Rb25de (supercharged) Project

[TiTAN]

give the exhaust gasses somewhere to expand and cool.

[r33_racer]

Yeh it is quite tight. Gonna have to pull some magical fab or machine work out of my arse to get it together nicely.

I was hoping to get the wastegate part all welded tonight, but we spent all night trying to find a stupid miss with the race car. It seems like an injector or maybe two are not playing the game!

In regards to the 4" dump pipe, pretty much as TiTAN said. Im attempting to cheat, but utilising 4" to dissipate enough heat so by the time exhaust gas reaches the 3" its not choke up.

[r33_racer]

Woot! Got the wastegate outlet welded up and onto the dump.

Time to move onto the next PITA part. Outlet to intake doo dah! Hooray

[TiTAN]

thats a huge waste gate pipe 2.5" ?

[r33_racer]

Dude you are on the ball!

Yeh 2.5" it is!

Well since im only running low boost out of it, it needs to pass alot of gas. I need the wastegate to control boost perfectly and without any silly issues from undersize piping or improper placement.

[r33_racer]

Took the better part of the day but I got the turbz outlet to charger inlet done! Thank god that part is over, it was quite daunting thinking I wasnt going to be able to fit it together.

Tomorrow will be the 4" turbo intake and hopefully start the catch can (lol which I forgot about) and then I think thats the twincharge fab work done!

Still left with engine stuff to do, hooking up the power steering and water/methanol injection kit!

[Craved]

Nice work!

what's your trick for welding the thin wall pipe to that thick plate?

[r33_racer]

Cheers Chris.

That pipe actually has a 3mm wall lol. So its not so bad. The donut sections are more like 1.2mm I think. But I just focus the arc below the joining points and once the heat gets into the thicker parent metal I just move the arc towards the join when feeding the filler and it just melts up onto the pipe nicely. The donut onto the compressor cover was more difficult. That cast just doesnt like melting nicely.

[Craved]

ahh ok, looked thicker on the flange plate. Just did some 10mm alloy to 3mm sheet during the week and it was a hassle lol

[swarzee]

Awesome build so far, totally enjoying the thread and learning lots too. You must have the patience of a saint to get this far and not be able to drive it =) Looking forward to checking back for updates and seeing the finished product. Congrats so far and good luck with the rest!

[r33_racer]

Thanks mate! I am itching pretty hard to finish this thing so I can drive it.

I got about half way through the breather can tonight.

Its basically going to be a mini dry sump tank, with 4 lines going in, one from each rocker cover and two from the crankcase, and then one line (from the pipe tee'd off the middle one at the bottom) down to a one way valve and into the exhaust just after the 4"-3" reducer. I'll have a pipe cut with a 45 deg end sticking into the exhaust at 45 degrees and flush with the centre line so I can take advantage of the fastest flowing gas(centre of the tube - Poiseulle flow) moving past it, generating the maximum amount of vacuum through the attached line. I believe Bernoulli's principle has something to do with how this setup works.

Hopefully it works well. This setup has been around for quite a long time apparently, but ive never seen anyone take advantage of it, atleast not around these forums. The old fellas who schooled me about it said he was doing it to race cars back in the 70's and 80's, I guess dry sump setups and vacuum pumps took over afterwards.

[Craved]

they didnt have catalytic converters back then though either - any chance of issues with unburnt oil gumming up the cells?

p.s. love the effort you're putting into this - gotta love being able to make shit for yourself

[zebra]

Could plumb in just after the cat, "should" be a low pressure area too (in theory)

[r33_racer]

lol...what cat?

But yes, if you were running a cat, then you would put it after that point.

You are not wrong Chris. It is cool, though Ive never known any different. Everyone in our family has been of the do it yourself mindset. But the same old guy who told me about the exhaust evac setup also said if you have an inquiring mind you can pretty well do anything. This guy was a chippie by trade, but spent 30+ years of his life as a race car builder!

[Craved]

wanting and having the means to do are different things though unfortunately.

re: oil/air separator - at what temps does oil burn? there must be a point along the exhaust where the oil vapour would not turn to ash and simply burn off and carbonate at a later stage under longer periods of load (ie track day)

are you running a catch can along with the separator? im guessing not since you have no more room left lol - just thinking in terms of a cat bearing road car.

[Craved]

oooh ohh another thing, exhaust backpressure if it occurs will cause your dipstick to mimic a bullet once crankcase pressure builds up - it is easy enough to test the back pressure but its probably something you'll need to ensure there is none throughout the rev range at the point you input the breather tube

though im sure you already knew this lol

[r33_racer]

wanting and having the means to do are different things though unfortunately.

re: oil/air separator - at what temps does oil burn? there must be a point along the exhaust where the oil vapour would not turn to ash and simply burn off and carbonate at a later stage under longer periods of load (ie track day)

are you running a catch can along with the separator? im guessing not since you have no more room left lol - just thinking in terms of a cat bearing road car.

I suppose having the means makes it easier doesnt it.

Depends on oil, but probably a couple hundred degrees. I think the flash point is the proper term. I guess that is possible, if the exhaust was so hot it would just vaporise the oil vapour. But how is that any different to oil bypassing rings, turbo bypassing oil and burning, or dodgy valve stem seals letting oil into the chamber? Essentially the samething is happening except alot worse. I think if its setup right there shouldnt really be much oil burning in the exhaust, im hoping it will mainly be air! Lol but my can may not be upto scratch and I might find a shit load of blue smoke billowing out the exhaust.

That breather can is my catch can and seperator. The way im hoping it works is the oil will settle at the bottom and the air will rise to the top and get sucked out the opening at the top of the middle tube, go back down and out the tee'd in bit at the bottom and go out to the exhaust via the one way valve. So if it works properly then hopefully the air wont be carrying as much oil as usual. That is the plan anyway.

I will be putting a drain bung on the bottom and a capped off dash 12 weldon on the roof incase it needs a filter or something if there is a problem.

[r33_racer]

oooh ohh another thing, exhaust backpressure if it occurs will cause your dipstick to mimic a bullet once crankcase pressure builds up - it is easy enough to test the back pressure but its probably something you'll need to ensure there is none throughout the rev range at the point you input the breather tube

though im sure you already knew this lol

Yeh thats going to be the tricky bit, as im going to take a stab at where to put it, rather then testing the exhaust system first. However if there is sufficient back pressure then im sure ill have power making problems as well as that issue, but as the easy fix I can just put a filter on the -12 on the lid as a temporary fix until its sorted properly.

lol or just go and buy a stupid vacuum pump and get 20+ inHg of vacuum through the motor! But that would be too easy.

[bigmikespec]

Come on Mike, you know you want to http://www.starvacuumpumps.com/

[Rolls]

Can you put a one way valve on there to avoid exhaust getting into the system?