HonDaKillaH

anyone know where i can get a COMPLETE blowthru setup? i have a s4 turbo motor and wanna do a blowthru setup. any info on this will be appreciated

Rotospeed

iTrader: (8)

For a compleat set up you would need to find one used. If you have a turbo motor why don't you go efi using the stock parts from a tii?

PercentSevenC

Everything is custom. Build it yourself or get someone to build it for you. Or buy someone's used setup. Or do EFI because it's better anyway.

LizardFC

iTrader: (1)

If you have an S4 turbo motor, just stay EFI and use the S4 ECU.

seanrot

iTrader: (2)

You're gonna have to piece it together yourself. Plenty of info on here for all you'll need. I'm in the process myself.

Jeff20B

iTrader: (13)

As am I, going blow through Nikki or Holley. I thought about going EFI, but nope. Tried it and found out I didn't enjoy the experience.

My blow through 4 bbl should solve all the issues PercentSevenC's blow through DCOE setup had, and be far more enjoyable than EFI was.

LizardFC

iTrader: (1)

What didn't you like about EFI? My main reason for going blowthrough was the added expense of engine management.

Jeff20B

iTrader: (13)

Well I already have engine management. I even enjoyed the process of wiring up all the stuff to get it running. What I didn't care for was tuning on a laptop. It just didn't turn me on like a carb does.

I didn't get into rotaries some 20 years ago to fiddle around with fuel injection. I got into rotaries when the typical upgrades on a rotary truck was a streetport with a Racing Beat Holley 550 and a free flow exhaust. Upgrading from points to electronic ignition was an exotic mod. I never considered an EFI upgrade or even turbos back then.

Maybe I'm limiting myself to some extent by choosing to not embrace EFI these days, but I have a feeling the same thing will occour; I'll spend way too much time and money locating all the parts to make an EFI FD setup run and drive in a 1st gen chassis, only to stop liking it when tuning time comes around. So I'd rather go carb and keep it simple. I can swap in an FD rotating assembly into a set or R5 plates and old school housings. Then an S5 NA flywheel will round out the package.

As for making it run, a semi-locked dizzy that only advances to 10 degrees is better than a fully locked dizzy set at 10 degrees all the time. A 4bbl carb is better for driveability than Percent's 2bbl weber ever could be. If I use the boost prepped Holley I got off the forum, its total CFM is greater than the weber as well so I should reach my power goal. If it doesn't work, I can boost prep a Nikki without any difficulty.

You see, a blow through plays to my skill set. Maybe that's what's going on here? But the other thing is I'd like to see if I can improve on Percent's setup. So I'm in it for two reasons. Oh and I might try the MegaSquirt in a rotary truck. A little ironic after reading this post, I'm sure.

HonDaKillaH

i dont wanna go efi because i didnt want to deal with all the wiring and computer issues..i think jeff has a good idea going carbd..

84stock

iTrader: (5)

I felt too old to learn new tricks too, that's why I went with a Camden. Always dreamed of twincharging it one day.

Off to do a dark side trial first though.

LizardFC

iTrader: (1)

My main concern with the blowthrough is detonation. A hiccup in the fuel supply could potentially blow seals. With no knock sensor and ECU to electronically retard the timing, you're at the mercy of your fuel system and boost spikes. During my last autocross, I blew a fuse and lost power to my fuel pump. The carb ran out of fuel while I was at WOT. I can't imagine that would have gone well under boost. Some sort of boost retard would make me feel a bit better.

Another idea I've had is a bleed valve on the intake to keep boost right where I want it. I'm using a stock S5 turbo with an internal wastegate, which even when ported can be prone to spike. I'm thinking with a one way valve on the charge pipe with a spring set just right, I could bleed off excess boost. You can't do that with EFI since the air is metered, but I figure it won't make a difference to a carburetor. Think it'll work?

Jeff20B

iTrader: (13)

Yeah, that could work. Kinda like a BOV/wastegate combo or something. But more like a controlled air leak?

Yeah I plan to use an S5 turbo, but I also have an aftermarket turbo and a real wastegate. The S5 could go in my REPU so I can use its internal wastegate and not have to plumb quite so much in a small area. The aftermarket stuff could go in the 7 where space is a little more available.

