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1290cc HSCC 70s Roadsports racer

Posted: June 24th, 2006, 8:25 pm
by simon-spanner
well, this is my little racer, i've been campaigning on and off for the past couple of seasons
the spec is as follows

stock Fiat sohc bottom end, lightened and balanced
stock cylinder head std valves, ported and polished
stock carb
my own design and fabricated 4-1 stainless steel exhaust mainfold +system

71/4 in. racing clutch
stock gearbox with 4.8-1 final drive

weighs 841kg- class minimum for car
electric water pump

leda adjustable suspension
stock brakes
yoko 032r tyres

the engine develops 120bhp at 9000rpm, although i have in developement another engine (with some GC parts!) that should substantially improve on this figure
i currently shift gear at 9500 rpm zalthough i hav stretched the engine to well in excess of 10000rpm !! with no problems

Currently the car is sitting idle in the workshop, as I am building 2 cars to compete in the Britcar 24hr race at silverstone in sepetember, but i hope to be able to squeeze in a couple more outings this year

Posted: June 25th, 2006, 10:54 am
by sumplug
hi simon.
the power figure is at flywheel i presume? if you are running all stock except a flowed head, you have added 47bhp presuming you started with 73bhp [standard exxie 1300]. now to get the engine to rev to 10k and make the power, you must have altered the carb and cam. are you not getting valve bounce with standard springs?? please tell me the spec simon as iam thinking of building a cinq with a 1300 or 1500 sohc or perhaps a tipo/tempra 1600 sohc. :D

Posted: June 25th, 2006, 4:24 pm
by Guy Croft
Sumplug - Andy, greetings!

a warm welcome to the new GCRE forum, I hope you'll be an active participant and find it worthwhile and interesting too.

Yours very sincerely


Posted: June 25th, 2006, 6:21 pm
by sumplug
hi guy.
thanks for the welcome. will try my best to get involved in your new site. a very exciting future i can see here. :D

Posted: June 26th, 2006, 10:22 am
by simon-spanner
Hi Sump
as you rightly assume the figure is a flywheel figure
the cam is a piper full race cam
you do not want to use this in the road, it has poor torque, and doesnt really get going till over 6Krpm
the carb is modified in so much as it has fully radiused trumpets, and the throttle shaft, has been thinned extensively
i have to run stock choke diameters.
The exhaust manifold and system made the biggest single gain, from 98bhp on the dyno running the dyno exhaust- to the 120bhp i have installed in the car- although i modified the carburettor at thte same time as fabricating the exhaust


Posted: June 26th, 2006, 4:25 pm
by sumplug
yep, treat them accordingly :)
iam surprised your engine is making so much by your spec, but i know you dont BS.A good race spec on twin 40's makes somewhere around mid 130 bhp to 140 bhp and thats with a much higher spec. that head must be really flowing with an exhaust to scavenge the cylinders quickly. iam very impressed. wonder what it would make with a higher spec? downside as you say is zero torque low down. wonder if yu need to move your power curve down to help torque for your slower track corners. are you allowed to ramair the carb by enclosing it ?? :D

Hi Simon

Posted: July 5th, 2006, 12:31 pm
by unoracer
Hiya Simon, I was interested to read that you use a piper race cam. I have just literally bought a Piper 320 race cam, for use on my 1500cc Eurosaloons uno. My head is a full race spec using 40mm inlets, and 36mm ex, together with recently purchased twin 45' webers. I appreciate that I will lose some of the torque/power lower down the rev range, and have to learn to keep this 'screamer' revving in order to make use of power at 6000 rpm plus. I am having the engine built at the moment, and (hopefully) will be competing at Cadwell on 15th and 16th July, so will let you know how it performs, and also let you know what bhp it develops.#

Guy, Great forum. It occurred to me that when reading your posts on experiences and work done on vehicles, it clearly shows why you are the worlds no 1 italian engine tuner!!

Posted: July 5th, 2006, 8:48 pm
by James Bowen

What sort of Power and torque figures were you getting on the old spec engine?

I'm assuming it was equipped with the weber 40 dcoes, and the piper 285 cam. Were the valves sizes standard?

