Turbo’ing a NA engine

[M.C.]

I know this isn’t a Clio, but I’d appreciate picking your brains anyway.

A friend has asked me to build them a turbo engine for there Nova, I’m going to do it, but If I do, I want to make it powerful and reliable. To do this I have a few questions.

I had a look at two Turbo’d (previously normally aspirated) 1.6 8v Nova’s over the weekend. Neither could run high boost, and they were both setup differently. The two ways people approach this are different. The bodge job is using a plate and two head gaskets to lower the compression. The other way is to use low compression pistons. I have worked out that if I use a 1.6 head and a 1.3 bottom end, I can drop the compression to 8.1:1 Is this low enough?

One of the the cars increased fuel on boost by running a fuel pressure regulator plumbed to the pressure side of the turbo. The other also had this, but also had a pressure activated reed micro switch that appeared to be wired via the throttle position sensor. Is this needed, and how does it work?

The final question I have is related to ignition. The only reason I can see that the engine using low comp pistons wasn’t working is the ignition. The setup seemed unchanged from normally aspirated. I thought that the ignition had to be retarded on higher boost. Is this correct, and if so how much? Would it be enough to disable the mechanical advance, and if not, what do I have to do to solve this problem.

Both cars were quite fast, running about 15.5 1/4’s but were limited to 9 or 10psi or they would blow a gasket or crack a piston. There was nothing else done to them and they were using the standard ECU

Any help would be appreciated.

M.C.

 

[M.C.]

Sorry, just realised this is in the wrong forum!

M.C.

 

[Captain Slarty]

A friend has asked me to build them a turbo engine for there Nova, I’m going to do it, but If I do, I want to make it powerful and reliable. To do this I have a few questions.

I had a look at two Turbo’d (previously normally aspirated) 1.6 8v Nova’s over the weekend. Neither could run high boost, and they were both setup differently. The two ways people approach this are different. The bodge job is using a plate and two head gaskets to lower the compression. The other way is to use low compression pistons. I have worked out that if I use a 1.6 head and a 1.3 bottom end, I can drop the compression to 8.1:1 Is this low enough?

Compression ratio drop is needed to avoid detonation at load, the dynamic compression ratio will go way up on boost. It is difficult to say the max cr static you can use as its all depended on engine design

One of the the cars increased fuel on boost by running a fuel pressure regulator plumbed to the pressure side of the turbo. The other also had this, but also had a pressure activated reed micro switch that appeared to be wired via the throttle position sensor. Is this needed, and how does it work?

very crude - both of them, and pretty dangerous as far as engine life is concerned.. you not only need extra fuel, but have to alter the fueling - quite dramatically - to compensate for differences in air temperature

The final question I have is related to ignition. The only reason I can see that the engine using low comp pistons wasn’t working is the ignition. The setup seemed unchanged from normally aspirated. I thought that the ignition had to be retarded on higher boost. Is this correct, and if so how much? Would it be enough to disable the mechanical advance, and if not, what do I have to do to solve this problem.

the ignition will need retarding to some extent on boost to prevent detonation !.. you cannot do this effectively with a mechanical advance apart from adding a boost pusher plate - effectively a vacuum advance module in reverse - as well as the existing vacuum module.. as the boost comes on the ignition is retarded .. still crude though. The best way is to mod the ecu if possible

Both cars were quite fast, running about 15.5 1/4’s but were limited to 9 or 10psi or they would blow a gasket or crack a piston. There was nothing else done to them and they were using the standard ECU

Any help would be appreciated.

they are both fairly typical of some of the crude, and amateurish attempts at turbo charging that are doing the rounds, without temp compensation, sensible cr and piston design, fuel supply control and ignition mods, the problems they suffer are typical.

It is possible to buy an aftermarket electronic fuel controller for an extra injector in the inlet tract, and a boost r****d ignition unit. With careful setting up on the rollers and forged pistons / strong bottom end, the results should be reasonable

Joe

 

[M.C.]

