Crossflow mild build, need advice

[XFChris 126]

Hi All,

 

I would like to convert my dual fuel XF to straight LPG. The motor in it now is getting long in the tooth, so I would like to build a fresh motor for it that's a little bit warm

 

My goal is to have something that gets good economy, can tow a tandem trailer with a car on it no worries, and to have a bit of fun off stoplights and stand up to more modern 6's. In essence, it will be a daily driver that I can have some fun in with good off the mark acceleration.

 

Here is my plan. 

 

4.1 block with fresh rings+ bearings + gaskets, replace other parts if needed. car has an 86DA now, spare motor is an 84DA, not sure if the 86DA will be be better, as i dont plan to rev past 5000. I probably could have a builder balance the block anyway

Comp ratio at least 9 something, not sure how high I can go and keep the motor safe, have heard 10 something is fine if LPG only

Reco head, new pushrods, port matched and valve work to suit the cam. Have a C2 and E1 head to choose from.

Mild cam, something  like the Camtech CT142 517(A) 218 @ 50  duration, Have heard some guys praise this cam for daily use

EFI manifold

IMPCO 225 mixer, B2 convertor OR BLOS mixer, OMVL convertor

TFI Dizzy with MSD 6AL2

Upgrade from XF T5 to EF/L T5 Taller 5th apparently, and stronger box overall

Upgrade from 2.77 diff to 3.23 or 3.45 leaf spring diff from E series

Extractors with 2.25" exhaust Already on the car

 

Do the 84 and 86 DA blocks have much difference, aside from the 86DA having a bit better balance and E series crank?

 

How about the C2 vs E1 head?

 

And am I going too mild, or wild a cam for straight GAS? I have heard the 4th cam down the list is a good choice for power http://www.camtechcams.com.au/ford_6cyl_xflow_hyd.html

 

Any other opinions/suggestions are welcome.

[ando76 4,354]

I think the later blocks are essentially the same as the earlier blocks - possibly a bit better casting - possibly not.  won't really matter unless you plan on going .060" oversize and big comp - which you are not.  The EF crank in the 86DA block does make them RPM happier and seat of the pants feel between to two is that the EF crank is smoother.  having said that - when I bolted on a better balanced inlet manifold to my 84da block motor is RPM'd like an EF crank motor, so maybe there is something in that.

 

EF crank seal and 86da block seal are different to 84da neo seals from memory. 

 

I have little experience with LPG but I have heard that it can take a little higher compression than fuel - but to be honest I am well and truly out of my depth as I have never played with cooking gas.  I'm sure someone else on here has. 

 

the rest of the combo sounds good.  Torque will be your friend in this application so comp and cam to suit and 250/250 rod combo is the go. 

[Clevo120Y 815]

You can go high 10's on comp with straight gas, I would use the C2 head as gas likes lots of chamber swirl to produce torque, if your going to use the EFI manifold then weld up the injector bosses so you can grind out that section to match the head, that section of manifold has a small cross sectional area so it needs to be opened right up and then matched to the runner tubes as well.

The 86 block has a 1 piece rear main the same as e series blocks, the 84 also has a 1 piece but it is a different size, I always like to run an EF crank in a 86 block as like Tony said I find them smoother.

Head work, well I'm always going to recommend some porting hahaha but with gas I would run a bigger exhaust valve, gas likes more exhaust flow. Intake if the budget allows to run a 1.84 valve then do it, a nice 3 angle seat and a backcut on the valve and your golden.

That cam will suit what your after in my opinion.

PS you don't get a block balanced you can get the rotating assembly balanced but in this application I wouldn't really worry about it.

[Stumps 311]

You may find that cam a little bit big for LPG, especially an Impco 225, you might want to step back to a cam around 208 degrees, the lack of vacuum when using that cam with LPG will make the car a bit doughy off the line, I've used it before on LPG setups and found it to be a little underwhelming below 2500 rpm barely better than a stock setup.

 

The 225 will run out of puff before the cam will anyway as they only tend to run out to 4200-4400rpm.

 

Crow has a good dual pattern cam part number 14776 which is 204@50thou IN and 214@50thou EX, LSA 112 degrees, rpm range 1500-4500, while I haven't used this cam personally...Yet, I 've had more than a few blokes who run LPG tell me it works really well with the 225/EFI manifold setup as the rpm range of the cam pretty much matches the maximum flow rate of the 225, and provide excellent low down and mid range torque as well as excellent economy.

