Help with HP increases in 2.0 Fuego engine

GRAHAM WALLIS said:
4mm? what is the compression ratio?
Click to expand...
I honestly can't remember. But the pistons originally sat about 4mm down the bore at TDC, and the aim was to get them to the top of the bore. The compression ratio is dependent on only the combustion chamber volume and head gasket thickness.

We did have to flycut the pistons, and it needed premium fuel to prevent pinging.
 
dacia4x4 said:
wasn,t the 2.2 about 6mm taller in block to allow for longer stroke.crankshaft a lot bigger as well in mains and big ends.did you use standard 2.2conrods?…jim
Click to expand...
Rods, pistons, and liners were all standard. I'm not sure about the differences between the 2.0 and 2.2 blocks.
 
Staying with 2L, the R20 had higher significantly higher compression standard than the Fuego, which I believe was done through pistons only. French Car Care in East Brisbane have an old Fuego race car that has one of the 12 valve heads fitted, and might be available. I believe Denis may have brought in other 12V heads at the time, but many years ago.

From what I remember the ports and valve sizes (44mm inlet as I remember) on the Fuego head were not bad. The cam and compression could do with an upgrade, which will give you the biggest gains for the least drama, given you already have sidedrafts. An adjustable cam pulley may be useful whilst tuning on the dyno. The original cast headers and two into one pipe after that worked OK as well. The flywheel could do with a haircut to reduce the weight, particularly in a light car.
 
My course of action in a misspent youth was to find a similar design engine to what I was working with being used in something a whole lot more interesting and basically copy what the developers did - big benefit was off the shelf bits 'n pieces and very little hair pulling... :)
Stuff like advance curves for high compression and cams with big overlap are not a job for the backyarder.... Done with their design I got a street car that idled nicely but went like stink - but, typically for the age group, I didn't bother with swapping out the teensy drum brakes, so it didn't stop too well.... :(
Bob
 
Demannu said:
I honestly can't remember. But the pistons originally sat about 4mm down the bore at TDC, and the aim was to get them to the top of the bore. The compression ratio is dependent on only the combustion chamber volume and head gasket thickness.

We did have to flycut the pistons, and it needed premium fuel to prevent pinging.
Click to expand...
That is interesting.
it has been a while now since I messed with these donks but I seem to remember a standard Renault 2.0 piston sat flush with the top of the liner.
i looked through my photos but couldn’t find any of the headless lower end.

as far as the differences between the 2.0 and 2.2. The 2.2 is a heavyweight by comparison.
crank and Conrods are much beefier. 2.0 Conrods look dinky compared to the 2.2
a 2.0 big end will fit through the liner whereas a 2.2 wont so the only way to insert a 2.2 piston is from below.
 
Having said that I did modify a 2.2 by offset grinding the crank, used Nissan L20 rods and 504 pistons, to give longer stroke and lighter rods. Went well with a mild cam. Manage to overheat it when a heater hose blew. Sold it but the buyer has yet to do anything with it after 10 years. Now have another 505 but sticking with the XN as it has a much better spread of torque than the Douvrin (even in standard form the 505 GTi only works from 3500 rpm) although the light weight of the Douvrin gives a handling advantage.
 
jo proffi said:
it has been a while now since I messed with these donks but I seem to remember a standard Renault 2.0 piston sat flush with the top of the liner.
Click to expand...
Bugger, I guess that rules out my suggestion for the OP's motor.

I remember at the time being baffled when looking at the 2.2 by why they would design an engine with such an inefficient combustion chamber setup - no squish/quench at all. I assumed it was for emissions.

This thread has got me excited... I need to find something to put the hot 2.2 into. It's been sitting in the corner of the shed for many years now, looking very lonely!
 
;) all this covid induced excitement !!, now we older froggers would support a "wipe off five" or even 10 years of aging :ROFLMAO: as we recognise age kills, and it would compensate for the various inconveniences navigated in the last two years... Just a thought bubble, :rolleyes: but dear to the heart...good thread.

Ken
 
Demannu said:
Bugger, I guess that rules out my suggestion for the OP's motor.

I remember at the time being baffled when looking at the 2.2 by why they would design an engine with such an inefficient combustion chamber setup - no squish/quench at all. I assumed it was for emissions.

This thread has got me excited... I need to find something to put the hot 2.2 into. It's been sitting in the corner of the shed for many years now, looking very lonely!
Click to expand...
Clearly you need to mount it behind a race seat and make yourself a little clubman :D
 
All this Fuego talk has me day dreaming about the largely stripped shell I have at the farm and putting a supercharged Laguna V6 drivetrain behind the seats..
 
We all know it's fun to increase HP. However, the reality is the same money spent on brakes, tyres, suspension and driver training will improve lap times more effectively. Sorry, I hate to be a killjoy.
 
i recall reading that jack Brabham had to convince the engineers at Honda who provided his F2 engines that they were racing cars not dynos ,and that an engine with a broad torque curve ,produced faster times out of corners and gave the driver more time to drive, when not having to continually change gears to keep it on the boil .i agree horsepower isn't everything ,
 
Yeah, but it's fun! :party:

But OP, I'd love to see images of this car of yours. I love the idea of recycling the simple box and engine and making an open wheeler out of it :)

Come to think of it, why aren't kids doing this with modern Subaru drive trains?
 