Joe,

How are you getting around these issues on your 172 engine?

Thankyou for the advice.

MC

 

[Nick Read]

Would it not be a good idea to run the whole setup on a mappable ECU, Lumenition or something? Surely this could control fuelling on boost etc, hooking up the fuel regulator to the boost is pretty hit and miss, although admittedly without using electronic control there arent many options.

Regarding the ignition r****d on boost, this can be easily solved for £100 (although no doubt Joe can give you a circuit diagram that you can lash up using £5 of parts from Maplin!) - I run a Micro Dynamics EMS6 Boost r****d module. Its basically designed for turbo conversions and boost upgrades. Hook it up to the coil and a boost pressure switch, and it will r****d the ignition by between 0.5 and 2.5 degrees per 1000 rpm. When the boost reaches whatever pressure you have decided on, the switch will activate the unit and pull the timing.

 

[Captain Slarty]

Hi Guys,

MC, if you search back throught his forum on my posts, there are several that discus these issues.

Nick, yes, you are absolutely spot on !.

On my turbo conversion, I dont intend using aftermarket boost r****d or fueling at the moment.

It is, as you say, preferable to utilise a full aftermarket engine management system, DTA, Lumi, WA etc etc..

but.......

The 172, as is common with most modern vehicles, uses the ecu for more than just engine management - ie - air con - trip computer etc, it needs to be left in the car and the race ecu added alongside.

What I intend to do is look at the possibility of modifying the existing ecu to cope.

basically - with increased fuel pressure and larger injectors that can cope with full flow requirements.

I am looking at, firstly, reading the existing flash eeprom from the ecu - I have a spare on the bench now running parsers on the data to locate tables, then inserting a realtime rom emulator in place of the existing rom (chip) this will all be set up on the rollers. and, the side benefit is .. the ability to then program 172 ecus for any engine mods via the serial port under the ashtray ..

Wish me luck.. its gonna be rough.. its gonna be tough lol but we have the technology..

Joe..

 

[Alex M]

Just out of curiousity, with the turbo 172 engine, what kinda inlet pressure are you aiming for.

Reason I ask, and I know it might be sin to ask this here, as it concerns an RS Turbo my mate is screwing around with.

The shell is a dog but it was running great, and though he would get it to have as a toy.

A new uprated actuater, samco hoses, a bleed valve made from a washing machine hose and gas tap, and a heavy duty dump valve, along with an analogue guage have been added, along with a boost controller.

Got the car going and played about with it. The tap he is using is a bit vague, but we found some reliable power running 14psi, tried 18psi (maximum achievable with his set up) but numerous probs appeared here: intercooler pipe blowing off and the obvious detonation that occurs here given the pressure and the lack of fuel. The head gasket has now unsurprisingly blown, and taking the head off reveals he has got lucky and there has been no damage to the pistons. He does not want to fork out for expensive non standard pistons.

Heres the question, could we use an extra injector and controller to sort the fuel. And if we replaced the standard intercooler with a monster one I have found off a lorry, could he get away with running such high boost. Otherwise could it be worth looking at perhaps a water injection system to cool the charge and prevent melting the standard pistons. Or is he just going to have to spend money to reliably run this.

Cheers


Alex M

 

[Captain Slarty]

yes, an extra injector could work..

preferably with an electronic controller.. also a boost r****d unit will be needed..

that should help the detonation problems.

the larger intercooler willhelp to lower the induction temps and allow higher boost too.

water injection is problematic.. better to avoid it really on a fairly crude setup ..

the gasket probably failed due to pressure rise on detonation... sort that, and it should help.

Joe. ps.. love the boost variable valve.. sounds like one of mine lol !

 

[Captain Slarty]

sorry, also re the original paragraph re 172 boost.. looking at about 14-16 psi initially, then 20-24 later


Joe.

 

[Nick Read]

Alex have you thought of running a chargecooler instead of an intercooler? Water injection could be a cheap fix though.

