16v VS 8v turbo?

[miamibluebaby]

Right at the momnet i am building a 1.4 8v turbo engine,

with 106 xsi head, S1 rallye inlet, dta S40 managment, LC-1 wideband, catcams turbo cam. etc a decent spec to start with.

In the near future i will be looking into a 1.6 bottome end and forged lowcomp pistons, also a better flowing Mani and larger turbo


My question is, why do i only ever see 300+ bhp 16v engines??? is its as simple as the 8v cannot offer enough flow to reach that sort of power, are there limitations with valve size etc?? in theory i presume that 300+bhp is achievable in 8v format. Is it any easier with 16valves. just dont know how finacialy viable it is plowing a shed load of money into getting headwork done, internals, spec up the inlet etc..... to be left thinking i wish i had 8 more little bits of metal in there....

Also how usable really is that extra power??

[axsaxoman]

It is technicaly possible to get 300 from an 8v ,BUT yes its alot easier + cheaper to di with a 16v
so in answer to your question --yes go 16v
I would also suggest you think about how you intend to get 300+ bhp on the road ,especially with a turbo ,which by its nature ,suddenly spools up and breaks traction ,then you back off ,boost colllapses --on the throttle again ,wait fro the lag then off you go again.
you cannot use 300 bhp at 4k on a FWD car ,so either you are going to spend alot of money + time on setting up boost control to make it user fiendly ,to never be able to flatten throttle till your over 80mph in third gear

I could be wrong but i have not yet to see a vnt electornic control turbo on a saxo -- cos nobody wants to spend the money it would cost for the electronics / traction control system to make it a user friendly drive.
think carefuly about how much REAL bhp you want.
I have nothing against turbo conversions ,but it is the above reasons and other heat related issues why I have concentrated on s/c -- it is progressive and more user fiendly to both the driver and the transmission.

[dannygti]

there is a 106 rallye on 106 owners with a claimed figure of around 450bhp. hes from greece and its a tidy car.


http://www.106owners.co.uk/forums/showthread.php?t=131105

[saxokid100]

Go down the 16v road..........

[atspeedracing]

a lot of it comes down to people simply not appreciating how much power that actually is... 300bhp is just a number until you experience it... only then can you respect it.

i find a lot of customers just wanting cars for power figures, not actually suited to what they want the car for...

its the same rule in all parts of tuning.. people always choose a cam 2 steps up from the one they actually need, or a turbo thats 2 sizes too big! lol.

[samueljonburgess]

i think the route your goin down is good :) better to break the chain :)

[Sophia_Bush]

for a road I think 170/200bhp is enough well for me it is anyway

The spec I amprobably doing is very basic but will be enough to have some fun

[axsaxoman]

there is a 106 rallye on 106 owners with a claimed figure of around 450bhp. hes from greece and its a tidy car.


http://www.106owners.co.uk/forums/showthread.php?t=131105

yes I have seen all these claimed figures and whilst it is technically possible I find them very hard to bleive --where is the monster intercooler ,
and at 2bar of boost it will need a big bugger .
It may show 450 for 5secs on dyno if its stone cold ,but hold it there for 15secs and see what power it shows --will be at least 100 less .
it is impossible to get 450 bhp on to the road on a fwd ,it would wheelspin in every gear at any time .
it could be real ,but the fact he is saying he needs a bigger turbo tells me the dyno is not accurate --yes it will be quick ,,
but actual bhp figure -- no .
ask him what clutch he is using and what are size of his injectors and the duration of them at full power+ fuel pressure and i will sonn tell you if its real
get him to post the dyno graph-

[dannygti]

yes I have seen all these claimed figures and whilst it is technically possible I find them very hard to bleive --where is the monster intercooler ,
and at 2bar of boost it will need a big bugger .
It may show 450 for 5secs on dyno if its stone cold ,but hold it there for 15secs and see what power it shows --will be at least 100 less .
it is impossible to get 450 bhp on to the road on a fwd ,it would wheelspin in every gear at any time .
it could be real ,but the fact he is saying he needs a bigger turbo tells me the dyno is not accurate --yes it will be quick ,,
but actual bhp figure -- no .
ask him what clutch he is using and what are size of his injectors and the duration of them at full power+ fuel pressure and i will sonn tell you if its real
get him to post the dyno graph-


i 100% agree john.


it seems to me greek power figures are much different to the ones over here.
big hp figures will only be useful over 100mph...
ive driven a 400bhp westfield that weighs 550kgs but from 0-100 it slower than a 200hp car.

also agree with colin, people will have the bigger turbo or the next step up duration cam because that peak figure might be better, where as 99% of people will be better of going for a more rounded spec.

[AXracing]

My question is, why do i only ever see 300+ bhp 16v engines???

