Jeff20B

iTrader: (13)

If blow-through, go Nikki all the way. 100%

If draw-through, I couldn't tell you as I have no experience.

The stock FC turbo has a carbon seal. I don't know if this is useful info to you. I've rebuilt a couple and yes, it has a carbon seal that you can swap out for a new aftermarket one in the kit.

Skyl3r

Well, most people I've seen go drawthru seem to use a Holley. So I have no idea yet.

And yes, it is useful. Thanks! My only concern with that is it's probably gonna be a little difficult to find a FC Turbo laying around. I'll look though. Ford/Mopar/Dodge/Chrysler are gonna be pretty easy to come across.

wankel=awesome

My draw through will use a side draft, of the 1bbl variable venturi variety...

Qingdao

iTrader: (3)

Say whaat? FC turbos are all over the place. Cause none of the second gen RX7 owners want them. They want big turbos that take forever to spool.

Skyl3r

I only did a quick search on eBay. I'll check some local groups. Thanks for the heads up!

Qingdao

iTrader: (3)

Keep your eyes open. One will show up on ebay or the classifieds here. They usually go for about $250 for a good one. $100 will get you one you can rebuild or has broken studs.

^^^ that's for S4 the "lesser" turbo.


I'm not sure which FC turbo you are after.

wankel=awesome

I will find some more on the subject, but heres a hint on the fuel drain..

wankel=awesome

and btw, you can't leak boost into the manifold that is receiving positive pressure. the drain only works when it's under vacuum, when boost isn't present.

the Elford draw through kits built without it were ALL retrofitted to the drain in 83. 100% recall.

j9fd3s

iTrader: (3)

unfortunately its not. this is one of the biggest troubles with the engine. it'll make noise at part/low throttle, but at full throttle its tricky. there are a few reasons for this, its mostly temperature related. it is best to keep mixtures a little over rich, that way you have some margin if its a cold day/overboost/bad tank of gas, etc. plus you want cold spark plugs, and run conservative timing. if this was mine i'd start tuning with the timing about 5 degrees retarded, get the fuel sorted, and then maybe add a little more timing and see what happens.

this goes double for a setup like this that can make big power, but has no safeguards.

if it was mine i would do it. i share your skepticism, but they are doing it for a reason.

par for the course! you should get a larger fuel pump, the engine will want more fuel. if i had to get another fuel pump, Walbro makes one that mounts like the stock pump, so install should be easy.
https://walbrofuelpumps.com/walbro-g...fuel-pump.html

the carter works, but mounting it sucks. the holley pumps are loud (like spoons in the garbage disposal).

for the carb, i'm pretty agnostic, although it does need to be sized right, 390 holley would be fine, or such like.

for the turbo the FC's HT-18 should work pretty well. i'm running one in an FC right now, and its a great size for a rotary on the street. the powerband is 2500-6000rpms, right where you drive. plus the manifold is a little grinder work away from bolting on, downpipes are available off the shelf, so its a nice option.

the Ford T3's are too small, the Rotary needs more exhaust flow

Skyl3r

I see, that makes sense. The thing is I've read multiple guides on drawthru's that haven't mentioned any such thing and there's people like jim_chung who don't seem to have anything like it and have been running with no issues. I'm just very hesitant to drill a hole into the turbo.



Well that sucks :P
Thanks for the suggestions though! I'll have to get familiar with timing before I pull the trigger on this build. I'm still pretty much in the planning phase, as it's got a pretty big scope.

Yeah, after hearing everyone else's suggestions I'm definitely gonna be getting a new pump. I'll check out the Walbro.

I was originally intending on getting the Holley, and I'm still considering it. Since I'm not going to be daily driving this car so I don't know if the sound would bother me or not. That said after hearing like 3 people now say don't do it, I have to wonder if I shouldn't do it haha



I've been going back to the drawing board on parts list. On the advice of a few friends I am going to try to use the Holley 4412 carb. If it ends up driving terribly, I'll probably swap out for 390cfm carb and use the 4412 on a future project or sell it. I got it real cheap, so I'm not losing much there.

