Turbo Killer…The Sequel.
There are a several reasons I suppose why I’m doing this, because I can, its not conventional, how much power can these heads potentially deliver, it interests me.
Turbo Killer came about because I wanted a Saab 99 to be quicker than a standard 99 turbo, this was achieved after much trial and error, although to be fair, there wasn’t much error, more development and experiencing the limitations of various fuel/air deliveries and why they didn’t work. It turned out so well we entered into 16v turbo territory with regards bhp.
I asked my good friend Dave Baker of Puma Race Engines to help with its development, if you’ve read the ‘Turbo Killer’ thread despite him having no interest in Saab’s he really got into the whole thing around this project and to quote him….
‘’After 20 years of doing this for a living I didn't think there was much about engines that could still surprise me but every time this Saab goes to the rollers it beats the expectations, I'd had for it. I'm frankly astonished that it's holding on to its peak power for such an extraordinarily extended rev range. I've seen engines doing this when there's something wrong with the exhaust design and there's no torque being produced so they just keep revving to try and produce the power but that's not the case here. At 73 ft lbs per litre it's putting out gobs of torque for what's essentially a fairly mild cam. It has plenty of low-down grunt, strong mid-range torque and a top end that apparently just refuses to die. The only downside is that having taken it as far as the uprated valve springs will let us we still don't actually know where the power really starts dropping off which means it wants to rev even higher than 7600. My computer simulation program says it needs to go to at least 8000 rpm for best acceleration. That means it has a useable power curve running from 2500 rpm to 8000 plus rpm which is almost unheard of’’.
Some reading can be had over on PistonHeads with conversations between Dave and his old friend David Vizard,
https://www.pistonheads.com/gassing/topic.asp?t=1096171 Dave Baker has long since retired from doing any engine work, so I have had to look further afield, I got to hear about a guy in Northern Ireland, long story short, basically he has most of Dave’s old customers, a testimony in itself.
He agreed to flow a head for one of my Evo 6 Tommi Mak’s about 2 years ago, it took him a while, but he is really busy working on full competition engines and I did agree for him to work on it between other jobs etc, when I got the head back from him, his final words were, ‘throw some boost at it and it’ll fly’ he wasn’t wrong, almost maxed out the standard injectors, Evo 9 injectors and Evo 9 80 series turbo later and we are at 400/400 and this is on standard airbox and cam, plus a decent exhaust, open the bonnet and it all looks standard, it now needs an uprated Evo 9 clutch and that should do it.
Back to the 8v Saab H series head…. What do I want from this build? More power obviously, considering we are at 175bhp and 150ft/lbs of torque and a very flexible engine revving out to 8300rpm on a standard heavy bottom end. I am prepared to sacrifice some low-down tractability and with this next level of tune its inevitable.
The initial head valuation was not good, I would love to see 200bhp, but 190bhp is maybe more realistic, only development time on the flow bench will bear out if the required flow for this kind of power can be reached. There is a large drop from the seat to the floor of the port, this is not ideal starting point, each port is different and waterways are quite close, plus the exhaust port is abysmal. The last comment heard was to the tune of….’no wonder they threw a turbo on it!’ The large drop from seat to port floor can create a vortex, flowbench work is needed to get round this.
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