Simple answer is that it costs a hell of a lot to get a usable 300bhp saxo. So the saving on buying a VTR over a VTS is insignificant. So most will just start with the VTS.

[tweeqd]

16v's are GAY full stop
people chase power figures with turbos and dont make a car thats driveable

if you look at the 1/4 mile table on SSC for boosted engines no 2 is an 8v ;)

[WestyVTR]

16v's are GAY full stop
people chase power figures with turbos and dont make a car thats driveable

if you look at the 1/4 mile table on SSC for boosted engines no 2 is an 8v ;)


8v love right here on sax-p :clapping::panic: john wouldnt agree lol

[axsaxoman]

not so I used to have a vtr s/c demo car -- it was a far better everyday car than the 16v .
7psi -gave 145 @ wheels totally std internals would rev out to limter in5th no problem --uphill.
very underrated the 8v is --ideal place to start with boost ,as all the expensive bits will transfer to a 16v later if you wish .
I have been tempted at times to build a 1800- stroker 8v ,+s/c.keep revs to 7 k max --mega torquey every day car

[axsaxoman]

16v's are GAY full stop
people chase power figures with turbos and dont make a car thats driveable

if you look at the 1/4 mile table on SSC for boosted engines no 2 is an 8v ;)

tool the s.c demo vtr to york once -- very suprised to end up in top ten run off -- got totally bladdered like -- just shows how qucik even a vtr with 7psi can be

[WestyVTR]

hmm want to use my car for that project... lol

8v stroker kit + s/c + TBs ... dream land!!

ive spent close to 2k getting it back on the road... you could finish her off with a polish... :-)

[tweeqd]

tool the s.c demo vtr to york once -- very suprised to end up in top ten run off -- got totally bladdered like -- just shows how qucik even a vtr with 7psi can be

it suprises people when they find out mine an 8v, i was running 13 sec 1/4 and that was with a comp ratio of 7.1, cant wait to try the new CR witn the nitrous and biggere turbo

[atspeedracing]

we are currently working on a customers 1.8 long stroke turbo 16v TU, should show some interesting results.

[tweeqd]

cool, wheel spin all the way down the 1/4 not just the 1st half :P

[WestyVTR]

imagine the cost on tyres and the petrol.... its just not practicle is it dear :-s

[axsaxoman]

we are currently working on a customers 1.8 long stroke turbo 16v TU, should show some interesting results.
hope you are also working on some serious traction control at same time.LOL

[Cammy]

What performance gains do the stroker kits give alone for the extra 318cc they give?

Because I'm aiming for 130bhp+ N/A 8v before I consider going turbo

[axsaxoman]

What performance gains do the stroker kits give alone for the extra 318cc they give?

Because I'm aiming for 130bhp+ N/A 8v before I consider going turbo
If you go for a 30% + increase with current engine before turboing ,then some of the bits you fit will be not right for the turbo conversion ,like the cam + 4-1 ex manifold ,so my advice is plot out where you want to be with the turbo and only buy parts once.
diferent if you were going s/c you would need a decent ex manifld + maybe same cam would do,
but until you put a bhp figure on finished project no point in buying anything to get your 130+
what will a stroker kit give you --guess?-- 20%.

[AXracing]

What performance gains do the stroker kits give alone for the extra 318cc they give?

Not as much as you may think as your still restricted with breathing. Not only are you using the same head but your also trying to cram more air though it.

Because I'm aiming for 130bhp+ N/A 8v before I consider going turbo

A lot of what you would do to tune a normally aspirated engine is very different or even the opposite of what you would do to turbo it. For example like John said the exhaust manifold would be totally different. People lower the compression on a turbo engine yet increase it on the normally aspirated one. Also the optimum cam profile would be significantly different.

[axsaxoman]

my fault -my post no totally clear --no point in going 1800 cc until you fit larger valves and VERY serious porting job to increase the air flow through the engine.


we took the 1294 engine as far as we could and limiting factor was size of ex ports --I cut into water jacket more than once,which meant then welding it all back up once port was correct size+ shape --the answer was to machine ALL the port out + the ex valve seat area and weld in larger runners and replace the valve seats.
I am not saying you would need to go that far to make 1800 8v perform very well ,but that would be the ultimate answer
we never got round to it

[blackie_2k5]

8v ftw, 170 will see me happy, totally dpeneds on what the end result is for, mines for a fast road fun toy, with occasianal track use, my goal is 200 but even that is alot for my needs, any more and itd be pretty useless for both my requirements, im speccing it for good usable fun power without mega costs. some good info in this thread already.

[miamibluebaby]

Yes, good advice from all areas here, at the end of the day it needs to be fun, and to a point practical, i think my best option is to stay 8v, carry out the work on the engine gradually, eventualy spec up internals and turbo and find the balance with usability