I found some 12a flanges on Amazon going for about $70. I'm almost to the point of just doing my own header. I can get the turbo flange and the 12a flange and the pipe cheaper than the Turbo Exhaust header I was looking at before.

That said, I kind of wonder if it wouldn't be worth just sitting the turbo on the preexisting exhaust flange because the hose for the intake is gonna be much cheaper than the flanges and such for the exhaust. I'll have to look at the physical fit and check prices to see if this is physically possible.


It's kind of amazing how fast prices start racking up. With boost and A/F gauges, headers, pipe, carb jets and gaskets I'm at $1100 already. Now throw on top of that a Turbo, potential adapter flanges, fuel pump, fuel lines, oil lines, and various tools to get the job done.

But after seeing my buddy's built turbo Mustang, I know this is gonna be worth it. And I also know I'm gonna need a bridgeport to beat that thing

Jeff20B

iTrader: (13)

Oh dear.

Skyl3r

Yeah, me too.

Jeff20B

iTrader: (13)

You're looking in the wrong places to make good driveable power. Don't bridge port it. It's a compromise port for when your racing class doesn't allow peripheral ports.

My blow through Nikki and 74 spec port job already feels quicker than my friend's corvette, so I'd say save yourself all this headache and go blow through. Let wankel=awesome experiment with draw through to see if it's even still relevant these days. But I understand you already bought the parts and want to try it yourself.

There's gotta be a reason people don't do draw through much anymore, and it's not just due to the lack of new carbon seal turbos being made these days, or the difficulty in intercooling. I don't even use an intercooler on my blow through setup so it's not that. Well, good luck.

Skyl3r

I thought peripheral ports were more involved and GREATLY decreased the life of your engine?

This website (Porting) lists the disadvantages and advantages of BP and PP as:

BP:
PRO'S: Very good potential for power, increased rev-range
CON'S: Poor drivability, fuel consumption and excessive noise

PP:
PRO'S: The ultimate form of rotary porting for maximum power
CON'S: Excessive noise, extensive intake mods, very poor drivability and fuel consumption, relatively short engine life, very expensive, narrow power band


Are these accurate? The cons here are what led me to decide on bridgeport.


So there's a bit to this in my mind.

As far as why I would do this instead of blow through, it comes down to a few different things.

Despite what I've heard several times, blow through is more expensive. Saying you don't need an intercooler for blow through isn't really a valid counterargument. I have serious doubts that you'll be able to run 14psi without an intercooler on blowthrough. These numbers are achievable on drawthrough. Then add in the fact that you don't need a BOV as well.

So essentially as I understand it the difference in equipment would be on drawthrough you need the manifolds, but don't need a BOV, intercooler, and you don't need to boost prep your carb.


The downside as I understand it with drawthrough is:

• Consumes more fuel than blowthru
• Turbo lag because of the addition of fuel running through it
• Turbo has to have carbon seals (potentially requiring a rebuild)
• Carbon seals are not used anymore because they are not as good as dynamic seals (I'd have to go back and find out why)
• Decreased drivability

That said I had some other ideas for spooling the turbo quickly and drivability isn't a concern.
I do fully acknowledge that a blowthrough can allow more boost, spool faster and is more versatile.


If I were to speculate on why drawthrough seems to be limited to mostly old VW's these days I'd guess that it's because:

1. A serious lack of information
2. People who don't really know declaring it to be an absolutely terrible idea
3. A significant decrease of carbed vehicles making it irrelevant

I mean google Drawthrough and you'll have to sift through pages of people saying things like "You really don't see why that's a bad idea?" then you'll stumble across a VW guy running 9's in his drawthru beetle, then more pages of condemnation.

