Wastegate Spring Pressure

[65Cobra]

Now that I'm almost finished with an upgrade of the Mr Turbo kit on my 99 Busa, my friend and I are wondering about the wastegate spring. The Tial 38mm wastegate came with a 10 lb spring and we're wondering if I need to change it to something lower.

The only engine mods consist of (all APE products) high volume oil pump gear, main bearing stud set, cylinder studs, one piece clutch cam pusher with springs, valve springs & retainers, cometic multi-layer steel head gasket, and manual cam chain tensioner.

The "only" Mr Turbo items that remain are the header and rajay turbo (both in excellent condition) and even the turbo has been upgraded from an FF40 to an EF40. Everything else was replaced or upgraded, including the fuel pump (Bosch 044), plenum (hand made), BOV (Tial Bv50mm), Power Commander (newer USB model), Wastegate (Tial 38mm), exhaust (open with no muffler).

With this setup my friend is concerned the 10 lb Wastegate spring is too much but I'm not sure what to think. On one hand, this is my only bike so I'd like it to last, but on the other hand I don't plan to baby it all the time either. Considering my setup, should I go with a weaker spring? Any idea what numbers I'm looking at?

As a side note, medical problems kept me from riding for years so this bike has less than 8k on the odometer. That's about to change.

 

[thepushercg]

cut it back to say a 6 or 7 pd spring i run a 10 on mine but mine is a tab bit more moddified

 

[Moparict]

If you aren't running a spacer and studs, the 10# spring might be a bit much. 7-8 tops probably and 6 to be safe.

 

[kawiboy11]

10 seems very h???igh

 

[65Cobra]

Pushercg, what additional mods have you done?

Moparict, I installed APE studs but not the spacer, so is there anything else I need to keep the 10 lb spring besides a spacer? I'm also curious how much of a power loss the spacer made in the low to mid range.

Any ideas what horsepower range I can expect with a 6-7 lb spring?

Thanks

 

[65Cobra]

CORRECTION:

Sorry, I just realized the spring in my wastegate is not 10 lb, but rated at 8.702 lb, although I still need to change to something lower. According to Tial's website my choices are 5.802 lb or 7.252 lb.

 

[The Big Red One]

Pushercg, what additional mods have you done?

Moparict, I installed APE studs but not the spacer, so is there anything else I need to keep the 10 lb spring besides a spacer? I'm also curious how much of a power loss the spacer made in the low to mid range.

Any ideas what horsepower range I can expect with a 6-7 lb spring?

Thanks

Go with an 8lb spring...you'll have almost as much power as you'd get with a spacer and 10lb spring....but you'll still have the awesome busa low end grunt off boost

 

[ogre]

run a 5 psi spring and pick up an electronic boost controller. you can modify the boost by what gear you're in, so 5 in first, second, 7 in third and fourth, then whatever your full boost is in the top gears. i had 3 separate boost settings in my srt. 7 in first, 14 in second, and 22 psi in 3rd, 4th, and 5th. run as much boost as you can without picking it up, so your bike will be as fast, but as safe, as possible. or just crank the sucker and pray, up to you

 

[ogre]

oh, here's a couple decent boost controllers, and why i like each...

AEM - TRU-BOOST Gauge-Type Controller
aem tru boost. gauge type controller, scaleable led's plus digi readout. two boost levels accessible via scramble switch (high boost "go" button)

the cons are no boost by gear, that's about it, nice ebc tho.

Apexi AVCR

apexi avc-r
had one of these, boost by gear, overboost by scramble button (if you like), 3 user adjustable boost maps availible (3 separate boost by gear maps if you set it up right), adjustable duty cycle solenoid for boost response adjustment, 3 data displays (graph, numerical, analog) and you can display up to 4 parameters at once with the proper sensors. needless to say, super sick ebc.

the bad: it's a ***** and a half to set up properly

http://www.rx7store.net/product_p/turbosmart e boost.htm
turbosmart eboost

direct quote, since i have no experience with this one, i've heard it's fantastic tho

"The latest in Hi-tech electronics, featuring a 16 bit RISC based FLASH memory CPU – faster and smoother boost response, utilises the latest in surface mount technology – lighter, smaller and ultra compact, electronics are housed in an anodised billet aluminium alloy housing – offering durability and reliability in harsh race conditions, programmable gate pressure function to totally eliminate wastegate creep - you tell the wastegate when to open, three internally or externally activated and individually programmable boost set points, drag racers - improve your launch, run a different boost in each gear, high accuracy boost and vacuum display, readout accurate to within +/- 0.5% of full scale, boost gauge no longer required – great value, readout can be tailored to suit your needs – display can be configured in KPA, Bar or PSI, easy to read seven segment display with programmable bar graph and glow in the dark buttons, programmable auxiliary output – e.g. water spray control, water/methanol injection, boost light, programmable audible warning alarm – excellent for over-boost warning or full boost confirmation, peak hold/max boost recall function, revolutionary gauge type construction allows many practical mounting solutions – 66mm in diameter 55mm long, suitable for panel mounting, or in any 2 5/8 inch gauge pod or pillar mounting system.
sensor"

the cons, über expensive


now, there are certainly other ways of regulating boost, but i prefer the easy adjustability of an electronic boost controller, as well as the fine tuning that can be done with the proper unit.

