172 Head Work - BHP Gains/How much

[Simon]

What do you reckon the possible BHP gains would be from getting the head and inlet/exhaust manifolds gas flowed/ported on the 172 and sticking with the std. cams? in addition then take into account, decat, full stainless steel exhaust, viper and ECU remap - what would be the bhp gains then?

Who do you reckon could do a good job of the head work and how much to have it done?

Cheers,

Simon

 

[helfire]

I looked into doing the same and was told go throttle boddies as they would provide better power than modding the head. But would be nice to know what the mods would provide aswell.

 

[geoff_clio182]

Ive been told not to bother with head work and just go for throttle bodies as this is where real gains can be made.

 

[coolspot007007]

I think i heard Renault did a decent job flow wise with the head to kick off with, so aint much gains to be had.

 

[Jellyhead]

I was told exactly the same as Geoff from a well respected source.... same goes for cams to a certain degree.

 

[BenR]

well, its all relative.....

for an OE head, thats just cast.....its brilliant. but thats not to say you cant do things to it to provide more power.

the real gain though is from eitehr modding the inlet manifold and throttle body as these are teh main restrictions.....i say restrictions as it limits power, but does provide the torque. the MK1 TB is actually larger than teh MK2, but teh MK2s design allows it to be smaller (better gas velocity) and hand ober more torque but with the same top end power. the MK2 need the incresed torque as its heavier (shhhh, MK 2 owners dont liek that, but im one too).

anyway, on our cup racer, we are modding it to enter either super production or ghia in SE asia. with a set of indivicual throttle bodies alone we achieved 215bhp @ 7700rpm.

now if we were to work on teh head (not allowed) some mild yet clever work would reward us with a few ponies, in teh regoin of probably a max of 20bhp extra in full race trim.

on teh road, if you can afford it, go for TBs alone as this will give massive gains for your buck. if not, work teh inlet manifold and TB as a first as they are crap...well, not crap, but we can do better......

perfection is not mass produced......well, unless you got a chaterham R500..

 

[Simon]

Hi Ben,

What areas would need to be changed on the inlet manifold and the standard TB - is it easy to do?. I guess making these changings would require ecu remap to take into account better breathing?

Cheers,

Simon

 

[BenR]

yup, adjusting the fueling and ignition to suit will be neccesary.

But gains from the TB will be ltd as there is not much you can remove, and teh FBW doesnt help as its a sealed unit.

But basic flowing and matchign of the inlet manifold along with deatailing to the head should reap about as much as much if not more than any filter/exhaust/chip combo.

its all new territory, but with our experience on the clio racer we have....power is easy to get and we are lookig for about 240bhp to match teh focuss and 306s in the SEATCC.........but ut does mean removing teh sequntial and runnig the OE induction setup........with a few cheeky mods.

 

[Simon]

I remember seeing a Japanese firm that did a larger single throttle body for the 172 but it cost loads. Ive got the MK1 throttle body without the FBW.

So if we take the std. 172 inlet manifold. I can probably get one fairly cheap from clio cup racer parts bin.

I know of several specialists round my way that build race engines and do specialist work. I guess I could take it to them and get them to optimise the flow of it and then get em to fit it followed by ECU remap.

Would this be worthwhile doing with the std. throttle body as it is?

What exactly does basic flowing and matching of the inlet manifold entail?

 

[RobFenn]

Jesus. How badly do i want a 172..

 

[BenR]

well, you would really need to get the TB to flow more otherwise any porting behind it in the air path is goin to awste as the TB can max.

That jap one IS expensive!!!!

The inlet manifold.....there is a little you can do to get it sitting exactly flush with the cylinder head, as they are only the slightest bit out. Owrk with teh gasket to make sure it doesnt protrute into the airflow. The work on teh inlet manifold internals......increase plenham volume, taper the ports, enlargen, smooth shape.....etc etc......there is always something you can do.....

but that TB is tiny.....the honda 1.6 civic is about the same size! but dont feel too bad...at least we dont have 206 gtis which haev the the worst TB, inlet arrangement and izing of any GTi i have ever seen...you can gain 30bhp alone by junking it! or getting the 406 (or something, 408, 608 whatever thay are numbered) stuff adapted.

 

[Simon]

Can you think of a larger throttle body from a renault car that would go on and would flow better? Im assuming that the one I have doesnt have any electronic stuff in it and is a mechanical device. I guess there must be companies that manufacture ones similar to mine.

Will see what I can dig out from the internet. Thanks for your advice.

 

[Simon]

From a previous postabout the larger throttle body.