LizardFC

iTrader: (1)

Yeah, pretty much. A boost leak that I can control. I already have a bleed valve boost controller that will probably work. I'll just run it on the charge pipe instead of in the wastegate circuit. It's designed for the correct boost ranges so I shouldn't even need to swap out springs or anything.

S5 turbo REPU, that sounds like a lot of fun!

Jeff20B

iTrader: (13)

Yeah I am mostly interested in how quickly it can spool; the S5 turbo. PercentSevenC was getting his to spool either right above idle or literally at idle. Crazy. And it had insane low end torque. Not even my 20B (NA) could compete. So I'd like this type of turbo in my REPU for obvious reasons.

Plus since I've got a set of S4 NA rotors in it currently, I could take advantage of their 9.4 compression ratio to spool it even faster. The only problem is installing an intercooler in a meaningful way without ruining the bumper supports or the lower air dam oil/cooler area. Funny thing is Percent was running this turbo on his streetported R5 13B at 10psi without an intercooler! R5 rotors are 9.2 CR so that's like pretty close to 9.4... right? Maybe if I kept the boost at stock wastegate pressure (7psi? or close to it?), maybe I won't need an intercooler.

The other option was to use the FD rotors in the REPU so I could get away without an intercooler more safely, but I'd rather use them in the 7 with a big front mount intercooler and really crank up the boost. The S5 NA flywheel is a pretty good match to an FB chassis at 21 pounds, but I'm fine with a light steel as well. I'm not fine with a light steel in the REPU. However the S4 NA at 24 pounds feels right. I suppose an S5 NA at 21 pounds can work fine, but the 24 pounder didn't feel heavy or anoying at all. It was a good match.

ArmyOfOne

iTrader: (12)

Im in the process of building my blow-through setup right now. Using S5 turbo on my combination port motor. Upgraded fuel lines to 1/2" and am running a Holley fuel pump through a Mallory boost referenced FPR. Last thing I have to do is modify the throttle plate on the Holley to feed pressurized air to the throttle shafts and that's it.

Having a blast building this.

theNeanderthol

iTrader: (1)

I am going to use AEM's new wideband controller on my carbed turbo setup. It has the ability to trigger a failsafe when the afr reaches a dangerous level. It looks at rpm, boost level, and afr. You set parameters (you can actually set a curve, not just simple parameters), and if it breaches them under boost, you can make the trigger cut the ignition, bleed off boost, or both. That way if you get fuel system trouble, overboost, air sucked in the fuel line whatever, you can save your engine. It even datalogs 3 hrs of data. In case it triggers a failsafe, then goes back to normal, you don't have to guess at what triggers it, you can look back and know for sure.

AEM Performance Electronics Wideband Air Fuel Failsafe Gauge - Wideband O2 UEGO, Water/Methanol, Stand Alone Engine Management, Piggyback F/IC, Tru Boost Controller, Gauges, Automotive Performance Electronics

I'm glad they came out with it. It eases my mind a lot. My big fear is making a small error, and killing the engine. I'll feel more comfortable with this guy working it's magic.

ArmyOfOne

iTrader: (12)

Thanks for the link. I have an old school Innovate LC-1

seanrot

iTrader: (2)

I think it's called a pop off valve. Spring loaded cylinder that lets boost spikes escape. Tension adjusted by torquing the bolt down.

One on the left is the hks version for the 12a. On the right is the sigma version for the 48 IDA.

Jeff20B

iTrader: (13)

Excellent ideas. My car has a 3/8" send and 5/16" return using a walbro 255 and a GSL-SE gas tank. I've got a mallory boost referenced fpr ready to install. I'll also add a remote fuel pressure gauge so I can watch it shoot up from the driver's seat. That should be cool to look at.

I've got a question about adding pressurized air to the throttle shafts. My boost prepped Holley already has some holes and a channel connecting them to a tube but I'm not sure where to hook up a hose to feed the pressurized air. Do I add it from the carb hat or from ther charge pipe? Or how about under the carb like on the manifold or something. Remember I'm a total noob at this boost stuff. Things that may be obvious to most people aren't to me when it comes to this particular subject. Thanks.

Jeff20B

iTrader: (13)

I've heard of a pop off valve but never seen one. I thought it was another name for a BOV. Guess I was wrong.

