Manifold design

[SKiddell]

Yeah both pipes are independant they dont rossover anywhere not even in th rear box. is this a good or bad thing?

Dont get too fixated with the 3rd crossover perse, its more about secondary length....the "twice pipes" system has ample secondary length...about 10 feet

 

[jay28]

Those twin pipes are 2".......is that too big?

Also the 2 centre box's, are they just for extra noise reduction or do they have another function?

 

[Ian Patmore]

Still would consider 1 5/8" even if stroker, there is a DJ stroker with this size, running VERY well. Sean what have you got on your DJ engine? Especially as your engine won't be screaming up that high all the time. Engine has to be running very well to go to 1 3/4" size. Jay, what head work have you had done (exclusive of skimming and cam) as I don't see any mention on this thread. If none done, far more important than exhaust/header. But the choice is, yours...

Just my toughts....

 

[jay28]

I know what your saying Ian..........Just been reading a few other threads on the new and im now swaying towards the 1 5/8 primaries.............no real head work worth talking about , I suppose a very light port and polish but its was really just a good clean.

I want to leave the head as is on this engine as I dont know what head I'll be using for the stroker yet, whatever head I do end up using will have a propper port and polish.

For now I just want to upgrade my exhaust system, and want it to also perform well with a stroker.

1 5/8 primaries and a 2" twin system is what im leaning towards at the moment.

Got a price for collectors too, 320 pounds plus vat, so I'll be making my own .

All they seem to be is 3 long radius elbows cut at an angle to form 2"

 

[SeanDezart]

I have a 1 3/4" manifold.

 

[samuri-240]

Jay I think you will need a manifold to hand so you can copy it, just trial fitted mine, it is quite a snug fit !!! its not like the other brands with loads of room around them.You must be very sklled If you can make one of these, it may be an idea to knock several of them out while your at it, there would be plenty of buyers for them.

 

[jay28]

Well I can take a measurements from the engine in the car, my header is very close to the chassis / suspension leg, only about 5mm clearance.

I send off the auto cad file today to the place that has the water jet cutter. They have a minimum charge of E150 so I got 3 sets of flanges cut out of 12mm 316L for E170 so thats not too bad.

I'll do my own first and see how I get on, I'll order my pipe next week.

Also the p90 head has square ports so gonna have to try make a square out of a circle

 

[samuri-240]

Well I can take a measurements from the engine in the car, my header is very close to the chassis / suspension leg, only about 5mm clearance.

I send off the auto cad file today to the place that has the water jet cutter. They have a minimum charge of E150 so I got 3 sets of flanges cut out of 12mm 316L for E170 so thats not too bad.

I'll do my own first and see how I get on, I'll order my pipe next week.

Also the p90 head has square ports so gonna have to try make a square out of a circle

This is going to be a very interestng thread indeed, plenty of pics of the progress please, also looks like it will be done in true Jay style (you don't hang about do you matey) I'll get the measurements to you tomorrow.

 

[jay28]

Its going to be a few weeks before I get a chance to start it, But I'll have all the bits and bobs ready for action.

Yeah a few measurements would be good, of you can hold your manifold flange up against a flat wall, then measure to the center of each collector off the wall.

Also measure from the center of the flange to the start of each collector horizontally if you get me?

Also a measurement on the length of primaries, they should be around 28" afaik

Also pictures looking straight in, from above, infront , behind and below if you can

That should be enough to get a pretty good copy

 

[samuri-240]

Just another thought Jay I am 99.9% sure the nismo I have is a lhd version as nearly all of them are, the pipework has to be formed to let the steering through, I read somewhere there is a rhd version, a member on the forum has both, if I remember correctly the rhd one is quite different. Just something to add to the mix. :lol:My thoughts are if I had the skills & going to all that trouble would make the rhd version for a rhd car .

 

[jay28]

I know what you mean but I'll have a hell of a job finding a rhd one to get measurements off.

I presume the lhd manifold performs just as well as the rhd one?

 

[samuri-240]

I know what you mean but I'll have a hell of a job finding a rhd one to get measurements off.

I presume the lhd manifold performs just as well as the rhd one?

We don't know yet do we ? think the guy who has them it going to fit both & see what the difference is, can't remember who it was, was it sylve or something lke that, I,m sure he also uploaded some pics of the rhd one on here somewhere.

 

[jay28]

Found these pics that Sylv1 posted on a different thread, he said its a jdm Nismo, that means its for a rhd then right? It actually looks alot less complicated than the lhd version.

They dont look like equal length primaries either.

 

[Ian Patmore]

Good Jay. Had a look at the good book "How to modify your Datsun/Nissan OHC engine" by Frank Honsowetz, and for "wild street engines", 1 1/2 to 1 5/8 is recommended for header primaries. This is for both the 4 and 6 pot L series engines. As most well modified z engines here fit into the "wild street engines" (or lower spec.), no point going bigger. If you don't have the book Jay, worth a read.

Yes, the JDM cars were RHD. Not many people here in the UK have seen, let alone run a JDM Nismo header, and if you want to try something a bit different, give it a whirl. Interested to see how things go.

Cheers
Ian

 

[jay28]

Thanks Ian,

Yes the 1 5/8 primaries are the way to go, Have the "How to modify you datsun engine" book, well used to have, I gave that book, a book on tuning weber carbs and Haynes manual to a guy and never got them back, I must hunt him down.

Si I take it the last pics I posted are that of the JDM Nismo manifold?

Do the primaries look equal length on that, to me they dont. If primaries are not exactly equal length how does this effect bhp?

 

[tel240z]

I do like the smooth bends coming from the head flange i always thought that most of the manifolds seem to have a tight bend almost 90 degrees from the head here's some pics of mine i will let u guess what it is

 

[SeanDezart]

Pace Thrustmaster

Round ports.........to go on a square ported block ?

 

[tel240z]

Pace Thrustmaster

Round ports.........to go on a square ported block ?

Very good Sean im impressed.


Are you asking, fishing or knocking ? anyhow 3 and 4 exhaust ports on the manifold may be square

 

[SeanDezart]

I thought that they should all be square ? Sure that this isn't for an N47 head ? How much are they from the States then ?

 

[tel240z]

well Sean, when i had a little chat with the man from the states this is indeed the one for the square port head, the 2 centre ports are in fact square, the rest are round but are big enough to engulf the smaller square ports on the head, see poicture of used gasket

cost $240 $150 shipping £30 tax i bought this $2 to the £

just for the record 1" 5/8" primarys