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mcfly94

250-300hp Crossflow

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Hey guys i been looking into building my crossflow a bit as im sick of the measly 100kw, drove my mates vy ecotec last night and this thing has so much more power, power that i want.

Im looking to build the motor within the 250hp to 300hp bracket. Ive gone through glens old threads on the forum and ive figured the gist of most i think, but i still have a few q's!

So far my plan is:

  • Fit Crow 14650 cam with valve springs collets retainers valve locks and anti pump up lifters to suit.
  • 2bbl aussispeed manifold with 6mm heat soak spacer
  • 500cfm 2barrel holley with 1/2 phenolic spacer
  • Fit ARP Rod bolts
  • Regraph dizzy to suit cam
  • Crow double row timing chain
  • New std. oil pump

Now the Q's, i want to aim to put up my CR to around 10.6:1, i think its at about 8.6:1

At the moment im running an early open chamber alloy head (pretty sure xd because of the shallow chambers) i think this has a cc chamber of around 53, it is a fully reconditioned head, that has been stripped blasted, and larger valves were fitted (inlet and outlet). And im running i think 22cc dished pistons (99% sure).

Can i get to 10.6:1 cr without roller rockers? im happy to build to only take 5000rpm.

With the rebuild kit would i be able to use the ACL 8cc dished pistons, which should bring it up to around 10.1:1, yet i want it around 10.6:1 and flats would go to far at around 11.1:1, could i shave the head? and if i could how much would i shave to get that extra 0.5:1 compression?

 

Things i dont want to do are roller rockers, guide andbowl work on the head, unless there a really a huge benefit cause i have a mate that could work my head pretty cheap, but are the price of roller rockers worth it? And 200 pistons and rods. I want to keep the standard rods.

 

I also dont want to go an amplified ignition system, however what dizzy would be best to use? i have the vacuum advanced type.

 

Also with ARP rod bolts on stock 250 rods, what type are required and what works required to fit them?

 

i hope you guys can set me in the right direction!

 

 

 

 

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The first thing I would change on your list is to run the 4 barrel manifold and carb, you will be running the limits of the stock rockers with that cam and I personally would use rollers for added insurance and less head wear. 8cc pistons and a C1 head would get you in the ball park cr wise. You will need some work on the ports to chase 300hp in my opinion.

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I have no idea how you want 250 flywheel HP and dont even want to fit the real basic gear. rollers will make your valve train last a heap longer as the crow 650 is getting some decent lift for stock rockers. basic head work is easy HP, might as well do it crap go buy a die grinder and do it yourself (just port the inlet side nice rounded work and just a zip in the exhaust port and then send it off for reco

 

with a 22cc pistons 0.030 deck hight 0.030 head gasket on a 3.68 bore and a 3.91 stroke that engine will have 8.97 to 1 comp and with 8cc pistons it will have 10.53 to 1 (i did this on a comp thing on the net so ball park)

 

why build to 5000rpm is the cam goes past 5000? and what does roller rockers go to do with its compression? and good ignition is also free HP but if you plan to use stock stuff just fit a MSD blaster coil and i spoze that will do 

250hp is 1 hp per cubic inch and althow people will say a stock engine can make that ( and im one of them) its not always easy to make it last

 

and fit a 4 barrel to it 2 barrels are for 4cylinders LOL


 

 

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TFI dizzy and a street fire ignition will gain more HP,fuel efficiency,easier starting and for less than $200.If you only rev it to 5000 a smaller cam will do and stock rod bolts are fine.No need for the Windsor ARP units for that RPM.Hell I spun a stock bottom end to 7200rpm,stock 28CC slugs,stock rods,stock bolts and only a good balancer.

 

That cam NEEDS diff gearing to work aswell so if you use 2.92-3.23 gears it will be a dog.

 

From Jase Stoodley...

One of the combos I ran through the years was very healthy and only mild and was fun on  the street i thought i would put it up here.

Block: 80da bored & honed .030
Crank: 250 ground & balanced
Rods: 250 machined balanced and 302w ARP bolts fitted
Pistons: ACL 21cc dish - combined with a 50 odd cc head was about 9.5:1 comp.
Cam: 230@50 530lift hydro - great cam for these motors!
Head: open chamber carby unmarked ported, 1.85" in, 1.55" exh valves, turned out it flowed 320hp
Springs: crow 7333 doubles - head needs machining for these.

Other parts included rollmaster chain, yella terra street terra bolt ons, crow pushrods, romac balancer.

Used to run a ultraflow manifold with a 500 holley went well but changed over to a cain and 600 vacuum secondaries and what a difference.

