8v boost question

12th September 2015, 19:16

Hi all, am gonna be soperchargering my vtr over the winter, am gonna be using a rotrex gp30 for boost and am gonna use a predator ecu as management, my question is whats the best injectors to run on a 8v and what spark plugs are best to use, my vtr is the cross over silver top metal oil filter type, Am hoping for around 190-200 bhp once mapped etc
Thanks in advance

15th September 2015, 13:16

std vtr is 90bhp --to get 180 is a 100% increase which will require 1 bar of boost --so think hard about using std pistons

15th September 2015, 16:24

Blackie used standard internals on a 230bhp turbo VTR

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15th September 2015, 18:17

There 10 a penny vtr lumps so no issue if it dies, the engine will be stock with 2x 1.6mm headgaskets, my plan is good fuelling, good software, good charger, good map and a good clutch, i know 200 is easy do able. Charger is less harsh then a turbo and 8v turbo when done proper on stock lumps make 200, I wanna see how much u can see from these 8v with stock internals. As said if it last a hour or months a new lump can be had for £50

My research is gti 6 injectors but still unsure on plugs if any 1 on here who has a boosted 8v could share info pls

19th September 2015, 09:07

Sorry to say I have not played with these engines for a very long time but you will wish to go cooler on the plugs. Dont recall the code but You will find tones of old posts on it though. As John pointed out you are pushing the stock engine. At least you will have have good control over ignition and fuelling though don't forget your oil and keeping it cool.

19th September 2015, 09:12

Also do not try to use stock clutch as it will quickly fail and they can really go. I have seen bell housing smashed by exiting clutch bits. The stock diff will also fail. It will be OK if you granny it but if you go for it and keep spinning up wheels it will fail

21st September 2015, 12:12

Quote:

Originally Posted by jbrady72

Blackie used standard internals on a 230bhp turbo VTR

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what a load of bollocks --std engine is 90bhp and no way could you get 230 REAL bhp with std internals --don,t bother to argue you are wrong or someone is lying about the REAL power output .i have been boosting these TU engines for 18 years
I know i,m right and your friend is wrong or jsut lting next your going to tell me he,s using std clutch --If it was possible you would need to run 2 bar of boost to get that from a std spec engine and a lug drive racing clutch as to get that using std cam etc means max power would be at approx 65000rpm so torque would be immense

21st September 2015, 12:31

https://www.youtube.com/watch?v=n1AXDpoJYBQ this guy apparently used AX gt pistons. wouldnt have thought that this engine lasted too long at the pressures listed

21st September 2015, 12:52

Quote:

Originally Posted by axsaxoman

what a load of bollocks --std engine is 90bhp and no way could you get 230 REAL bhp with std internals --don,t bother to argue you are wrong or someone is lying about the REAL power output .i have been boosting these TU engines for 18 years
I know i,m right and your friend is wrong or jsut lting next your going to tell me he,s using std clutch --If it was possible you would need to run 2 bar of boost to get that from a std spec engine and a lug drive racing clutch as to get that using std cam etc means max power would be at approx 65000rpm so torque would be immense

Ok it was 220 at fly, 183 at the wheels.

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21st September 2015, 13:10

1 bar on a gt15 is very different to 1 bar on a gt30...

just saying "1 bar" is meaningless.

21st September 2015, 20:09

Cheera for info, am still researching on plugs, i will be using a helix 4 paddle clutch, hopefully find a diff aswell. I aint fussed about massive bhp, my goal is 200 yes, but if it makes 150 and feels quick ill be happy.

21st September 2015, 20:18

The charer kit is full gmc kit, and ill also be running a oil cooler for engine, the engine will be coming out nov time so ill start a build thread and go from there

22nd September 2015, 08:21

If it's the full GMC kit, I'd maybe listen what Axsaxoman has to say on the matter

22nd September 2015, 12:03

Quote:

Originally Posted by jbrady72

Ok it was 220 at fly, 183 at the wheels.

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power graph makes no sense at at all
it is showing max power at lower rpm than std n/a engine would !!!
and at 1.2 bar of boost which then drops off as rpm climbs showing turbo is at its max capacity ,so will be over spinning at a guess,either that or ex is so restrictive its choking it .
axgt pistons ,which are 75mm not 78.5mm ??? would stick out of the top of the block if fitted to 1.6 rods on a 1.6 block --or is it a cast iron 1360 block??--so its either using shorter rods and/ or pistons are way down the bore --how ever you look at it it is nothing like STANDARD INTERNALS and 218bhp is not 220 bhp OR 230 as in orginal post .
fuelling curve on second graph is all wrong which could also be reason for power dropping off before it should.

24th September 2015, 06:48

Quote:

Originally Posted by Robjohnchapman

Cheera for info, am still researching on plugs, i will be using a helix 4 paddle clutch, hopefully find a diff aswell. I aint fussed about massive bhp, my goal is 200 yes, but if it makes 150 and feels quick ill be happy.

That clutch is a good option. I may be wrong but with plugs ngkbcr8es rings a bell.

With what other people are saying is and is not possible is often down to what people expect from a car. I have seen a lot of power from a standard engine save for two head gaskets. But and its a git but, it was not what you would call relabel. Ok for easy cruising on the road but once you tried to push it you very quickly got good at fixing things. So if its just a fun car you don't have to rely on and are quire happy to destroy you can get away with relatively high powers for a short period. But if your planning to get some good use out of it your worth spending more in the outset.

What you can do is start off with relatively low boost on standard internals. These cars are so light that even for .75 bar they feel fast. Then if you get the bug you can spend a bit more on beefing everything up. Diff, Pistons, Engine mounts .....

Also John at GMC who posted already is very experienced at fitting Rotrex super chargers to the Saxo. As far as I am aware he was the first to do so and has done considerably more such conversions than anyone out there that I know of. So if you require any parts he would be my first port of call.

25th September 2015, 02:11

My point with showing that red turbo Saxo was not to declare it had standard internals but rather what someone has achieved still using oem parts from another, albeit older model but not after market forged items. Who knows how long it lasted or what abuse it took without problems but it looked fun! My view is as the above post, if you want a reliable dependable engine which can be driven hard you need to spend a good wedge of cash along with updating all the other supporting parts

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11th October 2015, 03:28

the dyno was on a rolling road day, i got 5 runs the figures were an average over the 5 it made more power than listed but as expected was ran till the heat started killing the power.. the boost is wrong there was no vac added to it

the AFRs show what they show but the car was road mapped and read level AFR's. the dyno it was ran on is known for showing realistic wheels figures.

the car was not standard, it was a 90bhp black top bottom end with a 90bhp silver top head, ported(heavily by myself), cleaned and polished OE spec valves, rallye inlet (made it worse lol) ported 90bhp throttle body)

it was over spinnning a 250bhp t25 from an s13. the mani and downpipe look not the greatest but were built by someone who did know what they were doing.. not here to argue figure but ive drove and been in plenty fast cars...it did what 400+ cars couldnt