Inner diameter of the inlet is 70mm, which I think is about 13mm bigger than standard.

Here is a picture of the larger throttle body - between £700 and £800 - a CON.

http://www.g-shinwa.co.jp/shopping/product/0034/pic/photo_1.jpg

 

[Simon172]

isnt it on integra Type Rs where you can sand off/shave off the screws so it gives better flow on the butterfly?

 

[Simon172]

also - can you shoe-horn on the mk.2 throttle body to a mk.1? or would you have to alter it to FBW and change the ECU etc etc etc?

 

[Simon]

Good questions.

I believe the MK2 throttle body is slightly smaller than the MK1?

If you look at both throttle bodies you will notice that they both have an area jutting out on the left hand side. A connector plugs in here that allows the engine management to monitor how far open it is.

It might be possible to machine the existing one putting a bigger butterfly in or looking at other throttle bodies in the renault line up and using one of those. Perhaps the throttle body from a Laguna V6 could be used? need to be able to see one and compare ! ANyone know?

 

[orlandopaulo]

does anyone know any site with any throttle bodys kit for clio172Mk2??..

tell me.. filter + reprograming ecu= extra 10-15hp

now...13mm larger throttle body + filter + reprograming ecu = ??hp extra??(any ideia)

 

[Simon]

Very difficult to give figures for this.

What I have also done is get my car rolling roaded at the same place after having any new mods. done but even then you will get differences. e.g. tyre pressure, temperature, rolling road upgraded with new software. Only way is to start with a std. car and then add mods. one by one on the same session seeing what the results are each time you add. a mod. on and then you can compare incrementally !

Im currently running 180 bhp (rolling road estimated) with cold air induction kit, decat pipe and full stainless steel exhaust system. With ECU reprogram, larger throttle body and ported inlet manifold plus timing modifications I would hope to hit 190 bhp maybe less/more. Im no expert at this stuff but when you read into it and speak to tuners/etc a lot of it seems to make sense. Sounds like the std. head and cams are very good and I personally wouldnt bother now doing anything to them after speaking to various people - although gains would be had - I just personally cant afford to invest in having head/cam work.

 

[BenR]

I measured the sized and posted the difs a while ago.........not much.

outer Dia is teh same but inner on teh MK2 is smaller and tapered.

there is no point changing to MK2 TB, and there is not enough metal on teh MK1 to machine out, but small improvements ot the spindle can be made as its HUGE!

also, the potentiometer you mentioned cannot be moved.

oh, and you can flatten the spindle on any TB, but its easier to go larger as in most cases its done to meet regulations on TB size during competiton.

 

[Simon]

Hopefully getting my hands on an Intake Manifold and Throttle Body from a MK1 and take a look with my tuning friend to see what can be done if anything. Agree with you ben about there not being much material.

Is there any way of machine the bottom end out and then putting a larger flange on top with a bigger butterfly?

Have you seen the throttle body from a Languna V6? if so you reckon this might go on?

 

[BenR]

i have not directly compared the V6 item, but making an adaptor plate should not be hard at all...its only 4 bolts

as for machining, i dont understant what you mean. machine the bottom end?

even if you do make the part after the throttle plate larger, the same size TB opening will be the same restriction.

there really is not much you can do the the MK1 TB, and i wouldnt fiddle with a MK2 item....simplest is to get another to fit.

 

[Simon]

Dont worry probably confusing myself having not fully looked at my throttle body physically. I will take a look in the daylight and then see if what I was thinking is still possible and if so will then try to reexplain it.

So looks like the best option is to try and source a larger throttle body from hopefully the Renault range to fit, perhaps laguna v6.

Im correct in stating that what ever throttle body I was to use it must cater for the Throttle Potentiometer. Do you know if there is compatability between the Renault vehicles and across other manufacturers with this in mind.

E.g. I can plug into it and the ECU works.

I think I will contact some companies as well that make single throttle bodies and see what they have to say.

By the way found out the cost today for a replacement inlet manifold and throttle body for the 172 phase 1 - not cheap.

Around £430ish and £185ish plus vat !

 

[BenR]

uh huh!

well, i would hazard a guess that ptentiometers from most of the current Renault cars will be the same.

and yes you must run it otherwise the ECU doesnt know throttle position.

So, check connectors on the potentiometer on both TBs you look at. oh,and your cars a MK1 aint it.....cause if its a MK2 your gonna have to fiddle with FBW or get another TB which uses FBW.

im not sure about intor manufacturer sharing.......

talk to jenvey dynamics, they make loads of kit and will help you out.