ando76

Yep. That's it. Fuel pullover through the squirters. It does chronic things to mixtures and afr as outlined in old mates you tube video. 

It turns the accelerator pump squirters into a fuel injector. They just go open circuit. It's one of the most bizarre things I've seen on the dyno. Had a 2 barrel and 4 barrel crossy both do it.  Last time I was at Boetchhers on their hub dyno, Brenton their main brain and engine dude couldn't believe it.  He actually made me run the car up a couple of times so he could video it.  It's not something that occurs on their big dollar, US sourced v8's.  It actually does occur on very high revving v8 engines. 

Nah it's a tune issue. The rigidness of those styles is one of the things that leads to chronic fuel pull over.  Type fuel pull over into you tube and you will see what I'm talking about.  

After much research I've found a way to totally eliminate it. There are plenty of products on the market aimed at curing it, but they are all based around mods to the carb. None of them truly eliminate it.  What I have done does. The cars idle and start better, are way easier to tune and make more power.  No more 'tune out as best as you can and send it out, the customer will never know'.  

The four barrel kit will be available early next year as I'm happy with the endurance testing now.  The main part of the  2 barrel kits have been machined and are on their way back from Malaysia.  Sadly we had to send them overseas as making them here was just not viable. 

They will be fine on a v8. It's solely an i6, 2 or 4 barrel issue. Doesn't happen on Weber equipped i6 engines. 

Be very careful with the aftermarket styles that use nolathane bushes, especially on a toughie. I've recently re-designed the engine mounts I was doing (Ryno mounts) due to stuff that I've found when dyno tuning cars with solid mounts or nolathane style mounts. 

I once thought solid mounts or those Neo style ones were they way to go, but I'm now 100% convinced that it's not. You need dampening of rubber. Mods like the ones Dean has done is very common in speedway and they make the standard mounts last.  That mod is way cheaper and effective than an aftermarket mount. 

Xd versions of these engines had no centre bolt from memory.  I will stand corrected tho. We run extended 9/16unf bolts on the race motors for vac pump drive mandrels and ps pulleys and they never come undone. Hence my harmonics comment. I wasn't being a smart arse. Well maybe a little 

If the threads in the crank are fine, and the bolt (9/16 unf on early and metric crap on late model cranks) check out then I'd be looking at harmonics or just loctite it and hope. 

Did someone say harmonics.......

They do awesome work at a fair price. I sent another customer engine down to them last week. It got there Monday and they are onto it.  

Except the chamber shape on the outside is like no other x flow head.  I don't believe gem would have anything to do with it as they wou,don't have HF cast into them.  My guess is it was a low production factory item to test something and they somehow made there way into a few production cars. 

That's the same as my mystery head from my post back in September 2013.  I still have that head here. It's very weird. I age never seen another one, now there are 2.  Hmmm

I'm with Greg. Zero deck with those pistons and a c2 head would yield very nice compression.  I've taken big hp and torque blocks to .060 and I know others have taken them further so be guided by that. 

Balance is pretty much a must if you want reliable trouble free running on these old girls. Factory tolerance on these things was very wide. 

Id be using that engine as a base for sure, especially if it's fresh. They generally have anything from .045-.050 deck height so giving them a mow, even with the dish pistons, nets good comp. add in a c2 with .040 off it and your in good comp territory if it's .040 over 

Bang for buck the BA/BF & FG motors make more hp. That's a given. We race against several up here. Most get 275rwhp with just cams and tune on $300 wrecker motors.  

You have to love crossflow engines to want to make power from them as they are very expensive to build to that same power level. They are after all a very old engine.  

Funny thing is in our form of Motorsport the crossy's still dominate the ba/bf. why? because of their torque and the weight penalty that comes with the Barra. 

At the end of the day the buyer will make the choice. I've got several customer crossflow engine builds on the go at the moment so the interest in them is still there. I make a point of informing all my customers at the very outset that it's not going to be a cheap exercise.

You may want to do your research on that car a little better. It never set fastest time at an Aussie title with the previous head, nor broke the Lismore track record with that other head.  It never top qualified on points in an Aussie title and certainly wasn't able to pull the wrong gear set before. As to the legality of the car, my opinion matters for squat. It passed scrutineering before and after that meeting (the top 5 cars all get inspected post race) and the Queensland title, so therefore it is legal.  

Your entitled to your opinion on whether it's an achievement or not, as am I. Sadly this thread is going down the same road as a couple of weeks back. Never mind we should have some further results shortly to bring it back on track. 