Was running a Hall dizzy with a MSD 6AL and MSD digital timing computer- the equivalent now would be a 6AL-2 programmable running 36deg total timing.

Used a 2200stall in a c4 with 3.7 rear gears.

the car was a full street car cortina ran 13.6 @ 100mph then 13.3@103 when i changed to the 600vac and made 200rwhp

The thing is every thing below the head is still the same motor in the car now.

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so im pretty new to building any type of motor, and what im pretty much asking is whats the best setup for the this area? i want it to last, and will spend whats needed to get it there, just plain on slowly building the motor up in the shed.

so what would each of you reccommend?

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crow 214 214 stock head no rollers stock dissy coil extractors will work with your 500 but will feel stronger with a 4 barrel this will work with a stock stall auto and stock gears and will pull good and all sorted out nice will keep/beat you mates crapodore easy fit 3.45s and he will have no chance and will not fall to bits cause its a small engine

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what sort of power would that make, i really want at least 250hp.

crow 214 214 stock head no rollers stock dissy coil extractors will work with your 500 but will feel stronger with a 4 barrel this will work with a stock stall auto and stock gears and will pull good and all sorted out nice will keep/beat you mates crapodore easy fit 3.45s and he will have no chance and will not fall to bits cause its a small engine

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Dave may disagree but I don't think that combination will get you there, great bottom end performer and a really good budget build and will still eat dunnydores light to light.

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and it would have to go with 3.27 gears and auto with high stall if need be, it would be good to get it to rev to 5500. I found street terra bolt ons for around $550 which It definitely get if If they benefit.

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Using your head rebuild the bottom end with the 8cc pistons, nothing special needed for the rotating assembly just a decent balancer, I would have the intake ports just cleaned up with some blending in the bowls, use a 4 barrel manifold either the aussiespeed or a redline cleaned up because there casting is pretty average, 465 vac sec Holley, pacemaker headers, Cleveland scorpion roller rockers (you will have some spare) they are fine and cheaper then the YT set. Cam tech ct142 528 camshaft and there recommended valve springs, regraph the XE dizzy or better still go for the TFI dizzy and MSD 6al-2 programmable ignition.

Your diff gears will be fine and a 2200/2500 stall would be good.

That should reliably get you over 250hp.

Others may tweak this combo, hope that helps.

Cheers

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people forget how much 250hp is hey, its heaps more then a injected 5litre commondore

that 214 214 camed combo i showed ive made 170rwhp out of and was a stock and i mean stock head not even valve springs but thats what killed it my mate was tyre frying it in 3rd gear and it was valve bouncing before i said dont do that it will,,,,,,,,,,,, it droped a valve

on the upside it cost $500 to build it and i just built a better one

 

 

Well I would say you give Dave $$$ for one of his engines and go smoke some some commondores :)

Id to that to. numbers mean shit i bet i have at least 2 160rwhp crossys that would rape the arse off a 200hp engine it not how much power it has its how it makes it :)

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A stock crossie with a 500 holley 2 barrel manifold, extractors/ 2.5 inch exhaust and a t5/3.23 diff

will give those heavy shit heap VT-VY commos a good run at the lights.

 

so many people see 250 motors as crap but they can produce heaps of mid range torque cheaply 

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its close at the moment, but im finding its running rich, but if i lean it out, it runs like shit, so i think im loosing power there.

A stock crossie with a 500 holley 2 barrel manifold, extractors/ 2.5 inch exhaust and a t5/3.23 diff

will give those heavy shit heap VT-VY commos a good run at the lights.

 

so many people see 250 motors as crap but they can produce heaps of mid range torque cheaply 

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Meh when ive got my bottom end together im starting a new forged bottom end so wen thats finish my short block will go up for sale... Proven 270rwhp with the right head and bolt ons lol but as yet has not proven reliable bloody things ;-)

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I would suspect if you wanna make 250 wheel hp your gonna need to rev it over 5k? Besides, you don't wanna be stuck in 4k town like i was for 5 bloody years.

 

Id also recommend the ignition Sly talked about up there ^

 

Defs roller rockers, Silly not too.

 

Put on a billet dizzy gear.

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Forget about HP for a daily.

 

I'd go for bulk torque, with say 150hp.

It'll jump off the line, and feel pretty damn fast, without seeming like it's going to drop it's guts.

 

Unless you balance the rotating assembly/EF crank etc,

a 4.1ltr crossflow will not reliably tolerate anything more than about 4250rpm.

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I would suspect if you wanna make 250 wheel hp your gonna need to rev it over 5k? Besides, you don't wanna be stuck in 4k town like i was for 5 bloody years.

