit to a DD. Please correct me if I'm wrong. I love the concept of it as long as it stays together while your foot is on the floor   

I had that belt thing driving me mad for a while too! I think slipping the belt off and taking a wire brush to clean the pulleys helped resolve the problem. Also look to see if there's any large chunks in the grooves of the pulleys. I had some and removed with small screwdriver while turning by hand. At least you will know from this point it IS your belt for sure.

I'm gonna probably try cleaning stuff like you say. When I had the belt off, I was using a toothbrush with brakecleaner and got a lot of black off my p/s pulley although I think a lot of that was just old caked on belt dressing from when i was trying that before. I'll go through all the accessories and belt and clean everything really good once I have time and a nice day which I really hope will be soon. It hasn't been loud or anything lately but just enough to remind you its there.

Today, I put the car in the garage and took off the throttle body adapter to take with me to work and bore it out oversize to match my oversize northstar. I measured my hand port & polished blower inlet and thankfully it's big enough. I measured 3.105" across, 3.100" diagonals, 3.095" vertically which is actually perfect - a bit over 78mm (basically 78.74mm).
I measured my adapter plate as is (actually I polished it a little bit a while back but that doesn't really affect dimension) and it's about 2.952" now which converts to 74.98mm. I just need to bore it bigger and I can put it back on and install the 78mm northstar throttle body tomorrow morning for initial testing.


That's actually the difference in size if you compare the marking on the adapter plate there with the bore between my blower and the adapter. It's clearly non-concentric as there's no keying or anything to place it perfectly which didn't ever matter with the size difference. Now I'm going to have to get it nice and concentric when I reinstall the plate to the blower. If I have time, I might try to make some quick alignment tool to basically shove in the bore so I don't have to play with it - just tighten the screws and done.

In other news I pretty much got the whole new tuning approach about down. I'm already dialed in roughly. Basically I have the AFC set at 90% to scale back the raw maf hz coming in so I don't max that out again and I have the maf table numerically scaled 70% with the injector flow table counter-scaled the same to get the calculated air mass numbers down too since I was hitting both hz and calculations limits at the track last October. The downside is that means my VE table doesn't work anymore (I could fix that though) and the numbers I scan from maf or injector duty are no longer actual - I have to do math if I want to know what's being represented. The car is responding just fine with the scaling. I also went ahead and bought a TAC harness from zzp to get the TP sensor-derived torque information more accurate seeing as I already have a bigger than stock throttle body and it's about to get bigger yet. With the addition of that, I may have to tweak transmission tables a tiny bit but as is, it's pretty good; I mainly just get shifts a tiny bit later now since the PCM is seeing a slightly higher TPS given my actual foot input compared to before. At some point though after I finalize the maf tune and make sure I have enough head room to not max anything out again, I'll probably ask PRJ or TEP Dave about dialing in the transmission for good. That's one thing we were waiting on before when I got the new trans.

So far, the overrunning alternator pulley is working out nicely. I noticed the other day when I just floored the engine for a second and spun the tires, when the rpm quickly came back down as the tires started to grip again, I heard the alternator spinning and winding down which was kinda neat since I distinctly know it's doing its job in that condition. Otherwise I never hear anything.

Good job with the tuning! What you have had to figure out is not an easy task.

Thanks Deek. Yeah I'm relieved that it's working out so far. Getting to the track again and squeezing an 11 out of this is somewhere in sight now..

I managed to get the throttle body adapter done and installed today. Just need to dress the new throttle body and slap it on tomorrow morning (ok later today technically) so I can take the car to work. Was planning on riding the ninja to work but my room mates dad accidentally took my keys with him and who knows when he'll be back - he's a truck driver. So with the sealer between the blower and adapter curing, I should be ok tomorrow afternoon to drive it.

Some shots I took 'cause I dunno


blower cleaned and ready for the adapter


Yeah I made an alignment tool for installing the adapter


letting the rtv skin a little - you may notice here I machined the part of the adapter off that would be covering up the coolant ports at the bottom which I obviously am not using ever


I pushed it into place from the alignment tool, tightened the screws, pulled the tool out and wiped off excess sealer - done


nice alignment


applied thread sealer and reinstalled nitrous nozzle

The rest later..

turtleman wrote:

Getting to the track again and squeezing an 11 out of this is somewhere in sight now..

You mean 10? lol

matt270avian wrote:

turtleman wrote:

Getting to the track again and squeezing an 11 out of this is somewhere in sight now..

You mean 10? lol

I wish. I believe 11's could totally happen. 10's no way. I think like one GP guy ran a 10.9xx in an M90 build and that was i'm sure missing a lot of weight, slicks, etc.

Wow, the progress looks awesome! I understand being realistic about ETs (breaking 11s vs. 10s). While it would seem shaving one second is a consistent challenge, %-wise it gets more difficult the faster you go. Dropping from 12.00 to 11.00 requires a 8.4% improvement in time, while dropping from 11 to 10 secs requires a 9.1% improvement. And I'm sure there are other factors which make it even more of a challenge.

Having said that - 11.X ET is stupid quick for a Riv or any FWD car - or any car period! No need to go any quicker if you still want to drive the car on the street.