 

The Camtech cam you listed is a good cam but it is definitely better suited to petrol setups, I used it on my XC with two different type of LPG setup and it was good out on the highway and had plenty of legs which matched the impco 425 that I was using, but it was hard to live with around town and it was embarrassing having some spikey haired little punk in a corolla smash my XC off a set of lights up to 60 km/h.

 

As for comp ratio aim for 10:1 or slightly higher, that will work well with LPG.

[Clevo120Y 815]

Agree with Stumps, I looked at the wrong cam. I was looking at the 3rd cam on that list as the one I would use. The crow suggested above I like the extra exhaust duration because of what I mentioned earlier, I don't like the 112 lsa tho. I would be grinding that on a 109/110 lsa

[XFChris 126]

I think the later blocks are essentially the same as the earlier blocks - possibly a bit better casting - possibly not.  won't really matter unless you plan on going .060" oversize and big comp - which you are not.  The EF crank in the 86DA block does make them RPM happier and seat of the pants feel between to two is that the EF crank is smoother.  having said that - when I bolted on a better balanced inlet manifold to my 84da block motor is RPM'd like an EF crank motor, so maybe there is something in that.

 

EF crank seal and 86da block seal are different to 84da neo seals from memory. 

 

I have little experience with LPG but I have heard that it can take a little higher compression than fuel - but to be honest I am well and truly out of my depth as I have never played with cooking gas.  I'm sure someone else on here has. 

 

the rest of the combo sounds good.  Torque will be your friend in this application so comp and cam to suit and 250/250 rod combo is the go. 

 

 

Cheers, I'll work with the 84 DA block then

 

You can go high 10's on comp with straight gas, I would use the C2 head as gas likes lots of chamber swirl to produce torque, if your going to use the EFI manifold then weld up the injector bosses so you can grind out that section to match the head, that section of manifold has a small cross sectional area so it needs to be opened right up and then matched to the runner tubes as well.

The 86 block has a 1 piece rear main the same as e series blocks, the 84 also has a 1 piece but it is a different size, I always like to run an EF crank in a 86 block as like Tony said I find them smoother.

Head work, well I'm always going to recommend some porting hahaha but with gas I would run a bigger exhaust valve, gas likes more exhaust flow. Intake if the budget allows to run a 1.84 valve then do it, a nice 3 angle seat and a backcut on the valve and your golden.

That cam will suit what your after in my opinion.

PS you don't get a block balanced you can get the rotating assembly balanced but in this application I wouldn't really worry about it.

 

Cheers for the tips, I'll definitely take those on board. I haven't set a budget yet, I don't want to spend huge $$$, but I do want to things right the first time.

 

Ah silly me, it's the crank + pulley etc that gets balanced, might not do it if you say its not needed, though I will probably get a new crank pulley anyway.

 

 

You may find that cam a little bit big for LPG, especially an Impco 225, you might want to step back to a cam around 208 degrees, the lack of vacuum when using that cam with LPG will make the car a bit doughy off the line, I've used it before on LPG setups and found it to be a little underwhelming below 2500 rpm barely better than a stock setup.

 

The 225 will run out of puff before the cam will anyway as they only tend to run out to 4200-4400rpm.

 

Crow has a good dual pattern cam part number 14776 which is 204@50thou IN and 214@50thou EX, LSA 112 degrees, rpm range 1500-4500, while I haven't used this cam personally...Yet, I 've had more than a few blokes who run LPG tell me it works really well with the 225/EFI manifold setup as the rpm range of the cam pretty much matches the maximum flow rate of the 225, and provide excellent low down and mid range torque as well as excellent economy.

 

The Camtech cam you listed is a good cam but it is definitely better suited to petrol setups, I used it on my XC with two different type of LPG setup and it was good out on the highway and had plenty of legs which matched the impco 425 that I was using, but it was hard to live with around town and it was embarrassing having some spikey haired little punk in a corolla smash my XC off a set of lights up to 60 km/h.

 

As for comp ratio aim for 10:1 or slightly higher, that will work well with LPG.

 

Crap, meant to put CT142 503B-110a @ 208. Rev range of 1400-5000, which is one step down from the previous cam I quoted. I have heard that Crossflows do not like dual pattern cams, but it may be different when on LPG, as LPG seems to like bigger exhaust. I know a guy who can do custom grind cams so I may speak to him and see what he would recommend. Around town is where I want this car to shine. Cheers for the info.