The spec your trying should be good for 160hp? What pistons are you using???

Sorry, lots of questions. I'm giving thought to modifying a later Fiat Tipo head (Bigger standard valves). An improved head flow, will have to be accompanied with a better flowing induction system to make use of the increased top end potential. Possibly some constant velocity type Bike carbs, on nice long and straight(ish) inlet manifold runners. The cam is a 285 deg item, so really high rpm and big power figures are not required, more a nice fat and flat torque curve that doesn't fall away too quickly at the higher rpms. Max power probably circa 7,500 rpm.

The more SOHC spec's I get to hear about, and the results from them, gives me a clearer idea of where to go.

Many thanks, James

Posted: July 5th, 2006, 9:28 pm
by unoracer
Hiya James, Yes , I was using twin 40 dcoe's and the piper 285. I was using standard valves, only minor porting on head, and near to standard compression ratio. The last rolling road session with this set-up was 158bhp at the flywheel believe it or not! The torque fig quoted was about 115 from memory. The bottom end was lightened and balanced, but otherwise standard. The latest set-up will see over 170 bhp at flywheel. (I had it rolling roaded at 163 bhp with a very poorly holbay regrind cam and a brain dead engineer had not built the engine correctly, causing piston valve cut-out damage, but thats another story lol) So, with the piper 320 cam, and it being assembled properly this time, I am more than confident that it will be in excess of 170bhp, torque , I'm guessing poss 140 or so. The pistons are oem 3rd oversize. Block has been decked to allow pistons to protrude .8mm above deck. I am not a mechanic, but the head supplier gave specific instructions on the set-up, prep of block etc. I will let you know how it progresses. Pistons are still in Macedonia so I am starting to worry about being ready for Cadwell on 15th July! One thing that I am unsure about is sump choices. I currently use a standard strada 'tin' sump, with a pbs baffle plate, and high pressure relief spring. Do you think the engine would benefit from swapping to an x1/9 sump, bearing in mind they are vented for cooling, and possibly having superior baffles? I am aware that i would at least need to use the correct x1/9 oil pick up pipe as the sump is deeper?? Regards, Chris

Posted: July 6th, 2006, 9:55 am
by James Bowen
Thanks Chris. That's 10 ftlbs more than mine on similar spec, but running twin 40 Dcnfs. The exhaust shouldn't be the restrictor, as its a PBS 4-1 24" primarys (28" would be better I understand) and 2" outlet running a Jetex (Simson) stainless straight through box. No baffles or bends in the box.

The x19 sump has 1 plate which is 2" from the bottom of the sump and lays horizontally, and has a space for the 2" x 3" oil pick up to protrude through. There are no other baffles. Though I have the Windage plate from PBS as well. And run an extra 1 litre of oil as per PBS instructions.

I've tracked mine round both Anglesey and Goodwood with no apparant Oil surge problems. (My Dad had his eyes glued to the Oil pressure guage in case, and reported that it never wavered even on School corner) The car has Yoko A032r's so there's reasonable lateral grip. Apart from being alloy and slightly finned at the bottom, there is no more cooling. Without oil cooler (and before new engine) oil was getting to 130 deg C after only 5 laps of Goodwood. Oil cooler made a big difference, it now hovers at 80deg C.

What head gasket are you using? Goetze or Spesso or something else? And its compressed thickness any idea?

thank you James

Posted: July 6th, 2006, 6:19 pm
by unoracer
Hi James, I will be running a spesso race gasket, which is 1.6mm before being compressed (unsure of compressed thickness) The first time the engine was (mis)built, A goetze gasket was used, I remember it apparantly being 1.45 mm compressed thickness. It was interesting to read your oil cooler mods. I have the oil cooler exit/entryattachment that bolts on behind the oil filter(in my garage) and wondered whether I can utilise an oil cooler from a mk1 uno turbo. Is that what you did? I would be keen to know how I can add this little addition to keep the oil temp at bay, although with lower states of tune, I have never noticed the need to do this. However with 170bhp plus, it may be now worth thinking about!
Regards, Chris

Posted: July 6th, 2006, 7:33 pm
by James Bowen

Thanks for the info. I've got the Goetze head gasket (bought from GC) Seems OK, and not giving any problems. Re torquing the head after build was worthwhile. Re torquing again after initial running in was of benifit as well.

