Nice work, Jason. I just picked up a 1600 X-Flow engine (AFT code I think). I haven't whipped the head off to check the valve sizes and condition. Do you know if the 1.6 valves (or at least the seats) are the same as the 2.0? Am I right in thinking that the X-Flow has 7mm valve stems, so switching to earlier 40mm valves would need a change to the earlier style guides, or rebore of the 7mm ones? What's your backlog like for head porting?
Can you not use the valves out of the AGG head. These were 7mm stems, and 40/33 combination. Please correct me if Im wrong. My AGG valves measured in at this.
Hi Mike, I can confirm this for you as I've sent a couple of these down to Jason for development purposes Valves, springs and seats are the same size as the 2.0L OBD2 ABA heads. 39mm inlets and 33mm exhausts both with 7mm stems and same length as hydro counterflow 8mm stem valves. The 1.6 and OBD2 2.0L heads also only have single valve springs....whereas the OBD1 ABA heads it appears all have double valve springs but the same valves and valve seats. PM me if you want any more info mate Tim
Hi Mike... Backlog....long...tho not so much a backlog but lots coming in...tho Im sure something can be sorted. Tim will fill you in on all the train spotter stuff!...but i can tell you the std exhaust seat wont comfortably take more than a 33mm valve. The intake seat will take a 40mm valve tho which is showing very positive results..albut race flow that needs a 41-42mm valve to achive the same results Im the old style head. It's no problem going back to an 8mm stem if o.e valves are used as the gain in valve head size far outweigh any potential loss from the thicker stem. I think AFT is a non swirl head. They take more work to get the best from them compaired to the swirl head, but you don't have to worry about breaking through like you do on the swirl head...very much swings & roundabouts..depends what the application is...the peak flow is similar but mid flow totally different without a few tricks thrown in.
Hi Jason. I'm not building a full race engine with this one. This is an upgrade for the 2.0 8v that's in the track car, and an interesting experiment in how much power can be got from a X-flow head on 40/33 valves, as opposed to the Pack D counterflow head that's in there now (40.5/35). I'm undecided at the minute whether to go for a solid lifter conversion, or just buy the lumpiest cam I can for hydraulics. Rev limit will be 7500 max.
Evnin Mike... I've tested a few of both types now and the crossflow as an average flows around 10cfm more inlet flow than what you currently have, and that's from a 0.5mm smaller inlet valve. The 33mm exhaust flow on the crossflow is very similar to the older heads when modded along the same lines, and can in fact rival an average flow 35mm exhaust when the 33 is done properly. The problem with the crossflow is the inlet flow is so good, that by ratio, the exhaust flow looks to be lacking. But...I've seen very similar dyno results from very high flowing exhaust ports and average flow exhaust ports. Cam choice is going to be down to the pistons used...so a safe max of around 11.25:1 will match with a cam of around 280-285 degrees, which will peak on a 2ltr around low to mid 6's...so no real need to run past low 7's.
I was going to build this on top of Claire Tippet's old race engine, provided the pistons aren't starting to break up when I take the head off. If that turns out to be the case, I've got another couple of options, including a set of 83mm pistons from a 1900 conversion. I'd need to get those machined down to suit a longer crank, if I went for them, or I could use the 1900 block, which I've already had decked to give about 11.3:1. I don't plan to go to forged pistons though. The engine's currently built on a GU block, so I think I'll have to get the drain hole on the front of the X-flow head partly welded up. I do know a man who's very handy with a welder though. The 'first alternative' block is an early PB, so has the same problem I think. Its got a piper 285 solid tappet cam in it at the moment, I was thinking going 'up one step' to a 290-300 duration. There's plenty of torque with the current setup, so I figured that maybe it could take a little bit more cam. I actually want to extend the power band to nearer 7500, with a particular objective in mind. On Garage Streamline's 'tough love' rollers it produced 150 bhp in its current form (149.7, if anyone's being pedantic). The management is megasquirt. I'm hoping the X-flow and maybe a slight cam upgrade would squeeze another 10-15 bhp out of it. Do you think that's realistic?
It certainly is. I wouldn't run much more c.r than that on a decked piston...that's one of the reasons for the failures. .but combined with around 12:1 c.r's. A solid 285 piper is 280 degrees I think is'nt it?
All good stuff. If I can add a bit, the bhp numbers are what everyone concentrates on, as boys do...... What I would add is the fun you can have by extracting every little bit out of the bhp you have..My 8V mk1 doesn't have a boastable bhp reading, but it has provided countless fun in my mk1 rally car. Its done, lots of tarmac rallying, a hand full of autocross, a couple of sprints, one trackday, 50 miles commuting (!!!) and won a reasonable amount of tinware. Priceless.......And every time I fire it up on those twin 45's , I smile. I do, like everyone else, want to spend a shed load more making it better, however get them used.
Yep - according to Piper's website. Just under 11mm of lift though, so maybe there's a better option. On the hydraulic front, there's a Cat Cams 282 with 11.5mm of lift... tempted to go for something a bit more lairy though.
'Plan A' is still a plenum and megasquirt - probably a custom manifold, based on the bottom half of the X-flow one. I've got a set of bike throttle bodies I could use (from a BMW 1200), but I'd rather stick with the plenum. Should be plenty of room for either setup, down the front of the Rocco. I was looking at those... looks like a decent option.
Bike bodies...Go for it! With open induction, a 300 degree cam, 11 & bit:1 c.r, a sub 100cfm head & the right exhaust on a 2 ltr block you would see around 175hp.
Have to say I'm more inclined to stick with the plenum setup for now. The bike bodies are almost the same spacing as a 16v head. The plan was always to use them on a 16v build, and I think that's the more likely long term home for them. I'd have to chop them about to fit an 8v.
You could go for something like this :- p.s..thankyour mr brown Mr H, hope your free in the upcoming months, Id love to get some work done..btw did you get my email ? Rich
Maybe because a completely standard ABF head & block can produce 175bhp & 162lbft (of course with management and exhaust as per what the 8v with bike bodies would also require) Seriously though, I am interested in seeing the crossflow engine with plenum as Mike is suggesting. Is this something we might see in the near future?
