Inlet Manifold Design Theory

[stevec205gti 0]

Firstly, apologies if this is the wrong section, but I thought it was more technical than the General car chat area, and also these kind of topics normally gather up lot's of useful info that can be helpful to lots of people.

 

BAsically, I am hoping to remove the HS2 carbs and ropey distributor of my 1300 MkIV Spitfire and replace it with something ore modern and engineeringly challenging. I have the remains of an XU10 8 valve in the garage and am hoping to hijack the ignition parts and some other sensors from that. Injector wise am guessing injectors out of something like a 1.2 punto will do the trick.

 

My real concerns at the moment are the inlet manifold as this will take some thinking. Below is a rough design I've cobbled together on ProE:-

 

 

It's only going to be something basic, with a single throttle body. The inlet tracts are grouped as pairs as the exhaust manifold wraps around either side and in the middle (no cross flow on this baby ). My biggest questions at the moment are what length inlet tracts to have and what position to hold the injectors at. I'm hoping to do a little porting of the head in line with the official tuners hand book, and maybe a sportier cam in the future.

 

Discuss

[M3Evo 0]

Wahey!

 

Cool project

 

Guess that having a measure of the inlet lengths on the old setup would be a reasonable place to start

 

You gonna ditch the dizzy too?

[jonD6B 0]

What is the reason behind keeping it a single throttle body?

[Dom9 2]

Buy A. Graham Bell's book on 4-stroke engine tuning... All the equations are in there... It takes into account inlet lobe duration and things... Probably a good investment for anyone on here in fact!

 

Looks like a good project...!

[stevec205gti 0]

AT the moment the inlet tracts are the same length as the 2 into 1 section of the current manifold.

 

Yes I will be ditching the dizzy - at the moment it runs a nasty Delco unit which constant has the bob weights etc seizing up, and is very difficult to get parts for (despite having TRGB only 5 minutes up the road!). I'd quite like to ditch the whole oldie worldie setup and get something a bit more reliable - the current setup's got so much play in trying to get any kind of reliable timing out of it's a nightmare!

 

The reason for only having a single throttle body is two fold. The first is it'll be a lot easier for me to make cheaply (and doing this cheaply is a big aim of this project) and secondly the car only kicks out 65bhp anyway so I can't see the percentage gains of having four throttle body set up being worth the cost. I'm not after mega performance out of all this - just a 30 year old car that will run reasonably well over varied weather pootling around the local roads.

[M3Evo 0]

just a 30 year old car that will run reasonably well over varied weather pootling around the local roads.

 

And which starts first time without drama too?

[stevec205gti 0]

LOL - first time might be asking a bit much, but starting on a daily basis would be nice!!!!

[Rob_the_Sparky 9]

Can you not just use a pair of TBs from the 2.5PI? This has 3 pairs of TBs as standard, you may well be able to use a pair of them for this...

[d-9 0]

Is it possible to modify the triumph bodies to take electronic injectors? Ive got some pics of them i'll post up tomorrow, but in the mean time, why not do this instead:

[mfield 20]

Give me a shout if you want anything machine cut

[stevec205gti 0]

Well, i've ordered my book off ebay, and I've been on the Triumph Torque website to see if any of them have a throttle body they can measure up for me (though I expect to get some grief - seems that quite a few of them don't agree with modern day electronic fuel injection!!!). I've also spotted a set on Fleebay for £20...... just hope I can get them measured up before the auction ends!

 

Thanks for the machining offer - I'll give you a shout should I actually progress past the design stage!!!!!

Edited February 18, 2006 by stevec205gti

[stevec205gti 0]

Well, apparently the port spacing is different between the 4pot a 6pot lumps so the PI throttle bodies aren't a direct fit - I still like the idea though so I may nip up to my local triumph place, see if I can get an old knackered one and see if making up a small adapter is feasible.

 

On a side note, the cyclinder head came off a couple of weeks ago, and I got the rest of the engine out this weekend just gone. I think I may have to get a engine crane to put it back in though - picking it straight up and carrying it out by myself was bloomin hard work!

[mfield 20]

picking it straight up and carrying it out by myself was bloomin hard work!

 

 

I bet i was

[M3Evo 0]

remember optimistically thinking that me and miamistu would be able to lift the GT6 engine between us.

 

Think we got about 6 inches and then dropped it

 

Are we not all that is man?!

[Rippthrough 98]

remember optimistically thinking that me and miamistu would be able to lift the GT6 engine between us.

 

Think we got about 6 inches and then dropped it

 

Are we not all that is man?!

 

i dropped mine onto a skateboard and just pushed it under the new chassis. lifted the chassis over it

[Rob_the_Sparky 9]

remember optimistically thinking that me and miamistu would be able to lift the GT6 engine between us.

 

Think we got about 6 inches and then dropped it

 

Are we not all that is man?!

 

Now that is hopeful! Those things weigh an absolute ton.

[stevec205gti 0]

Got sent this off the triumph forum - very useful for anyone doing their own inlet system....

 

 

Inlet PDF