[slydog 7,873]

Well Ken Moss has the fastest NAT ASP xflow and uses a dual pattern cam...I guess you can say they work.For gas I'd use a dual pattern anyway.Even if it was only for a tad more exhaust duration then inlet but same lift values.

[Lord_fahrquhar 2,580]

Ef crank if you can get one, std bottom end

 

I'd go a c2 head with efi pistons. This will give a fair whack of compression but you machine down the toungue in the chamber to reduce hot spots for pinging.

 

Standard valvegear should be ok for that too.

 

With the camtech cam it will be a torquey little bitch and pull like a serial masturbator between 1500 and 3k. I find mine is a bit meh over 3k but it has more to do with the efi manifold. I'm working on a eb manifold conversion to resolve that shortly. That should help with a boost related issue down the track.

[wagoon 2,429]

Agree with Sly, Jason/TF 250 had a roller cammed crossy it is dual pattern cam and his cortina was good for 11.5.

 

I would agree with all the above, but how is your supply of LPG. Just make sure your supply of LPG is stable in quality. The better the fuel quality the higher compression you can run.

 

Not long ago I was planning a mild crossflow. Machining alone was going to be $2500 but that did include balancing. That was all new bearing, new cam and lifters, new balancer, crank grind/linish and head work. The bill will rise pretty quick if you need new pistons and a rebore, new valve spring, new valves/oversize valves which means seat size change. Funnily enough the machining work on my roller cammed crossy was only not that much more than the mild rebuild but I already had a few of the parts needed.

[PRO250 1,506]

While where talking about this. I have a 200 rod crossy In the shed small 208 cam 10points of comp or there abouts its done 8000 km was on LPG and was built for it. went good in a auto 2.7 geared falcon I could not use it for boost so its in the corner mint engine $2500 may be another option over building one 

I have little to offer on this LPG is for BBQs but seem to work with a windmill  most of its been covered anyways

No ones ban me for trying to sell one of the engines I no longer use

[gerg 10,871]

All great advice from the usual crossy freaks on here but I'll add a bit more on the LPG thing.

 

Stumper is 100% on manifold balance. My dad's XF was a warm 4.1 EFI and was a smooth revver all the way to 5500. That exact same donk in my LPG Corty with a Redline 2-barrel manifold was shitty above 4000 and felt like it was going to shake itself to bits. Bad cylinder balance from poor manifold design.

 

Now the LPG. You'll need some decent plenum volume and a manifold that will give even flow for each runner. Although EFI manifolds are more even than carby ones, they have small plenums and runners and still favour the two middle cylinders, as they are right in front of the throttle.

 

The factory rating for the EFI donk was 120 kW. Not bad for its day considering the 5.0 Dunnydoor made about that much. But the EFI manifold might only handle 150 kW before maxing out, and seeing as LPG takes up more volume in the intake than just plain air or air/petrol, that power potential becomes even less. The throttle drawing air from the hot side of the engine adds to the problem.

 

So your choice in manifolds may not be the best to reach your goal, which is to match the performance of a modern V6 (around 180 kW).

 

Ditto for the mixer. 225 is woefully small for any kind of performance engine. Go at least the next size up or a GRA single. Aussiespeed manifolds are not perfect but miles ahead of anything else, so I'd go with one of them in 4-barrel (for the plenum volume).

 

So go bigger with everything... Manifold, mixer, ports, valves, cam, exhaust... all will work together to give you what you're after. No point in having one weak link in the chain.

[ando76 4,354]

Good info gerg.  I have flow tested the aussiespeed four barrel an there is a slight difference (8cfm) on number 3 runner when compared to 1 and 2.  ten minutes with a die grinder in the right areas on 1&2 and even cfm is achieved.

 

Oh and I believe I was the one talking about even balanced manifold - not my fellow crossy freak from over in WA.  but hey all good.  The point is more important than the poster.  

 

sounds like LPG is a lot like methanol.  I know for a fact that the lpg engines I have pulled down are just a clean as a methanol engine. 

[gerg 10,871]

Sorry Ando props to you, i didn't read through it all properly. If anyone knows about that subject it would be you with your speedway experience... and yes you are a crossy freak (I'd be proud of that).

[adrianphu123 73]

How do you balance the EFI manifold? one idea i had was to enlarge the ports on the plenum on 1&6 cylinders a tad more than 2&5 with 3&4 being the smallest

[ando76 4,354]

Its 3 and 4 that get all the flow because of the proximity to the centre plenum (one that rides on top of the tapet cover) and also the throttle body. 