My block was milled, raising pistons 0.5mm above the deck, so squish is .95 mm. Though after talking to GC on the phone about raising compression, I don't think he particularly thinks it is of much benefit. (Guy???...... I know there's more to come on your thread in the GC V/W re Heads )

The oil cooler is a standard aftermarket 16 row 235mm wide item, that sits above the gearbox in the X19 and has air ducted to it from the passenger side air intake. The pipes are stainless braided and made up by Think Automotive who also supplied a Thermostatic (75 deg C) oil take off plate. I use a filter from a Lancia Y10 turbo, as its shorter, and fits in between the engine, and chassis. For road use, the cooler hardly operates. Without the cooler I never got the oil hotter than 80 deg C,
even blasting up the motorway for long periods. Makes a difference on the track though. I'll try to dig out a picture for you and post it here.

Regards James

Posted: July 8th, 2006, 4:51 pm
by unoracer
That looks like a very neat well presented engine bay James! I may well start working on an oil cooler mod over the winter months. I will see what the operating temps are like for the rest of this season. I use twin ITG foam filters, which have a cold air ducting pointing over them, but am considering the benefits of making an airbox with cold air feed to enclose and feed the filters/carbs with cold air, as I have often seen this done on racers. Is this something you have thought about?? I see you have also wrapped up your manifold/downpipe to keep temps down, as I have. This seems to be an important issue with the Fiat sohc, due to the ex manifold being directly below the carbs, keeping the heat away from them is so important. I have made a heat shield to deflect exhaust manifold heat away from carbs, but as I say, an airbox may improve things still further. My pistons are still en route from Macedonia, so I will now miss Cadwell unfortunately, as I am not prepared to 'rush' getting it built up, as it normally ends up with mistakes being made!! Anglesey is my realistic aim on 19th & 20th August now!

Posted: July 8th, 2006, 8:00 pm
by James Bowen

Funnily enough, cold air is something that I have been thinking about for ages. I have just modified the rear of the roof, to bring the air down onto the rear of the boot, as before it, simply scoots off the roof, into a mass of turbulance. As part of that, I have incorporated an air scoop, that catches the air on the roof, then directs it down to the air filter which protrudes through the rear engine cover. Its a "snorkle" abit like the FAZA effort, and the ones that the racing cars used to have. It appears to work to a limited degree. Not sure its a bit subjective and impossible to measure easily.

I have spent alot of time working out how to build an air box and trap the air, but went off the idea as it was too hard to fabricate a decent box cheaply, and having a ram effect , and pressuring the air box isn't really worthwhile for the speed I'm mostly travelling at, the performance gain is neglegable . Vizard talks about an increased air density of around 1.5% at 100mph from pressurising, where as cold air increases the air density more like 6% at that speed. There again, add the 2 effects and your looking at 7.5 - 8% increase. Maybe not detectable in terms of how fast the car is, but worthwhile decreasing intake temperature, in terms of detonation, etc.

Pictures to follow!! The manifold wrap makes a BIG difference to under bonnet temp. I have thought about the heat shield, I must sort one out a you have done.

Good luck with the build. I was looking at the FAZA book, where he talks about Abarth getting 182bhp from the 1500 SOHC in race spec!

Regards James

oil pump&sumps!

Posted: July 9th, 2006, 5:28 pm
by unoracer
I'm having oil pump problems!! My engineer has noticed scoring marks on the inside of the pump , and has recommended a new one be sourced. After lots of time trying to track one down, a supplier said they had one, and promptly posted it to the engineer direct. It has transpired that the oil pump they have sent is NOT for the strada, but for some huge commercial Fiat engine I'm told!! I simply can't track a new one down, and was wondering how different an x1/9 pump is, as I understand they use a longer pick up, and deeper sump? Can anyone throw any light on this? I would particularly be interested in any 'upgrade' pumps available. Am I right in thinking the alloy sump on the x/19 is designed to sit at a different angle compared to the strada type tin sump? If I can utilise the x1/9 stuff, it may be easier to source second hand if not new.