100%.  And we will just keep doing what we do.  When you do a head for a bloke and he puts it on and goes and sets a track lap record at an Aussie title, is the fastest car in qualifying,  highest point scorer after all the heats and qualifies on pole for an Aussie title against some of the biggest budgets and best cars in Australia - you must be doing something right.

Real results as you say. Oh and he was saying he had the wrong gear set in, but it still pulled through that. Imagine what it would do with the correct gear set.  Oh you don't have to. It went to the Qld title and won that feature by the length of the straight after starting in 13th. Another real result. 

I have no doubt that the Mr Darrin Morgan of Reheer and Morrison knows his stuff as I'm sure he is well paid to do that job and that job alone. Myself and Cam both do what we do as we are interested in the field and when time permits, we play. I'd love to be paid to do this stuff all day, as would cam, but the reality is the amount of people making a proper living from it is minimal.  

Theories abound and always will.

Agreed Matt. It is a black art and whilst the unknown author in Sly's post doesn't mention anything about intake to exhaust percentages, he does raise some very valid points.  In particular the flow bench being a constant pressure, something the engine in dynamic form never sees.

He sort of contradicts himself a little when he says "Professionals understand that designing an exhaust port on the flow bench has nothing to do with how much it flows, but everything to do with how it flows and at what air speed. The exact size, shape, and air speed of the port in conjunction with how smooth it flows, are the primary points to consider.  

 Isn't that what the bench is measuring, how it flows and at what air speed?  Perhaps he is saying peak flow is immaterial but how it flows is more important? Agreed that designing the exhaust port primarily on flow bench readings is probably not the best way to go.  But you want ex flow.  Look at efi Windsor heads.  They are just junk because you can't even fit your thumb in the exhaust port.  Improving the intake on those heads is an excercise in frustration, cause they still won't work - hence the reason aftermarket alloy Windsor heads sell so well. 

For me the flow bench is a tool used to measure gains (or not) from changes in the (complete) port shape, including chamber of course. Vizard and others theories are just that, theories. Everyone has their own idea on what makes engines fast.  Supercars is a classic example of this. All different ideas, but they all come together and are within tenths of each other. 

For me it's purely physics. The more you get in - the more you have to get out.  More air in, equals more fuel in, equals more waste to deal with. Yes the exhaust is a pressure system - not a suction system but it must be efficient or cylinder evacuation suffers. 

Anthony changes the heads on his flow bench so that they are blowing when the exhaust port is flowed.  Yes it's not the same as the dynamics happening inside the engine, but it's as good a tool as any to measure stuff that can then be tested in the real world to see if there are gains or not.

Cam runs the head section there and quality controls all my stuff that goes thru the shop. He is my friend and has been for many years. We both had GT as our mentor.  

ylu will not be disappointed in their work. 

I use and recommend Engine Engineering at Rocklea. I send my stuff 1800kilometres to them.  Why? Cause they are good. They treat x flows with respect, something other machine shops struggle to do. 

Agreed. The manifold is a terrible restriction in speedway classes forced to run the visually standard manifold. Marusic's head makes some solid numbers. 1.925 valve would be helping there, but none the less very good results.

Brenton also removes a lot of the intake guide to the point that there is none protruding into the intake runner. We have never done this due to concerns about valve stability under sustained high rpm.  I imagine it would be less of a concern in short duration motor sport. Perhaps it's time to try that in a runner and see if it makes a difference. The guide boss is actually a fairly big restriction to flow.  I know Ken Lowe makes his own nitrous nozzles for this very reason.  Hmm. More things to try. 

10 hours ago, LJDB said:

how much hp would your typical stock alloy head flow?

Go back to the very first pages of this thread where Sean flowed a stock head. From there you could use the multiply by 1.5 or use FORDMAN's figures to get a rough idea 

Most of the programs have a theoretical horsepower figure based on cfm of flow and a number of other factors.

Solid result there mate. Thanks for sharing. 

It's an expensive game playing with them for sure. 

There are several designs in the exhaust thread mate. Have a look. Some of them have even resulted in reduced et's 

Super street up here must run mufflers. Super street up,here goes down to 11.00. But it's an IHRA track and they change the rules every bloody meeting and even halfway through a meeting.  

I'm pretty sure Willowbank runs by the books. Non Andra/ IHRA tracks like heathcote and others let you do what you like really. 

My car will be ready after May 2018 mate. I'll drag the trailer to wherever.  Actually Willowbank in th cold of winter would be nice. Be a bit different from racing where the air is 3000 above sea level.