 

just by enlarging the ports you are not guaranteed of improving flow in and aspirated form.  anything you do to the head and runners to address the imbalance is really a band aid fix.  better to start with a better flowing manifold or make your own plenum. 

 

Thanks gerg - I know I am a crossflow freak and I'm damn proud.  Maybe I should get some stickers made up like those Vietnam vets ones (not demeaning the vets by any means - just using it as an example).

[wagoon 2,429]

My initial thought for this build was to use Impco 425 with B2 converter as you can fit a holley base plate to the Impco and use it on any 4 barrel manifold, but wasn't sure if a 4 barrel manifold would suit for the reason mentioned above. The 425 is really easy to use.

This next part is from research I did into running LPG on a cleveland so from all that I have learnt about crossflows it should still be relevant. Basically when picking a cam, pick a cam that has an operating range 500rpm higher than you want. The LPG lowers the working range due to the way it works differently to petrol. The ignition is crucial on LPG but you have that covered but don't forget to upgrade the coil as well.

[PRO250 1,506]

Theres a member on xfalcon that run a 425 and 4barrel on a 250 in a XF it made 172hp thru a manual with about the same cam specs this bloke is talking about stock engine with comp and a stick

he also used it for towing a mid sized tandem if I remember right

[gerg 10,871]

Yep wagoon I found that exact effect myself with the shifting of the torque curve lower when on gas, with all else being equal of course. This is due to the already mentioned extra volume that the gas takes up in the intake, which tames the characteristics of the ports/camshaft. If you flip that concept around, you need bigger breathing to take the equivalent amount of fuel in.

[Lord_fahrquhar 2,580]

Custom plenum for the win... But...

 

Extending the plenum over the rocker cover is a pita for cleranace if you run big rockers and the alloy rocker cover.

 

The Ef manifold can be welded to the injection part of the xf efi and provides a good point to mount a gra mixer.

[Lord_fahrquhar 2,580]

Have you thought about vapor injection?

[Clevo120Y 815]

If you put a diffuser plate in the plenum you can distribute the flow more evenly, I'm working on this problem with the ecotech manifold.

[XFChris 126]

Ef crank if you can get one, std bottom end

 

I'd go a c2 head with efi pistons. This will give a fair whack of compression but you machine down the toungue in the chamber to reduce hot spots for pinging.

 

Standard valvegear should be ok for that too.

 

With the camtech cam it will be a torquey little bitch and pull like a serial masturbator between 1500 and 3k. I find mine is a bit meh over 3k but it has more to do with the efi manifold. I'm working on a eb manifold conversion to resolve that shortly. That should help with a boost related issue down the track.

 

Torque is what I am aiming for. EF crank will only go into a 86 DA block right?

 

 

Agree with Sly, Jason/TF 250 had a roller cammed crossy it is dual pattern cam and his cortina was good for 11.5.

 

I would agree with all the above, but how is your supply of LPG. Just make sure your supply of LPG is stable in quality. The better the fuel quality the higher compression you can run.

 

Not long ago I was planning a mild crossflow. Machining alone was going to be $2500 but that did include balancing. That was all new bearing, new cam and lifters, new balancer, crank grind/linish and head work. The bill will rise pretty quick if you need new pistons and a rebore, new valve spring, new valves/oversize valves which means seat size change. Funnily enough the machining work on my roller cammed crossy was only not that much more than the mild rebuild but I already had a few of the parts needed.

 

I will probably run servo LPG, Supagas pure propane is a little hard to get as they are only open during business hours where I am. The last rebuild I had done cost a bit under $3000 just for the bottom end, I don't want to spend that much this time around.

 

While where talking about this. I have a 200 rod crossy In the shed small 208 cam 10points of comp or there abouts its done 8000 km was on LPG and was built for it. went good in a auto 2.7 geared falcon I could not use it for boost so its in the corner mint engine $2500 may be another option over building one 

 

I have little to offer on this LPG is for BBQs but seem to work with a windmill  most of its been covered anyways

 

No ones ban me for trying to sell one of the engines I no longer use

 

Is that a 3.3 motor, or a 4.1 using 3.3 rods? And what effect does the 3.3 rods have?

 

All great advice from the usual crossy freaks on here but I'll add a bit more on the LPG thing.

 

Stumper is 100% on manifold balance. My dad's XF was a warm 4.1 EFI and was a smooth revver all the way to 5500. That exact same donk in my LPG Corty with a Redline 2-barrel manifold was shitty above 4000 and felt like it was going to shake itself to bits. Bad cylinder balance from poor manifold design.