My takeaway has been nobody does it because everyone condemns it. When someone actually does do it, they aren't terribly disappointed.

j9fd3s

iTrader: (3)

sort of like your blow through vs draw through findings, the P port is subject to a lot of misinformation. the majority of people who ran P ports, were racers in the 1980's. that is a select group of people, and it was a LONG time ago.

engine life was short with those engines for two reasons, first they spun them to 9,000rpm (+). more RPM = more wear.

the second reason is that they ran carbon apex seals, per the book, these seals are good for 600km of racing miles. this is much shorter than the stock iron seals which will do 60,000km's without a second thought.

i've done a couple of P port engines, and i've found if you take the time to tune it for part throttle and low rpm (a LOT of time!) drive ability is actually quite good, its not as nice as stock, but its much better than you'd think. the bridge should be in similar waters, the 80's racers didn't care if it would go down the street at 25mph, they never tried to do that.

for a turbo though, everything changes. if you have a turbo that is small enough to be fun on the street, it'll have some back pressure. the trouble with the BP and PP engines is that they have a lot of overlap, the intake and exhaust ports are open at the same time, for a long time. when you have back pressure this is bad. the engine ends up recycling exhaust gasses into the next intake stroke, and you loose power, at best.

the best port for a turbo, is actually the stock one, or maybe the 74 spec ports, these have minimal overlap, and thus the engine is much more tolerant of back pressure

as an example the factory ran a bridge ported turbo engine, it used TWO turbos that were bigger than the stock FC turbo. it makes lots of power, but it was also complex and unreliable.


i found the same with the P port, when i did mine. i'm sure if you keep in mind the limitations of the kit, it should work really well. the key part of that is that this kit lets the engine make enough power to hurt itself, but has no safe guards, so YOU need to make sure that the setup is safe.

partially, your limits are a lack of an intercooler, you will want a cold air intake to the carb. second is that with a restriction in front of the carb, it makes the turbo work harder, it changes the pressure ratio. this shouldn't be a huge deal, the carb and turbo are sized ok, and you're not trying to make a zillion psi of boost.

or put plainly, best results are when the COMBINATION of parts works together. i'd think once you have all your ducks in a row it should be really happy around 10psi/200hp

Skyl3r

Very interesting. So, am I to take it that if you're going to bridgeport, there's no reason to not just go all the way and PP? I guess that makes sense. I recall reading that somewhere before, but I wasn't sure. It may actually have been one of your posts.

I've seen posts on here (that I'm struggling to find now) showing BP Turbo owners' dyno sheets making 280-310hp. This is the sort of range I was hoping for.
You say lose power... Is there a risk of damaging the engine involved? It sounds to me like it would just decrease how much fuel and oxygen could get in there, not actually blow anything up. Am I wrong?




My goal for boost is 10PSI and if I can get up to 14 I'd be real happy, but 10 is okay with me.

Huh, a CAI with a carb... I hadn't thought of doing this. I guess you'd use something like a carb hat and just attach a standard CAI to it?
I'll have to research this.

EDIT:
On some further inspection, it's looking like Spectre Performance is the only one making CAI kits for carbs. Has anyone used one? Are the decent?
I saw criticism claiming they don't actually move the intake away from the engine, so you're not really getting cooler air. Any thoughts?
Here's some I was looking at:
http://www.spectreperformance.com/se....aspx?prod=743
http://www.spectreperformance.com/se....aspx?prod=761

Qingdao

iTrader: (3)

Also, add to your price of turbo, better tires, better clutch, and rear end. Cause those things are much needed over the stock stuff. I've found out recently about buying these annoying extras.





I really think the VW guys do draw throughs just because its been done before and its easy to tune. I almost did a blow through solex on my last 1584 engine build, but someone bought it from me before I could weld up the exhaust. Blow through solex has been done too quite successfully.






I found blow through to be cheaper. Just because I already have the intake manifold and carb to do the job. I'm still using my factory stock MX6 BOV I got from the junkyard for $6 so that's not terribly expensive (I pocketed the other hoses for the Turbo->intake). I ran about 8#s on that no problems (although I don't have a temperature gauge to measure intake temps)




Ultimately what is your goal for this car? Are you gonna weekend drive it, or are you going to race it or dd?

