exhaust manifold info.

[Bedford126]

Right im looking to make my own manifold because im bored....

I am looking for as much info on primary lengths - internal bore diameters - wall thickness. Basically anything for the 8v. I want to choke as much mid range power out of my 8v as I can.

My mate can make me whatever bends I need I just need to buy the pipe and get welding with the Tig. Obviously the lads who know their stuff AKA sandy wont want to give info out like that and I appreciate why but your more likely to have some sort of idea where to find the info for me to read up on and trial and error it.

Cheers guys.

[saxo_turbo_azy]

Right im looking to make my own manifold because im bored....

I am looking for as much info on primary lengths - internal bore diameters - wall thickness. Basically anything for the 8v. I want to choke as much mid range power out of my 8v as I can.

My mate can make me whatever bends I need I just need to buy the pipe and get welding with the Tig. Obviously the lads who know their stuff AKA sandy wont want to give info out like that and I appreciate why but your more likely to have some sort of idea where to find the info for me to read up on and trial and error it.

Cheers guys.

mate that's easy get ur Saxo manifold off and measure ur manifold bore and the 4 holds, then u can start making it and you will need to measure inside car engine bay from block to intercooler and Check room left

[Bedford126]

mate that's easy get ur Saxo manifold off and measure ur manifold bore and the 4 holds, then u can start making it and you will need to measure inside car engine bay from block to intercooler and Check room left

Your not u understanding me mate its a n/a manifold where primary lengths and bore size is important.

[Brendan]

I believe Mikol on here might have those measurements for you. Worth a shot PMing him

[Bedford126]

Ok so I just smashed a book on exhaust manifold building. If any one could help me with the following for a Mk1 vtr 90bhp engine I would be very happy Google Isn't bringing up any answers.

-Bore/Stroke is given in inches .=

-Exhaust Valve Opening Point is given in degrees before bottom dead center (BBDC). Entered values should be greater than 0.=

-Engine Speed or Peak Power RPM For a street engine, the RPM used should be the peak torque RPM. For a race engine, the peak hp RPM should be used.=

[Prickle]

just buy a supersprint or piper lol.

[Bedford126]

just buy a supersprint or piper lol.

Why so I can be the same as ever one else? I have the skills to make a better one suited exactly to my engine so why would i buy a off the shelf item with corners cut to aid mass production?

[Prickle]

decent mani's..... thats why.

If you had said skills this thread wouldnt need to be made.xoxo

[Ross]

Totally understand. Marcus wants to build it because he can, and because the build is fun too. Niet wrong with that :)

Sorry I can't help tho dude.

[Bedford126]

decent mani's..... thats why.

If you had said skills this thread wouldnt need to be made.xoxo

Decent mani's cus you have one?

You not think that people have to research stuff before they build it.

[Prickle]

Ross - useless! xoxo

[Prickle]

Decent mani's cus you have one?

You not think that people have to research stuff before they build it.

errr...

you know the score with the dire 8v 1.6 engines tbh.

[Bedford126]

Totally understand. Marcus wants to build it because he can, and because the build is fun too. Niet wrong with that :)

Sorry I can't help tho dude.

No problems mate just missing 4 measurements now.


http://i43.tinypic.com/2e2p8d1.jpg

[Bedford126]

No you can tell by the quality of it i shouldnt need to go there with it infact i wont. Martinobviously will put us both on the correct path.

pm him.

Obviously, But your decent quality and mine is another matter. I have seen welds on piper manifolds that tbh are shocking. As I said I want to build my own to my specs with help from information provided by those in the know.

errr...

Too slow.

[Prickle]

Luckily i dont have a piper then isnt it. ;)

[Bedford126]

Luckily i dont have a piper then isnt it. ;)

as said. pointless on this forum now.

Don't get me started on supersprint.

[Prickle]

It's easy to bad mouth mani's im sure lol...

[Bedford126]

It's easy to bad mouth mani's im sure lol...

Wouldn't be so easy if they were decent though ehhh??

[danny-vts]

mate that's easy get ur Saxo manifold off and measure ur manifold bore and the 4 holds, then u can start making it and you will need to measure inside car engine bay from block to intercooler and Check room left

*your
*your
*holes
*you
*radiator

[Prickle]

Wouldn't be so easy if they were decent though ehhh??

What are the best mani's for Saxo's then lol?

off the shell that is

[manta]

sounds like a good project imo

[danny-vts]

What are the best mani's for Saxo's then lol?

off the shell that is

shell or shelf? lol

[slammed106]

The missing values will be engine specific, especially if youve altered the cam/headwork

if your that serious about making 1, get on the phone to either Simpson or Chris Tullett and see if they have any reccomendations..

[welshpug]

however do bear in mind that they will likely not want to give you anything too specific, as that's part of the skill of making exhaust manifolds, working it all out so it works ;)

if you want cam timing info look at the stockhatch or saxmax cam specs on the various cam suppliers websites.


what spreadsheet are you using to calculate the lengths+diameters you need?

[axsaxoman]

I understand what your trying to do
but you are only looking at part of the details required to get the ULITMATE manifold performance
no mention at all of induction tract --this too will need to be considered to get best compromise on ex manifold
then there is the actual ex system and where you will place your first expansion box .

but why do this with a std cmashaft spec as the real world diff on power is will be a small number .