 

Now the LPG. You'll need some decent plenum volume and a manifold that will give even flow for each runner. Although EFI manifolds are more even than carby ones, they have small plenums and runners and still favour the two middle cylinders, as they are right in front of the throttle.

 

The factory rating for the EFI donk was 120 kW. Not bad for its day considering the 5.0 Dunnydoor made about that much. But the EFI manifold might only handle 150 kW before maxing out, and seeing as LPG takes up more volume in the intake than just plain air or air/petrol, that power potential becomes even less. The throttle drawing air from the hot side of the engine adds to the problem.

 

So your choice in manifolds may not be the best to reach your goal, which is to match the performance of a modern V6 (around 180 kW).

 

Ditto for the mixer. 225 is woefully small for any kind of performance engine. Go at least the next size up or a GRA single. Aussiespeed manifolds are not perfect but miles ahead of anything else, so I'd go with one of them in 4-barrel (for the plenum volume).

 

So go bigger with everything... Manifold, mixer, ports, valves, cam, exhaust... all will work together to give you what you're after. No point in having one weak link in the chain.

 

 I probably should have been more clear about a modern 6. Taking on a VF/FG is probably too big a ask for a 250 built for torque. I'd like to give VR/VS V6's a good run though off the lights.

 

My initial thought for this build was to use Impco 425 with B2 converter as you can fit a holley base plate to the Impco and use it on any 4 barrel manifold, but wasn't sure if a 4 barrel manifold would suit for the reason mentioned above. The 425 is really easy to use.

This next part is from research I did into running LPG on a cleveland so from all that I have learnt about crossflows it should still be relevant. Basically when picking a cam, pick a cam that has an operating range 500rpm higher than you want. The LPG lowers the working range due to the way it works differently to petrol. The ignition is crucial on LPG but you have that covered but don't forget to upgrade the coil as well.

 

I have the OEM spec Bosch HEC716 or something along those lines, I might upgrade to a MSD coil. I heard of someone with a straight LPG XF that made good power with a 425 impco, but I have no idea how it went around town.

 

Have you thought about vapor injection?

 

Only briefly, it would require an ECU wouldn't it. I'd like to keep things simple. Though injected LPG sounds like it would be more efficient

[Lord_fahrquhar 2,580]

You can drop straight into an 86 da block or machine the crank down or the block out if it's an 84da.

 

The longer 3.3 rods allow extra dwell at the top of stroke, ie for a given amount of piston movement you get more degrees of rotation on the crank. Hard to do seeing mahle has stopped making pistons to suit. Commodore 3.8 eco tec ones seem to be the go but then the machining costs will blow out. But I haven't done anything like that with mine.

 

A good coil is a good idea but a better one is to add a street fire cdi added onto it. It looks like doc Emmett brown with a flux capacitor belted up his ass with a hover board.

 

The injected gas can be done as the computer splices into the ford computer and reads from that and learns it's shit. Of course some of us like cooking with bbq gas, others like to run their cars on it, some like dcoe's, some like injection.

 

I like playing with injection, but the xf system is a pos. much bette when an el system runs the show.

 

And if the spelling is shit I this I apologise the auto correct is being a dumb fucking whore and I just want to shove my iPhone 6 plus up steves jobs ass. You like how that feels Steve?

 

Next they'll do a fucking 8 inch version with an app that squirts lube. Fuck!

[PRO250 1,506]

200 rodded 250 mate better rod angle a lot say better torque so on

[matt_lamb_160 252]

Haven't really read any posts except the top one.

 

First do not use an OMVL POS converter. If you are using the std. EFI manifold a 225 is plenty (will handle 4,000rpm).

 

That 218 Camtech is bigger than needed if it will never see 5,000rpm. I think the 208 option or a 725 Tighe is better suited to the EFI manifold (good manifold if you want to tow).

 

If you want the car to backfire, make the plenum bigger.

 

If you want to pointlessly kill bottom end for no improvement in top end use a dual pattern cam.

 

Set your dizzy up for 14-16 deg at idle and 28-30deg total. Will easily handle 11:1. I have ran much more.

 

No need for gears any shorter than 3.23. Does not suit the manifold or cam I suggested.

 

If you want to use the 218 cam run a 4brl manifold (any) with a 50&70 (not a 1&20) 300a Impco with an adapter (the taller version) for a 600 baseplate or a 425 Impco. Make sure to run 3.23 gears or shorter. I'd run at least 11.5:1 compression on this setup.