Jump to content
Server maintenance Read more... ×
Trent250

Tuned extractors

Recommended Posts

Agreed wagoon, but there are a few other simplified ways that let you know if you are very close or a fair way off. Also, primary length can be altered to allow for different secondary lengths, so if your secondaries aren't that volume there is likely no need for alarm (plus diameters are key).

Share this post


Link to post
Share on other sites

Like sticky tape on the collector tube and then cut them off where the tape stops burning.....

 

Many many theories.  I essence I think those extractors will work very well. 

 

Old faithful made 255@ the tyres with an off the shelf set of pacemakers with just the secondaries extended (to a volume calculation) and then straight 3".  Yes it is a metho motor but it only has 11.5-1 comp and a .583" lift flat tappet. 

 

I will be back to back dyno testing extractors on the Mad Sceintist crossflow.  Better get off the computer and onto the tools and actually finish that one and the ute.....

Share this post


Link to post
Share on other sites

While I do love dicussion and disection of ideas and theory's I found that after reading and only scratching the surface of the topic, very quickly you go from basic concepts like volume rule (which is only basic calculaton not a basic concept) into complex calculation requiring measurements that just cant be made unless you own a lab or major proffesional race team. I realised that it was good enough to use the basic rules because at the end of the day practical application needs to be the bench mark used. For example manufacturing tolerance does not allow for precise calculation to be made on volume if you can measure the difference in diameter with a set of verniers which is only a basic hand tool. Also things like distortion through welding and quality of steel used has an effect on finished product which all needs to be measured and controlled. And this is only optimising the basic volume rule, trying to measure gas expansion at given temperature and heat is just impossible.

PipeMax has 6cyl calculations for headers now so it's not hard, punch in all the head flow, bore/stroke, valves etc. and it will spit out what you need, again this is all theory, in practice just making sure there is no back pressure at all will be all you really need unless you run nitrous

 

between an exhaust with NO back pressure and irrelevant collectors and a $3000 tuned system you gain about 10-15 hp through 1000RPM range, if this is worth it then go for it, if it's not then just get off the shelf headers with the longest runners you can (pre emission and no cat had longer runners) and spend the savings on coke and hookers

 

here you really win with tuned headers is when you also tune the intake, this will need ITBs, now  you can time both with the cam and do something like, exhaust vacuum present in the header from scavenging is timed to pull air on the overlap to assist the intake and intake is tuned on the 4th order to use wave compression and mash air on after BDC. This works really well if turned for the last 1500RPM of the rpm range and can net more than 15HP

Share this post


Link to post
Share on other sites

The exhaust I made for my sedan cost less than $300 not including mufflers, and thats from primary to secondary collect to the tip including flanges, gaskets and 3 different diameter pipes. Will never know if it has made or lost power because of what I have done, but I trust the people that gave me the info for free and beleive them when they tell me it will work.

Looks like the one thing we all agree on is yes the extractors shown in the first post will work. Yes there is better ones out there and but you could do a lot worse as well. It all comes down to money in the end

Share this post


Link to post
Share on other sites

here you really win with tuned headers is when you also tune the intake, this will need ITBs, now you can time both with the cam and do something like, exhaust vacuum present in the header from scavenging is timed to pull air on the overlap to assist the intake and intake is tuned on the 4th order to use wave compression and mash air on after BDC. This works really well if turned for the last 1500RPM of the rpm range and can net more than 15HP

But you cant forget back of the valve shape as the vacuum created behind the valve effects the compression wave back up into the inlet. Also the radius of the bends in the primaries effects the speed of the wave from the first collector.

Share this post


Link to post
Share on other sites

I think I got lost, way above my head but kudo's to you guys.....

 

The average bloke just plonks a set of extractors on knowing its going to be better than stock, couple that with a nice exhaust and its good for a bit extra grunt where you need it. I cant wait to save up and get a decent exhaust for my girl as I know that will improve things again. the 6-3-1 improved my low- midrange just with the extractors, which on a stock EFI is just where I need it. I have a few months to save for the exhaust, so hoping a nice 2.5 inch will do the trick nicely with a nice free flow muffler and I am set......

Share this post


Link to post
Share on other sites

Tpack there is nothing wrong with a good set of off the shelf extractors, and while they will always be a compromise for 99% of people the will do just fine. Then if you want to go further there are some very easy modifications that will help more.

I do like the link broken wheel put up as it explains how different types of setups are suited to different uses, the info helps to understand how it all works and is a good read but at the end of the day is utterly useless unless your chasing the last 10th of a second or a geek that finds that sort of stuff interesting- Im the latter

Share this post


Link to post
Share on other sites

50mm primaries? Really? That's big unless they are really thick. Secondaries are about right, primaries should be 42-44mm.

I'll measure the inside and see how big they are... Where they bolt to the head...

Remember I did measure out sides so will be a little smaller..

So what do u guys reckon? They for high rpm or torque..

Share this post


Link to post
Share on other sites

50mm OD - 1.6mm wall(*2 for ID) = 46.8mm ID

50mm OD - 1.8mm wall(*2 fir ID) = 46.4mm ID

 

Can't imagine the wall thickness is much more than above so that is a VERY large primary pipe, although custom made may have used thin wall steam pipe. Defiantly high rpm biased as pacemaker "big bore" primaries are 41mm ID and are considered large off the shelf extractors. How heavy do the extractors feel/weigh? The ones I made which are standard pacemaker big bore primaries with 2 1/4 inch extended secondaries with 1.8mm wall and a lot of weld put in would weigh around 8-9kgs.