 

[Captain Slarty]

I agree.... to a point

the only problem I have with a water rig is knowing that

a, there is water

b, that it is circulating...

most rigs are using cheap pumps and no software monitoring m8..

if ya get a good un.. great.. but you need to be alerted to any of the above !.

Joe..

 

[Master Chief]

About the extra injector.
Here in Israel some of the most modded cars use and extra 4 injectors setup conected to a MF2 - wich is a device that will electronicly operate the extra injectors according to manifold pressure.
My friend just added this setup to his 1.8 Golf gti, togheter with a T3/4 turbo upgrade shold have about 320 BHP at 1.5BAR Boost.

Captain, how are you ?
Any news on the Turbo Kit ?

Thanks!

 

[Alex M]

Cool, got a monster intercooler from a DAF lorry which we are going to try and get to fit somewhere in the air flow, a charge cooler would be more compact but also more hassle. He wasnt that keen on splashing out on it, but we did get a mint 1.3 pop plus shell last night for £30 which I reckon he is going to throw all the running gear into. This means he might be more likely to spend a little, so I will suggest an injector and controller. It is the mechanical bosch injection, so could a capri v6 fuel pump be used to simply supply more fuel to the stock injectors or is not quite as simple as that. Glad you like tap although it is hard to set consistently. Anyway cheers for your help guys will let u know what route we take.

14psi on the clio, is it going to be all standard internals, or is anything getting replaced. No 172s up my way so am keen to see one first hand, they sound rapid although prefer shape of mark1s. A turbo would be cool though.

Alex M

 

[Alex M]

While on subject of escorts, You would not believe the rot and filler in the roof of this RS, and the nick of the spare wheel well, and under back seats. I forgot how rotten Fords off that vintage can get. And this is a car that had been looked after (F plate) which is why running gear was so good, unbelievable.

Alex M

 

[sandys]

Chargecoolers arent much of a problem, I have had one on my Coupe for about a year managed to pick it up secondhand with an uprated intercooler and pump etc for £400 baragin if you ask me, needs no more maintenance than to check if you have water and its working, which you do whilst doing your routine weekly checks on things like oil and tyre pressures, it should never lose any water, they work quite well.

You can find the odd chargecooler in the scrappy if you are lucky a few cars have them standard fit, same as you have done with your intercooler

If the water fails to circulate sure could be a problem but you would notice and drop in performance due to the heat the water jacket would get to but cant imagine you would experience a problem unless you were idling where you dont have the air flow over the engine bay.

Cheers

 

[Captain Slarty]

yep, but the boost isnt there on idle..

So, that wont be a concern..

Alex, Forged 8.5:1 pistons (Custom) are going into the unit, along with the f4r turbo crank.. std rods, and a completely fdifferent inlet manifod and exhaust (Again from the f4r turbo Aventime / Vel Satis unit.

Joe.

 

[sandys]

Indeed Capt but it does depends on location mine is right next to the engine (basically only place it would fit) heat soak from the engine mean that at idle the water would end up boiling as the jacket rather than cooling will act as a nice hot radiator. with more under bonnet space youll be able to find a better location.

heres a pic if it works

http://www.alexander.smith1.btinternet.co.uk/mycar/DSCF0058.JPG" NOSAVE height=480 width=640>

 

[sandys]

its the tiny silver thing next to the engine

 

[sandys]

of course I mean there would be heat soak if it didnt circulate the water, when functioning normal the thing is bloody cold quite a contrast to the engine next to it.

 

[Captain Slarty]

Nice shot..

it is worth adding some heat reflective ali bubble plate to the outer of the exchanger, that would help soak m8 ..

the water is then free to offer its excellent thermal transfer (aint got the books at hand, but I think its something like 200:1 in favour of H20..

the other benefit is the smaller water to air dissipation radiator needed.

As said by both of us.. if you can sort out the flow reliably, then its a better solution.
Joe.