Skyl3r

Oh yes. You are correct. I've found a bit of info on doing a Ford 8.8 swap, which I may end up doing. I'll have to see. That's not my plan immediately. It probably won't be going through any 6k launches in it's first month or two of running.
I'm gonna start keeping better lists of stuff.







Yeah, I think I'm gonna have a similar experience of finding drawthru cheaper because I have the manifolds already.
My goal is occasional weekend use and racing. It will not be a daily driver.

lx_machado

iTrader: (13)

My car has been running for a little over a month now with the Arkay set up, I'm only running 7psi, no launches, just 2nd thru 5th gear pulls and my rear end just **** it self. All of your old worn out stock parts start to become a problem when you add this much power.

Skyl3r

Ah that sucks, but thanks for the heads up. I guess I'll make this a higher priority than I originally thought it was. Do you have plans for how you're going to beef up your rear end?

Qingdao

iTrader: (3)

I'm not going beefier on my rear. Just not near enough traction with an open diff.

Also I want to leave some mean 11's on the pavement around work.

My clutch bit it a few months ago. I drive like a bandit and that clutch was out of a pile of parts I had when I built the engine. So it probably wasn't the best idea to use it.


If you have the manifolds and the carb... shoot go for it.

Turbo, regardless of how you do it, will eat up money though. Totally worth it.

I'd go with a regular old 74 spec or mild street port if I were you. I just hear BP's are aggravating, and aggravating takes the fun out of the experience. Unless you are a super rotary buff.

Skyl3r

Well, I was reading into it a little bit after lx_machado's message and apparently people have taken the stock rear end to 300hp alright. I guess it's really just a lottery though when you're playing with a 37 year old car.

So I'm gonna try to use my stock rear end and see how it goes.

I was reading about people's BP Turbos and they were making them sound like a blast. I recall hearing:
"Once you hit 6k RPM's it's like the second turbo kicks in"
I don't know though, I've never even driven a street port haha.

Jeff20B

iTrader: (13)

I'm purging all streetports from my rotary stable. Like all noobs, I went for streetports in the beginning and noticed a drop in performance. Fortunately I stuck with rotaries instead of writing them off, and tried 74 spec and stock 12A spec next, and was not disapointed. Then I went for boost and while it wasn't easy, it has been the best thing I've ever done with my life (in rotaries). My setup is very modest, too.

I'm already at corvette levels and plan to push it only a little bit higher. Currently at 7 to 9 psi, my clutch is slipping. My tires break loose on dry road while still in primaries. When I open the secondaries, that is when "a second turbo kicks in". I would not change a thing about my setup other than the clutch because I need a stronger one now. I might eventually add an intercooler. My stock LSD is holding up well enough but I do feel a slight looseness. Not bad for 31 years old.

Skyl3r

What? Losing power from streetports? I've never planned on doing a streetport, but all the same this has intrigued me. How are you losing power?
Why didn't you try the stock port before streetporting?

Maybe I misread something. If not I'm confused lol



This is exciting to hear. It sounds like a lot of fun. I've never driven a turbo car before or even been in one and I'm dying to know what it's like.


I've began slowly ordering parts. I'm hoping to have everything late January or early february and having the setup ready to roll when the snow melts in Spring

Skyl3r

Just a quick follow up.

I've ordered most of the parts and I am quickly understanding why people look at those $800 ebay kits suspiciously. I've hit the $1800 mark and I'm suspecting another $1000 in parts.

Anyways, what I've got so far:

• Carb - Holley 4412 500CFM
  
• Turbo - Borg Warner S200SX (I also ordered a carbon seal rebuild kit)
  
• Intake Manifold - CarTech kit
  
• Exhaust Manifold - Rotary Works manifold
  
• Wastegate - I ended up going with a Wyntonm ebay wastegate. Everyone was saying they work well and haven't had issues, so I'm risking it.
  
• Fuel Pump - I did end up getting the Walbro GSL395

Everything should be here by next week and hopefully I'll start installing around that time. If I come up with anything interesting I'll make a write up as there seems to be a lack of information on drawthrough right now.

Thanks for the suggestions and help!