Demannu said:
I honestly can't remember. But the pistons originally sat about 4mm down the bore at TDC, and the aim was to get them to the top of the bore. The compression ratio is dependent on only the combustion chamber volume and head gasket thickness.

We did have to flycut the pistons, and it needed premium fuel to prevent pinging.
Click to expand...
I did some maths on the engine based on the standard 8.8 to 1 comp ratio.
With the stock 88mm bore I came up with an above piston at TDC volume of 69cc.
541cc + 69cc = 610cc ÷ 8.8= 69cc
4mm of cylinder volume = 24.3cc
New above piston volume = 44.7cc
541cc + 44.7cc = 584.7 ÷ 44.7 = 13.08 to 1 CR

This assumes the same thickness head gasket and doesn't include the unknown volume of the flycuts.

Either way it's pretty high.😁

My brother bought a very quick (already built) 351 Cleveland engine in an XA falcon in the early 80s. Among the specs were 11 to 1 TRW forged pistons. It needed premium fuel and we were always balancing the ignition timing for power with "acceptable" pinging, especially with the cast iron heads.
We freshened it up a couple of years later, and while it was on the engine stand a mate that built race engines stopped by and started asking about the 13.5 to one pistons and what heads were we using?😳😳😳😳😳
Cc'd the 302 heads which had been relieved to stop the pistons hitting them and it worked out at 12.7 to 1. We just put it back together, it went good before, just pinged a bit at full noise.🤷‍♂️
 
My old Standard 10 ran Mini Cooper pistons, which popped up into the gasket space, over bored to 3/16" between the outer bores. It had a CR in the 11.5 zone and didn't ping at all. Naturally, when one wants some definitive data it's all gone, but it was basically set up from a tuning manual produced by Standard-Triumph for those that wanted to race their Spitfires, I recall that the replacement dizzy had no vacuum advance and the mechanical advance was precious little along a straight line graph.
Bob
 
i recall seeing a standard 10 going down Falcon st North Sydney, back in the early 70s that sure didnt move like a standard 10 ,must have been a common mod or maybe it was bob
 
bob said:
My old Standard 10 ran Mini Cooper pistons, which popped up into the gasket space, over bored to 3/16" between the outer bores. It had a CR in the 11.5 zone and didn't ping at all. Naturally, when one wants some definitive data it's all gone, but it was basically set up from a tuning manual produced by Standard-Triumph for those that wanted to race their Spitfires, I recall that the replacement dizzy had no vacuum advance and the mechanical advance was precious little along a straight line graph.
Bob
Click to expand...
CR really is just a theoretical figure based on the assumption of 100% volumetric efficiency.
There are many variables that will effect how an engine will run in the real world.
Chamber design, ignition timing, fuel mixture, fuel quality, cam timing (very long duration cams lose a lot of cylinder pressure in the low to mid range) cylinder head material, vehicle weight, vehicle gearing.
One engine may run fine at 12 to 1 and another might ping at 9 to 1.

I have a supercharged 850cc Reliant Regal. It has a 10.5 to 1 static compression ratio and makes 10 pounds of boost. The corrected compression ratio at sea level at this psi is 17.6 to 1.
However it runs really good, doesn't ping on 95 octane, BUT the entire Reliant engine is very lightweight alloy construction with a good combustion chamber design and the much modded vehicle only weighs 340kg with a 1/2 tank of fuel.🤷‍♂️
The same engine in a 600kg car may well implode.💣

I would suggest if any serious increases in cam timing (with the Renault engine discussed) are considered, it should be accompanied by a significant increase in compression ratio otherwise the low and mid range will suffer dramatically.
 
Nothing flash about the chamber design in Standard/Triumph engines back then, just a simple bathtub with a rather large squish zone. I can't remember the cam timing, but there was bags of overlap, you could feel it was there above about 2000 RPM. Ports were polished etc, bigger valves, double springs.... combustion spaces were all matched for volume. All balanced up it easily ran out over 6000 RPM and was more than a match for the local hot Holden brigade.
Triumph six cylinder engines were the same basic design - the front and back plates fitted both 6 & 4 versions
pugwash said:
i recall seeing a standard 10 going down Falcon st North Sydney, back in the early 70s that sure didnt move like a standard 10 ,must have been a common mod or maybe it was bob
Click to expand...
crikey, another fool.... :)

Bob
 
8 valve Peugeot engines are terrible for pinging on high compression. 9.6 to 1 is the limit for the 205 1.9 on 98, need to carefully adjust the timing. 504 505 pushrod engines have 8.8 to 1 as maximum factory spec. I remember an 1800 504 which pinged terribly on 8.3 to 1 had to fit non projecting plugs (N5 I think) to cure the pinging on 97 leaded. 16v seem happy at 10.8 but with more advanced management.
 
You must log in or register to reply here.
Top