LizardFC

iTrader: (1)

That was my reasoning to go with the S5 turbo as well. That and it's cheap My first gen is an autocross ****, and this year I'll be rallycrossing it as well. So having boost kick in at low RPM can mean the difference between being able to pull out of a tight corner in 2nd or having to make the drop to first. I can't imagine building a turbo rotary with no intercooler. I know the 12AT didn't have one, but still... all that hot air! Not only does it kill power but it raises internal engine temps and increases the risk of detonation. To me, a good intercooler seems as important as a good oil cooler. Not sure where I'd put one on a repu though. I'd probably vent the hood and go V-mount.

That's pretty cool! How are you planning to use the failsafe output? Maybe cut power to the coils?

Looks like I'll be running a 3/8" return and the stock feed. Also going to leave the stock return on the carb. I wanted to run a 1/2" return but the only line I could find in that diameter was aluminum. So I ordered some 3/8" steel hard line. Gonna start building the fuel system this week. I'm using a Walbro 255 with an Aeromotive FPR.

Jeff, I'm not sure how to go about pressurizing the shafts either. I was just gonna seal everything else, throw it together and see what happens And I've always heard pop-off valve used to describe a blow-off valve.

LizardFC

iTrader: (1)

And excuse the double post, but I just had another idea for that failsafe wideband: If you wire it to a relay that cuts power to the leading coil, you can essentially create a crude boost retard as long as you are running a split. The trailing will continue to fire at the designated split, + the degrees of difference between the plugs themselves.

Which brings me to a question. Is cutting spark at a certain AFR and boost level enough to stop detonation? You're still drawing in fuel and air under pressure which can be ignited by combustion or hot spots. And you can't really cut fuel with a carb unless you close the throttle. Another option would be to wire it to a solenoid that opens a bleed valve, or even the wastegate.

I might have to order one of those kits and put the wideband I have in the vert.

theNeanderthol

iTrader: (1)

Yeah, I'll cut power to the coils. I'm also playing with the idea of having it cut power to the coils, and bleed boost at the same time... Not sure. I'm going to leave the dizzy unlocked and use 2 timing retard devices to cut timing under boost too. I'm not meaning to clutter the thread, but I really think these failsafe tricks can be the key to having a blowthrough (or drawthrough) carb turbo setup that doesn't blow up during carb tuning. Jets too small? Oops there goes the failsafe. Less terrifying than "oops there goes the motor"

85rotarypower

This is all pretty interesting and I also like the idea of keeping it simple with a carb setup. Seems to fit with the age of the vehicles too. But here are my thoughts on ignition.

Not sure if such a device exists but what are the possibilities of an ignition only ECU for electronic distributor less ignition? Should be very simple to setup with 2nd gen CAS and coils and furthermore simple to tune based on simple timing curves. Fuel can be tuned through the carb and the ignition controlled by the boost level and RPM. Would provide excellent retard control as well based on manifold pressure.

EDIT: Just did a quick search on Megasquirt's website and it seems they don't offer ignition only control. This is of course the only research I have done on the matter, but maybe its something that could be requested?

Jeff20B

iTrader: (13)

Well I'm not going to vent the hood.

Hmm, if I go with the S5 turbo in the REPU, I'll probably run without an intercooler, at least at first. I'll keep the boost at stock levels, keep the timing at no more than 10 degrees of advance, and get the high octane fuel. And if and only if that sounds too risky and/or expensive, I'll just stick with a nice NA setup and a long primary exhaust.

It's about the reliability and usefulness of a truck (the bed, the towing capacity etc), not about constantly worrying whether I'll pop it this time I take it out, or the next. I don't really need a second headache, I mean a boosted project when I'm willing to go all out with the FB, you know? It's just that the truck can be boosted, and I'm sure it will respond well. Not that it should be boosted. Plus the fact I've never actually done one of these before, so there's a huge 'unknown factor' at play here. But I've got a boosted project in me that has to get out, so I'm willing to put in the time to build something like this and see how it responds. Just not sure it should be the truck.

I already know how it responds NA and with a Camden, so the next step is boost from a turbo which I know will beat the Camden at any RPM. My only hang up is just pretty much zero experience in this area.

Wait, that's it! I have to do this because I have no experience! I mean the FB is like so obvious, but the truck is a big unknown. Well, I pretty much have to now. Oh wow.