 

Id also recommend the ignition Sly talked about up there ^

 

Defs roller rockers, Silly not too.

 

Put on a billet dizzy gear.

 

Yeah i heard about the dizzy gear, and i saw how much cheaper scorpion rockers are!

 

Using your head rebuild the bottom end with the 8cc pistons, nothing special needed for the rotating assembly just a decent balancer, I would have the intake ports just cleaned up with some blending in the bowls, use a 4 barrel manifold either the aussiespeed or a redline cleaned up because there casting is pretty average, 465 vac sec Holley, pacemaker headers, Cleveland scorpion roller rockers (you will have some spare) they are fine and cheaper then the YT set. Cam tech ct142 528 camshaft and there recommended valve springs, regraph the XE dizzy or better still go for the TFI dizzy and MSD 6al-2 programmable ignition.

Your diff gears will be fine and a 2200/2500 stall would be good.

That should reliably get you over 250hp.

Others may tweak this combo, hope that helps.

Cheers

what ratio scorpion rockers? and are they direct bolt on?

 

Forget about HP for a daily.

 

I'd go for bulk torque, with say 150hp.

It'll jump off the line, and feel pretty damn fast, without seeming like it's going to drop it's guts.

 

Unless you balance the rotating assembly/EF crank etc,

a 4.1ltr crossflow will not reliably tolerate anything more than about 4250rpm.

really? why cant they take more? pretty disappointing if thats all they make reliably!

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really? why cant they take more? pretty disappointing if thats all they make reliably!

 

Because they're a big dirty tractor engine in standard form, designed to live at 2,000rpm for most of the day.

 

In everyday driving, you can't take advantage of high end power anyway.

Make maximum use of what the long stroke six cyl does naturally - generate heaps of low down torque.

I would just try to build on that, unless you want to spend a fair wack of money.

 

You'll feel an extra 50nm of torque, so much more than another 50hp.

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how do i gain torque then, i definitely feel it needs a change of cam, because it pulls shit all, until i hit about 2000+rpm

Because they're a big dirty tractor engine in standard form, designed to live at 2,000rpm for most of the day.

 

In everyday driving, you can't take advantage of high end power anyway.

Make maximum use of what the long stroke six cyl does naturally - generate heaps of low down torque.

I would just try to build on that, unless you want to spend a fair wack of money.

 

You'll feel an extra 50nm of torque, so much more than another 50hp.

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You are reading this all wrong bro.You can have a 900hp car run 12's or a 400hp car run 11's.Which do you want? A dyno figure is just that and means next to nothing,a ET slip speaks real HP.Which brings us to the true purpose of the car and what you expect to receive for your $$$.If you want something fast and reliable you NEED to spend money and not just on the engine.You need to spend money on the ignition,fuel system,exhaust,induction suspension and brakes and safety to get close to what you want.

 

A fast car is not a big HP engine it is a car that has ALL the correctly matched bits from head to sump and everything in between plus the convertor,gearing fuel used,ignition,suspension,tyres (if it has 250hp if will smoke street tyres easy) and above all MONEY.

 

Can't do fast cheap so stop asking the impossible as we have all asked it well before you and found out the hard way fast = $$$ and concessions cos a fast car is not a everyday car.Ask your self what you truly want,research and plan the build,ask all the questions then be prepared to spend the money.No way around it bro...  

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yeah i understand what your saying, just thought there would be straight foward mild work to give a kick, cause at the moment id prefer to drive a bloody sr20, its got shit all pull and dosent like to pull in low rpm to around 2000+, my old nissan sr20 na used to pull revs like crazy!

You are reading this all wrong bro.You can have a 900hp car run 12's or a 400hp car run 11's.Which do you want? A dyno figure is just that and means next to nothing,a ET slip speaks real HP.Which brings us to the true purpose of the car and what you expect to receive for your $$$.If you want something fast and reliable you NEED to spend money and not just on the engine.You need to spend money on the ignition,fuel system,exhaust,induction suspension and brakes and safety to get close to what you want.

 

A fast car is not a big HP engine it is a car that has ALL the correctly matched bits from head to sump and everything in between plus the convertor,gearing fuel used,ignition,suspension,tyres (if it has 250hp if will smoke street tyres easy) and above all MONEY.

 

Can't do fast cheap so stop asking the impossible as we have all asked it well before you and found out the hard way fast = $$$ and concessions cos a fast car is not a everyday car.Ask your self what you truly want,research and plan the build,ask all the questions then be prepared to spend the money.No way around it bro...  

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