Share this post


Link to post
Share on other sites

50mm OD - 1.6mm wall(*2 for ID) = 46.8mm ID

50mm OD - 1.8mm wall(*2 fir ID) = 46.4mm ID

 

Can't imagine the wall thickness is much more than above so that is a VERY large primary pipe, although custom made may have used thin wall steam pipe. Defiantly high rpm biased as pacemaker "big bore" primaries are 41mm ID and are considered large off the shelf extractors. How heavy do the extractors feel/weigh? The ones I made which are standard pacemaker big bore primaries with 2 1/4 inch extended secondaries with 1.8mm wall and a lot of weld put in would weigh around 8-9kgs.

Yea right, yea there pretty heavy and pretty long.. There stainless steel if I forgot to mention it...

Share this post


Link to post
Share on other sites

Yea right, yea there pretty heavy and pretty long.. There stainless steel if I forgot to mention it...

Ok well that may well explain a few things.

All calculations are based on internal diameter-ID so will be interesting to see what exact is. Stainless has a higher heat conduction than mild steel so they may have used heavier wall pipe in the primaries to stop cracking due to heat cycles which stainless can do. Stainless weighs about the same as mild steel so if they feel heavy it may well be for the above reason.

These are my extractors which are over 900mm long in the secondaries with 1.8mm wall mild steel and as mentioned before weigh at least 8kgs, so if yours are anywhere near that weight for standard length extractors they weigh a lot.

20150428_214834_zpspq7lnptt.jpg

Share this post


Link to post
Share on other sites

Ok well that may well explain a few things.

All calculations are based on internal diameter-ID so will be interesting to see what exact is. Stainless has a higher heat conduction than mild steel so they may have used heavier wall pipe in the primaries to stop cracking due to heat cycles which stainless can do. Stainless weighs about the same as mild steel so if they feel heavy it may well be for the above reason.

These are my extractors which are over 900mm long in the secondaries with 1.8mm wall mild steel and as mentioned before weigh at least 8kgs, so if yours are anywhere near that weight for standard length extractors they weigh a lot.

20150428_214834_zpspq7lnptt.jpg

Yea that makes sense...

Yours looks killa, looks like a nice setup...

Apparently they hang a bit low and scrape on a lowered car.. So would it affect anything if I cut them down low and take a bit out so the come up a bit higher?

Share this post


Link to post
Share on other sites

Very high rpm primaries, which do not seem to match the rpm band of the secondaries.

What are the extractors you are using already?

I don't have a good pic of them so I'll take one tomorrow..

Share this post


Link to post
Share on other sites

Yea that makes sense...

Yours looks killa, looks like a nice setup...

Apparently they hang a bit low and scrape on a lowered car.. So would it affect anything if I cut them down low and take a bit out so the come up a bit higher?

It won't make a difference as you can only take it out of the secondaries. If they scrape there should be some damage on them, depending on where the damage is will dictate the easiest fix. Probably the biggest issue your going to have is finding stainless in the right size without having to buy long lengths. Measure the internal diameter with a set of verniers if you have a set or borrow a set if you can, ruler will do but needs to be a accurate one.

When I made mine I stuffed up, where it comes down past the sump and over the steering arm I didn't drop the pipe down far enough which meant the exhaust was pointing down as it went past the gearbox crossmember. All I did was go to the straight section before the collector and put in an angled piece so that it picked the collector up higher.

Share this post


Link to post
Share on other sites

Very high rpm primaries, which do not seem to match the rpm band of the secondaries.

What are the extractors you are using already?

These are the ones on my car atm...

image.jpg1_zpseeieqn3g.jpg

Share this post


Link to post
Share on other sites

It won't make a difference as you can only take it out of the secondaries. If they scrape there should be some damage on them, depending on where the damage is will dictate the easiest fix. Probably the biggest issue your going to have is finding stainless in the right size without having to buy long lengths. Measure the internal diameter with a set of verniers if you have a set or borrow a set if you can, ruler will do but needs to be a accurate one.

When I made mine I stuffed up, where it comes down past the sump and over the steering arm I didn't drop the pipe down far enough which meant the exhaust was pointing down as it went past the gearbox crossmember. All I did was go to the straight section before the collector and put in an angled piece so that it picked the collector up higher.

These are the scratches, none are deep..

image.jpg1_zpsxnce49ru.jpg

Share this post


Link to post
Share on other sites

50mm OD - 1.6mm wall(*2 for ID) = 46.8mm ID

50mm OD - 1.8mm wall(*2 fir ID) = 46.4mm ID

 

Can't imagine the wall thickness is much more than above so that is a VERY large primary pipe, although custom made may have used thin wall steam pipe. Defiantly high rpm biased as pacemaker "big bore" primaries are 41mm ID and are considered large off the shelf extractors. How heavy do the extractors feel/weigh? The ones I made which are standard pacemaker big bore primaries with 2 1/4 inch extended secondaries with 1.8mm wall and a lot of weld put in would weigh around 8-9kgs.

Measured the opening where it bolts to the head, so ports, and they were 42mm..

Share this post


Link to post
Share on other sites

colector is a bit too short... also noticed you use scorpion rockers .... good luck with them! LS1 guys been breaking them like pencils. Could be ok with a flat tappet but even with bigger lift flat tappet they break, with roller they are guaranteed to break! cheap chinese shit! they are made in china and machined in the US

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×