I have done all you are trying to do when we raced the 1294cc 8v
which is hwere we came up with our 4-1 manifold design ,

all your hard work will give little gains unless you look at the WHOLE engine and set goals to where you want max torque + power before you cut one piece of piping.
take a look at std inlet manifold and straighten it out and see how long it actually is --it will suprise you and then look at t/body manifold and how short --
people will claim that t/bodies give more torque -thats not so --yes with dif cams + togther engine mods which raise total bhp (which is a combination of torque+rpm )the result may be more torque ,but just fitting t/bodies to a std spec engine will not give more torque at same rpms as std manifold .
this is why we made the downdraft t/body inlet manifold to make it as long as possible with no bulkhead mods .
our own ax have the bulkheac cut out to maximise the torque --it was 18" from trumpet to head ,. we were made to remove it a year later after winning the championship for a thrird time --the redyction in length by 150mm dropped max torque by 10lbs ft .

so your first job is to state at what rpm you want max torque and at what rpm you want max power --then with a cxombination of cam + inlet size+length
and ex size+ primary lengths +expansion in correct postion you will get what you want


look at the forums now every one promoting certain well known ex systems --they don,t even have a first silencer box and the ones that do don,t have them in the correct postion --
why cos it,s cheaper to make a system with one box --but the forums will tell you that they are the best .

I get accused by lots of people including you in the past,of being superior and just like to see my own posts --that has never been the case and i try to help .
If the car maker who knows more than me --if only because they have unlimited development facilities + money fit 3 boxs on the system ,then there is a good reason,as they try to get the best compromise of power + economy (which is effiency) they have shown you the basics to work with especially if keeping std cam.

anyone reading this with a single box system will have noticed at a certain rpm --around 60-70mph there is an anoying bumming noise from the ex system --that is because the harmonics of the gas at that rpm is not happy ,which also cuts power .
fit a front box in correct postion and it will go
.
so along with your ex + inlet manifold calcs you need to add ex system design and don,t make it too large a bore until after the first box.

the std GENUINE vts system is very good

I even did a test one day on a car with t/bodies +around 150bhp and swopped the after market ex for a s/h genuine vts sytem --the power did not drop .
yes the car had a 4-1 manifold and no cat --but so did the aftermarket system .

I then fitted a btb complete system and the power rose very slightly --not because of the dia ,but it had a first box to replace the cat as the power it made did not warrant such a large bore system
the point I am making is at least haalf the tuning parts availble are for "bling" and mix + match things at your peril .

I remember a very famous heated debate on manifolds a few of years ago and someone was going to do a proper back to back test on all the manifolds avialble .

I even offered a btb for them to test and free use of my rollers if they did all the swopping of the manifolds and i would even tweek the ecu for best output at a single rpm for free thats howconfident i was.
needless to say a true test never happened ,but the bullshit factor came to the top claiming the raceland to be the best .

the piper design manifolds are actually my designs for both 8 + 16v engines as I actually sent them cars to make the mnaifolds on along with ny spec for sizes +lengths --along time ago . and yes you say the primary lengths are not all identical ,but for normal rpms the very slight diffs make no diffenerence
I do not stock btb anymore --pricing has gone silly ,but still stock pipers and have a few btb 8v mld steel manifolds left at very special price .

I wish you luck with your endeavours but unless you do all the maths for the exact rpms where you want the max torque and bhp it will always be a compromise .
if looking for another book to read "fourstroke peformance tuning" by A graham Bell ,its a haynes book , is as good I have found that is easily readable--yes its an old book ,but as I have said many times before physics hasn,t changed

[yr51ocw]

I have taken a few measurements of a raceland manifold, and it is tuned (albeit on purpose, or not) to give peak torque at 5500rpm (ish) which is similar to the peak torque speed on a standard VTS engines, hence probably why it gives fairly good results (certainly no negative) on alot of mildly tuned engines.

The book you mention john does not have any guidance or info on the position on the first expansion box, only the manifold and the main exhaust diameter. This is also worth a good read:

http://www.amazon.co.uk/Scientific-Exhaust-Systems-Engineering-Performance/dp/0837603099

And will give you a god understanding of the harmonics involved in the intake and exhaust systems.

[axsaxoman]

you have two lengths
primaries and secondary --the first box goes at the end of the secondary length ,with a change in dia to make an anti reversionary step ,same as you should have at the head face on the ex side.
the inlet side of the head should also have one ,but the other way round ,its not a mistake on the car makers design that the manifolds do not line up perfectly it is intentional,but again we are talking very small differences ,there is no magical 15% gain with one mod to be had

[Bedford126]

After a hour of talking on the phone this morning with a exhaust builder for a famous bike engine builder I will be going for a few days with him in September so he can explain the maths and science around building them.

Cheers john for the info. The reason I am building it for the standard head at the mo is because all the info is out there and it turns out my head is from high flow heads so is not the best so I have a xsi head ready to be built once i know what im doing and what power i am aiming for.

[axsaxoman]

jsut bear in mind that bike engines have bugger all torque and even in std form are highly tuned compared to a car engine and all use multiple t/bodies ,due to cam durations they use
not a cooking slogger type of engine as a vtr is

[Bedford126]

jsut bear in mind that bike engines have bugger all torque and even in std form are highly tuned compared to a car engine and all use multiple t/bodies ,due to cam durations they use
not a cooking slogger type of engine as a vtr is

I know what your saying and the bloke i will be going with said the same but he also said the calculations are all the same and he will try and teach me what i need. And tbh im never going to say no to some one when they ask if i would like to go work with them for a week. He builds manifolds for Superbike's and quite a few TT teams.

[stevie_m]

What material are you using mate ? Seen a few manifolds on here such as JP's that is metric pipe and some are nominal bore pipe.

I've started to try and fabricate a few merge collectors basically because I was bored at work, Merge Collector (http://honda-tech.com/showthread.php?t=2787713) I seen this and it made it a helluva lot quicker. I've just made a metric sized collector and this week I shall be trying to start the NB one this week.