who built this engine!

What a bananas photo. A GtB and an F50 fighting wheel to wheel. Guts. Respect.

 

I see what you're saying, and yes the CFD models do show what you're talking about. the graph legend is by axis vector, if the flow was to swirl then the 'Y' axis for example would show a slower velocity then 'X' or 'Z', that's one problem with 2D surface cuts, 3D animation and global plots help visualize the flow. the legend can also represent absolute or relative I don't recall off hand on the screen shots which it is.

there is also the highly dynamic nature of the cylinder volume and piston movement, and lets not forget the valves. I have some results on overlap, very interesting results there too.

Given the rpm range on any given engine and the resultant wave lengths based on where one wants the most Tq. This will also change how the port is tuned. I have noticed an interesting thing in reference to a given bore dia and volume and the ratio to port dia for maximum flow, still playing with it but it kind of just popped out.
PM sent btw..

 

For the F50 owner!. No disrespect intended as obviously a bloody quick GTB and a good driver, but heck that wing mirror that is in danger on the F50 probably costs more than a GTB!
Pete

 

Don't worry about the F50 door mirror, that went in the trash along with the rest of the front of the car a little later!!

 

Ooh yeah !! David is so right - the F50 spun to the outfield on a right hand corner but spun right around and onto the track backwards right in front of me just as I hit full throttle on the corner exit . I t-boned him HARD in the side dead centre and then the Testarossa behind me took his front bumper and bonnet off !!! The race was restarted with me in the pitlane after a red flag with my brother completing a lights to flag win and me coming from the back to finish in the points . Incidentally David built the GTB as well as my GT4 . Despite the carnage the F50 was put at the next round all Spickand span we say in blighty . Such good memories !!

 

Excellent news, and hats off to the F50 owner!!. Using his F50 well and having lots of fun I imagine
Pete

 

I thought I saw the GT4 with a Turbo at Combe many years ago?
Are you getting the old girl back on the the track?

 

Please forgive my lack of knowledge on the topic and I know your engine is built for race specific intentions. Can anybody with a 2v carbed car change out he DCNF's for a set of IDF's and get an uplift in power? Obviously you would need the new manifold and some tuning. What kind of increase would one see? How would the power affect the motor (torque vs. hp)? Fuel consumption, etc.

I am asking this from a more usable street car perception with no real race aspirations.

I am still very much learning and studying the car, engines and such and trying to get to a next level of knowledge.

Thank you!! oh, and great to see a GT4 handing the newer cars their lunch.

 

In short, yes and no. While anyone can certainly have an IDF manifold built and bolted up, in a stock engine there won't be a whole lot in terms of a power increase. With naturally aspirated power, everything in an engine must match the performance capacity of another component meaning a big IDF setup would not fully be taken advantage of minus many factors inside the engine built to take advantage of the new found flow potential with IDFs.

IDFs with their intake trumpets are also about 1.5" taller than DCNFs meaning they may be a squeeze under a stock rear hood, I'm currently looking more into options with regards to that issue.

Now, with a race motor or a motor like mine, solid noticeable increases could be obtained. I'd conjecture upwards of 25bhp+ would most certainly be possible. It's all about air through that intake valve, and 48IDF carbs with 38mm chokes flow some 20%+ more than a 40dcnf with a 32mm choke meaning power all over the rev range is most definitely there as volumetric efficiency is increased as a whole.

Going further on this would be to use 48IDF throttle body fuel injection which increases airflow even more as there is no need for a choke in throttle bodies. GOBS of air Performing such a modification is a nice little project as it dumps carburetors altogether and the EFI system can just be tuned on a laptop far more precisely not to mention more quickly.

 

Thanks! So what I'm hearing would be to match a higher compression, better spark larger valves on blueprinted heads and the value of the IDF would come into play... Am I on the right track.

 

What you saw was my mechanics trying to wind up the scrutineers . If I remember correctly we were working on changing the springs and drop gears and hung a turbo out the back ( from my RS 500 cosworth ) a but they kept talking about the 'blown' turbo and someone fell for it and actually complained to the powers that be . Oh how we laughed !! It's amazing how gullible people can be when they don't understand why you are so quick !!

