YenkoZ28

After having my D1SC for a couple years and looking at bolting an F1 on my Z28 this spring I'm looking at bypass valve or BOV options. Heck the ATI bypass valve in the kit won't even keep up with my D1SC and I'm getting tired of compressor surge/belt squeel when I slap the throttle shut (manual tranny). I'm looking at the Vortech Universal Maxflow Racing Bypass Valve to go in place of the stock ATI unit and maybe adding a BOV too. Will the vortech unit outperform the stock ATI unit? I take it the vorech racing valve is smaller than the mondo valve (which looks like it would be a stretch to fit in my engine compartment). Any opinions are welcome.

biggtime

I use a HKS BOV on mine. Love it I would get the biggest one i could fit. ATI makes a real big one to. I would never run anything boosted without one as it kills the compressor bearings.

Willie

iTrader: (1)

Hi Clint. I've made some progress on the conversion. About one more hour of work left and I'll be finished.

ATI's is not a BOV. It is a surge valve. I know because I inquired about it a couple of months ago. I'm currently running a pair of ATI's Pro-Flow valves, one is automatically controlled, the second is automatic too, but can be opened or closed with a switch. Until I find an adequate BOV, I'm planning on opening the second valve BEFORE letting off the throttle. Note: I only race at the track, so this should not be a problem.

YenkoZ28

Nice to hear your nearing the light at the end of the tunnel. I had a chance to drive the car with the 3bar setup finally, and it is going to take some work to get it back to where I had it with the 2bar setup. I had it up to 5 psi and my injector duty cycle was only at 30% as reported by datamaster.

With my car being a manual I need some other way to vent off excess air when shifting. The ATI proflow valve just isn't cutting it. I'm looking at hooking up a BOV to get rid of my compressor surging.

Inwo

Tial 80mm is the only answer. It even comes with a flange for you to weld on. Best. CBV. Ever.
linky

Willie

iTrader: (1)

Nice to hear your nearing the light at the end of the tunnel.

I'm getting there. I finished my knock sensor circuit adapter and my MAF to MAP adapter harness. I've labeled all the wires on all three 749 connectors. All that's needed is to solder them to the proper MAF connector pins. And of course to burn the maiden EPROM.


I had a chance to drive the car with the 3bar setup finally, and it is going to take some work to get it back to where I had it with the 2bar setup.

I suppose this was expected. How's your idle and low-speed characteristics?


I had it up to 5 psi and my injector duty cycle was only at 30% as reported by datamaster.

This is very encouraging. Are you still using the 34# low-Z injectors or did you swap to the larger Mopar units?


With my car being a manual I need some other way to vent off excess air when shifting. The ATI proflow valve just isn't cutting it. I'm looking at hooking up a BOV to get rid of my compressor surging.

Totally understood. My "fix" is a band-aid. I'm hoping by the time I can really get into some serious boost, I'll have a BOV too.


Tial 80mm is the only answer. It even comes with a flange for you to weld on. Best. CBV. Ever.

Looks like a good unit. Their website sucks though. No prices! I e-mailed them asking two questions:

1) What is the adjustability range -- Clint and I are going to need adjustability beyond 20 pounds of boost, and

2) What's it cost????

Willie

Inwo

You can pick one up at http://www.dejontool.com/dsm-misc.htm for $225 or a ton of other stores for a comparable price. It's not cheap but you get what you pay for. It comes in a selection of colors too, I have ***** red on my DSM It'll hold up to whatever you throw at it. Sheperd uses the Tial BOV to relieve pressure on his car running around 30psi without any leakage. Their website sucks, unfortunately.
The problem with most aftermarket BOVs, which should actually be called Compressor Bypass Valves due to the fact that almost all are boost sourced and don't "blow off" like some semis do when they start to overboost, is that they leak. TurboXS, HKS, just about all the bigger names, all of them aren't much better than the stock 1G DSM cbv. Half of them still have the issue of sucking in extra air when they're vented or leaking above 15-20psi neither of which are good for performance due to the added strain on the compressor to compensate for the leaking above a certain point to achieve the set boost level. The HKS "SSV" is decent, but still has leakage issues where the Tial does not, I know some people are fans of it and it's adequate but not as good. Plus the Tial is as big as a coke can so compressor surge due to inadequate pressure relief won't be a problem. I had some pictures around here but I can't seem to find them. Either way my recommendation for higher than 15psi is either a modded 1G DSM CBV or a Tial.

YenkoZ28

I suppose this was expected. How's your idle and low-speed characteristics?

Yeah I figured it would be way off. My idle is way rich and I'm a little rich in the 30-40kpa range, but it is good enough to get you down the road to do some datalogging.

This is very encouraging. Are you still using the 34# low-Z injectors or did you swap to the larger Mopar units?

I swapped to the mopar 42#/hr units, but I'm running them at 45psi instead of the rated 55psi.

Thanks for the links Inwo the tial looks to be the next item on my purchase list. I do have a question for you though. The tial stays open while the motor is pulling a vacume and closed when manifold vacume drops(floored condition)? So what is to keep your motor from sucking in dirty air through the BOV, since it is vented to atmosphere during light load conditions? Or am I not fully understanding how these BOV's work.

Willie

iTrader: (1)

Correct me if I'm wrong but it is my understanding that a BOV stays closed until a specific pressure is reached. That's when it opens and stays open until pressure is reduced. At least this is the operation I need in a valve...

Willie

biggtime

sometimes.... A bov works from pressure fluctuation. It has a base spring that keeps it closed at idle, when you start boosting it also puts more pressure on the diaphram to help keep it closed, when the pressure goes away it opens. It will also open if you hold the rpm's at say 3000 free reving as it has more air flowing throught the pipe but no boost reference to *tell* it to close. Make sure when you set it up you do it at idle. There are surge valves that just open at a specific lb but that is not a BOV.

YenkoZ28

Well the Tial is ordered and hopefully will be on my car in two weeks or so. I just wanted to thank everyone for thier input. Willie I'll let you know how it works out.