 

[ogre]

oops

 

[OZBooster]

I use an e-boost,on one bike and a boost by smith type on another
e-boost is great, but somewhat complicated to programme till your used to it, many more features than i will ever use, not waterproof.... big downside... but the upside is easy triggering of the next boost level, in either sequential with 1st as reset for drags or 4 stage direct grounding the trigger wires (diodes needed for the 4th stage)

Boost by smith type is simple regulators and solenoids,waterproof, just about foolproof , only downside is its a little bulky compared to an electronic type, but great value for money.

Ogre if i read the info about the aem right its manual select on boost levels ??
wish they would make it remote switched ...cheaper version of the eboost if it was.

 

[DropBusa]

Dude just run the 8 lb spring. Dial it down if your concerned. Otherwise run some HIGH octane. VERY VERY HIGH octane if you want top end runs to survive.

 

[rocketgeezer]

Anything over 6 with stock comprestion, is to much unless your going to run C-16 or something like it all the time, for a street bike, pump gas, do not run over 6 lbs boost or you WILL be fixing a meltdown, also keep in mind 6 lbs will melt something if your maps not right, with a spacer you will be able to run 8 or 10 lbs with no problem

 

[65Cobra]

Although I didn't expect such a wide range of answers, the last thing I want is to blow the motor. I don't want to run any fuel that isn't easy to come by. I want to stay with 93 octane pump gas and at most, an octane booster than can easily be purchased locally. According to the instructions from Mr Turbo, the idea was to always use 93 octane gas, but an octane booster wasn't necessary if I was just casually riding. That appealed to me, although I ended up using an octane booster fairly regularly anyway.

I'm not using any type of boost controller and I'm not in the market for one at this time, but I would think there's an inexpensive way to keep the 8 lb spring and, as DropBusa says, "Dial it down"?

 

[OZBooster]

You can't reduce from spring pressure but you can increase,
your right i lost the main fact behind this thread, std comp..pump gas... 8 psi max fairly safe , 6 safer, less fun...
Don't know what your wheelbase is, but on std wheelbase i used to like 4 psi first, 6 second and 8 for the rest... then i got greedy and put a +4 arm on

 

[goodluck]

run it between 6-7 you should still see somewhere around 250 horse even on pump gas

 

[65Cobra]

Not that anyone has to stop posting, but thanks for all the comments, including the ones on the boost controllers. At the moment I'd just like to get riding again, so I'll change the spring to something safer and finish the few items I have left.

Next year I plan to replace the steel header and Rajay turbo with a stainless header and a ball bearing turbo. That will likely do it for me... unless of course I change my mind, ha.

 

[The Big Red One]

You won't believe the difference between a ball-bearing turbo and the old style bush-bearing types as far as spinning them in your hand. The ball bearing takes just a little tweak from your fingers and it'll spin forever....way way longer than a bush type. I can only imagine how much quicker it's going to spool up on the bike. I think its going to be WAYY more responsive than my last turbo......and I'll know in a couple of weeks

 

[65Cobra]

You won't believe the difference between a ball-bearing turbo and the old style bush-bearing types as far as spinning them in your hand. The ball bearing takes just a little tweak from your fingers and it'll spin forever....way way longer than a bush type. I can only imagine how much quicker it's going to spool up on the bike. I think its going to be WAYY more responsive than my last turbo......and I'll know in a couple of weeks

What was your last turbo and what turbo are you replacing it with? After you try it out, I'd be very interested in knowing what you think. Thanks.

 

[The Big Red One]

What was your last turbo and what turbo are you replacing it with? After you try it out, I'd be very interested in knowing what you think. Thanks.

My last turbo was an old school mitsubishi bush-bearing style, the new one is an IHI VF-22 dual ball bearing style thats going on my 14. The difference between the 2 free spinning them was shocking But you have to remember the bush styles ride on a layer of oil which works as the bearing.....so I'm sure they'll spin much different running and lubed than dry I will def let you know the differences I can tell between the 2 though...should have it up and running in a couple of weeks