 

Yes , totally on the right track . To get the best from any upgrade it needs to be done as a package so that it all works together . A decent porting job , some nice cams and a bump in compression will yells great results and we have seen 365BHP @ the flywheel. The bigger carbs and manifolds are really the icing on the cake to allow you to exploit the potential of the rest of the engine .

 

I use to run carbs like that on my VW!

 

Yes, IDFs are very popular on VW apps! Great carbs

 

I do remember seeing the turbo out of the car, I said to my wife at the time i wander where it goes as there was no exhaust mods to take a turbo!
It would be good to see it back on the track though.

Regards
Roy

 

Almost nearly correct... blueprinted head? What is that really? Blueprinting is a term that used to mean choosing the end of manufacturers tolerances that best suited performance, so the biggest end of the valve head diameter, longest rods in tolerance, most stroke allowed by the crankshaft tolerance. For years now engines have been made to sufficiently high tolerances that the term "blueprinting" is rendered pointless. It was valid in the days of choosing the longest rod out of a batch from BMC to build the ultimate production A-series Mini engine, but now we have our parts made to spec in the aftermarket, or use high tolerance production parts. There may just be a case for choosing the lightest rods (letter coded in the casting) for your 308 engine build, but that's it.

Larger valves, yes, but the most important thing is inlet airflow, blueprinting is not going to help you with that...

 

Some tuning... if that means inlet airflow and cams, then yes you will see a major uplift in power. The big increase being accessible by using the 48IDFs, but if you just use the heads unmodified and standard cams with 48IDFs you will be lucky to see 250bhp all else being standard.
Also if you just swap to the 48s you will loose bottom end and midrange progression as the intake velocity will be reduced until the rpm is towards the top end of its range.

Just one element on its own will never do the job. Put all the right elements together and you will get great results.

 

I am just learning about everything - thank you for the clarification! Hence I still have somebody else doing most of the work on the car. I am just at a point trying to understand everything on the car in hopes of one day wanting to work on it myself.

I do have a custom grind on my cams that everybody comments on who works on the car. I am thinking about doing more in the future but not stray too far away for changes that cannot be reversed on the block or sacrifice the ability to use on the road. I'm interested in gains - not building a race car like this GT4. it seems like an interesting modification. Larger valves have been something I am thinking about.

The build on this thread is a monster. It will be amazing after the the 360 crank and I would love to hear it!

 

Problem with all this is that it is based on sums, and the sums are wrong. Air doesn't flow in those beautifully illustrated straightish lines, so all that is derived or conjectured about its behaviour based on that info is wrong.

Bit like shaker rigs... I went to a seminar at Williams F1 a while back on vehicle dynamics, great emphasis was placed on the use of shaker rigs and modeling of suspension dynamics. When I asked the speaker how this helped get the car round any corners he sheepishly replied that it didn't! but it did help them go down the straights really nicely!

The real world is very hard to replicate on a computer and much time has been spent (wasted) chasing virtual tails. You can optimise yourself to death on a PC but you won't beat empirical testing.

 

Been away for a while but here's an update on the engine work with nice new parts that have been fabricated . It's such a shame most of these wont be visible once its all together .this is a shot of the billet main bearing caps .
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I really REALLY like this flywheel and the five and quarter inch triple plate clutch is just sooo pretty . Thought I would show them before they get locked up in the bell housing
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lovely work there. what's the weight of that flywheel? and what sort of clutch pack is being bolted on??

 

Don't have the weight of the flywheel to hand -perhaps David will chime in with the info as well as the weight of a standard one for comparison . I run a triple plate 5.75" diameter AP Racing clutch with unsprung sintered metallic drive plates . I will post a photo later but here's the water pump drive pulleys that have just been made
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A little update as more parts come in for this engine build- this the billet timing belt tensioner we had made -
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And then these little beauties turned up as well ......thank god it's only a 2 valve engine is all I can say !!
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