@ chrismc - You're being unfair by terming data analysis as 'hair splitting', and particularly targetting myself when this thread is stacked full of such analysis. What is being done here - you asked about cams and then sung the praises of the past K-Jet outputs, not me - is the assessment of various populations of uncompared data and related trend analysis. The whole point is to remove cheap talk and tease out trends which must relate to facts, even if the facts are not known to a precise point. On track technique, one more thing that I will say is that the Bruntingthorpe thrash saw everyone in their 2.0l cars shown up by a Mk1 1.8 KR. Four hundredths off Tubs on his slicks to 60, and fastest overall to the quarter mile by .15s to Ian V / EGN, .2 to Tubs and .4 to CFJ. That's weight of course, but also somewhere in there is technique. Was everyone on the same diameter tyres? I doubt it. It's very difficult to make absolute comparisons in dynamic environments.
The implied shopping list here is Schrick splits. If that isn't the going rate, well I picked the number up from earlier in the thread!
I have some dyno printouts from Stealth (my old supercharged VR6) if that helps validate (or otherwise) the quoted ouputs from their rollers.
Exactly, so raise the compression and fit cams. How hard can it be? As jamesa mentions it is not all about having masif midrange, when driving hard you generally change gear at a point where you never drop into the sacrificed area anyway. The lower final drive gives even more mechanical advantage to aid the situation. Those top speeds are some what irrelevant, just how many circuits have a 2 mile straight allowing to get to that sort of speed?
In the past, folk never veered from ~ standard bottom ends, just habit and cost, and this continues today. All work on the head, and the K-Jet outputs quoted throughout this thread are essentially std bottom ends. True to a point, but only if a 1000rpm / possibly 1500-2000 rpm range can be identified where there is no loss. This is unlikely, and depends on the type of corners also / gearing again.
All of the folk? I cannot believe a few did not attempt to raise compression. I am sure I have read in the past that some folk were using raised compression. If someone cannot tune for a 2000 rpm window with whatever fuelling control, be it efi injection, Kjet or carbs then they should take up knitting.
It's not all about midrange on a track but we are not talking About a race car here, OP states fast road as well where midrange is used most.
So spirited driving on the main road, ok, you are still never going to get to 130mph very often. So fit a lower final drive. It really should be the first thing you do to improve real world performance. But it seems the transmission section is awash with tumble weed.
All cars named in the internet joiner table were std compression. AFR answer already sitting on the thread - aka the limitations of K-Jet
It's all valid points, lairy cams for me = hydro followers so 285 or more. The peaky comments were in reference to the dyne plot of the max torque being high up the rev range when compared to EFI it peaks midrange. But as you say if it does not feel peaky then this might not be what the OP wants, I thought chris wanted peaky? Some for him to maybe question further. I don't agree you cannot have great fun with KJet and I imagine all will agree. It just seems for the price of the cams, the setup cost and possible replacement parts in the hope of chasing the CFJ figures you could go EFI.... Anyway been said before. I had a little reflection on a run just now and the conclusion I came to is 10bhp here or 20bhp there makes little difference in the real world or on track, as mentioned it's all about the many other factors such as gearboxes FD's and being able to put the power down in and out of the corners. I know my car really struggles with a standard box... Look at the Curby results to see it's not the big power 1.8T's that got the Best times but the light weights with good boxes... So it brings it back to fast road and what cams would be best? Standard ABF with SEM
Lol! I am quite happy sitting at 5.5krpm all the way to Germany! Local driving is a hoot. 4.25FTW! or 3.9 at least if you don't like topping out at 120mph hehe! In all honesty 4.25 is fine for almost every uk track bar Bedford and even there it isn't so bad. Gurds
All of them, no head skims or production variations, gasket thickness's? That is 1 example of a specific engines AFR. It hardly means that others could not obtain a satisfactory result by variation of components or engine hardware. The cam duration versus compression ratio will be an interesting thing to explore. 270s on std compression may be too long a duration to work effectively on a std compression engine. Losses in the midrange only marginally gained back at the top. And the more pronouncd overlap scavenging / pulse tuning issues. Possibly less is more and 260s may produce better results. I am awaiting with interest the inter cam vernier trials. It is about time Toyotec got oily hands.
My old ATB 4.25 with 0.91 5th got sold on to a lad from Glasgow who went to the ring with it in his Bergcup style car. Tiny petrol tank iirc, so regular gas stops. And ear defenders were worn all the way there. He certainly used up any mileage warranty I offered on the box.
see my plots for 264's as ref Anyway, if anyone wants to see the intercom timing results happen sooner please donate to smudge@gmail.com as I have no monies ATM.
Having driven the same car on track before and after 'optimised' Kjet to MegaSquirt, there's no comparison. Its nearly 10mph quicker up the hill on the Nurburgring. That's real world track performance. I'm planning to go 2L 16v in the track car towards the end of this year - I fancy another crack at Curby with the 8v first. One last crack at the 29 second barrier in an 8v. The spec will be a stock ABF bottom end, ported head, Schrick 260 cams (I've got either a shed head or the Blydenstein head from Dex's old 2.1, which is where the cams came from). It'll be running Megasquirt. Let's try and see how much difference the mappable management makes. The Megasquirt results on Gurds' Mk1 were a real eye opener for me. I think that's a game changer as to how 2L 16v tuning should be approached, especially in lighter, low-geared cars, where you can map a more aggressive ignition curve to take full advantage. As already said, the Megasquirt and stock cams would be my choice on your engine, and the first place I'd spend the money is on the gearbox, but it's your car and your money. Good luck with whatever you decide to do. Either way, you've still got the option to go standalone at a later date, and get some real performance out of the car
Send a sizeable offering and I gladly dirty my hands for a worthy cause . Then again I might do all that including taking time to process data and still some will not 'get it'.
