Crustang to Mustang
Well-known member
What is the performance gain of bolting a crossflow head on a pre-crossflow block?
250ci Crossflow Head on a Pre-Crossflow 250ci HP Gain
- Thread starter Crustang to Mustang
- Start date
If you read the artlcle about rebuilding and installing a 250 Crossflow in a 66 Mustang you can get an idea of the performance gain;
fordsix.com
Here's and excerpt:
"I'm not sure if we hit the 200 hp target, but we are certainly very close. The car will incinerate the tires in first gear, and wheel spin in second is no problem. The first test drive, we "accidentally" lit up the tires in third on some damp pavement. A couple of impromptu runs to 60 netted us some times between 7-8 seconds - very quick! A locker would be nice to have now!"
This is with EFI and the banana intake which is somewhat restrictive for a 250.
Australian 250 Crossflow Swap
The 250 Falcon engine with integral manifold is limited in performance due to the restrictive nature of the cylinder head. To get the most out of it requires radical modifications to improve both intake and exhaust flow. Several rodders have...
fordsix.com
Here's and excerpt:
"I'm not sure if we hit the 200 hp target, but we are certainly very close. The car will incinerate the tires in first gear, and wheel spin in second is no problem. The first test drive, we "accidentally" lit up the tires in third on some damp pavement. A couple of impromptu runs to 60 netted us some times between 7-8 seconds - very quick! A locker would be nice to have now!"
This is with EFI and the banana intake which is somewhat restrictive for a 250.
1980 AUS Fairmont Ghia 1 bbl Crossflow 4.1 liter, 126 hp net. 18.5 second quarter mile as an automatic. 108 mph top speed, 27 US Mpg at 62 mph.
1980 USA Granada Ghia 1bbl non Crossflow 4.1 liter, 99 hp net. 20.7 second quarter mile as an automatic. 95 mph top speed, 23 US mpg at 55 mph.
So 27 extra HP, 13 mph more top speed, more than 4 US mpg better fuel consumption. From 1976 to October 1980, (the last year of the 103 HP net Iron non cross flow in Falcons and Fairmonts in Australia, until the introduction of the aluminum headed cross flow) , the city and highway fuel consumption dropped 20%.
Key concepts. When you get a 27% power boost and a similar fuel economy improvement, it's because not just the air flow of the whole engine combination is improved, it's combustion efficiency and reduced requirement to be always giving it death on the road. Those years, they used the same size 1.3 inch Venturi 1bbl carb, Carter or Bendix Technico, same 195 CFM flow. Same 256 intake duration cam with lift difference only be suse the Cross flow uses a 1.73 rocker instead of 1.5 ratio as on the Log head
The total over the log head intake CFM improvement at 400 thou valve lift was 125 CFM to 145 CFM, just 16% more peak flow, but at lower lifts which happen twice as much, the flow improvement were far greater.
This isn't a pro Cross flow rant. The same improvements can be made with similar flow efficiency improvements, either through better carburetion ( not discussed) or through head porting, rocker ratio or exhaust flow improvements.
1980 USA Granada Ghia 1bbl non Crossflow 4.1 liter, 99 hp net. 20.7 second quarter mile as an automatic. 95 mph top speed, 23 US mpg at 55 mph.
So 27 extra HP, 13 mph more top speed, more than 4 US mpg better fuel consumption. From 1976 to October 1980, (the last year of the 103 HP net Iron non cross flow in Falcons and Fairmonts in Australia, until the introduction of the aluminum headed cross flow) , the city and highway fuel consumption dropped 20%.
Key concepts. When you get a 27% power boost and a similar fuel economy improvement, it's because not just the air flow of the whole engine combination is improved, it's combustion efficiency and reduced requirement to be always giving it death on the road. Those years, they used the same size 1.3 inch Venturi 1bbl carb, Carter or Bendix Technico, same 195 CFM flow. Same 256 intake duration cam with lift difference only be suse the Cross flow uses a 1.73 rocker instead of 1.5 ratio as on the Log head
The total over the log head intake CFM improvement at 400 thou valve lift was 125 CFM to 145 CFM, just 16% more peak flow, but at lower lifts which happen twice as much, the flow improvement were far greater.
This isn't a pro Cross flow rant. The same improvements can be made with similar flow efficiency improvements, either through better carburetion ( not discussed) or through head porting, rocker ratio or exhaust flow improvements.
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And adding to that, the 200ci alloy head2 in Xd-e was rated at 88kw net(118bhp), the earlier precross 200 would have had 85bhp if it was lucky. I drove the alloy head 200s when I worked for telecom Australia way back in the early 80s, they went about as good as a pre 250, and lower fuel usage. So the gain with the crossflow head is quite a bit. the 250 crossflow EFI was very close in power to the 302 Geelong V8!
Myself and a guy who called himself JD got involved with Jack Collins way back, i was still working and living in Perth, JD helped him a lot getting two engines to jack via sea frieght. He rang me a couple of times from Orlando. It all started off talking about 250-2v heads. Anyway the crossflow is a big gain over the old iron heads preX. And yes I have one or three.
Like Europe, the Australian engines ran on 97 octane leaded gas rather than 87 octane regular unleaded, but that's a universal deep drop in percentage terms apples for apples of 27% in most cases.
In the case of the 5.8 liter Ford's, the USA HP drop could be up to 50% less peak power.
Ford USA did it on purpose to ensure mpg ratings stayed the same, and that if the EPA performed Random Verification Emissions Testing, Ford, like all other auto makers, didn't want to have an "Emissions not Obtained" fine leveled against itself. The technology existed to do significantly better in the USA, but Ford didn't even try, especially with the 3.3 and 4.1 liter in line sixes.
The exception was for the Dual exhaust Police Interceptor HO 351 Windsor, a very strong Feedback Variable Venturi 2bbl engine. Still only 174 hp net, verses 200 or 216 HP for the single exhaust 1980 Australia LTD and dual exhaust Bronco XLT 5.8 V8s.
In 1984 to 1986, once Ford USA got it's head around the lead free fuels low octane rating, and figured out how to get that 27 % lost power back without a mileage penalty, High Swirl Combustion engines, like the 2.3 Tempo four, based on the 3.3 in line six, well, it , made exactly as much power as the in line 3.3 did, without having to re-engineer the cylinder head for Aluminum construction or cross flow valves.
The technology existed to match European and Australian HP and economy levels in 1976. Ford's direct injection 5.8 liter PROCO engine, and in 1978, with the Ford Honda 2.3 liter CVH co-operative engine. Dearborn ditched both those when it calculated the cost of putting them into production, so it decided to spend no money on new engine design, and instead, added the Electronic Engine Control IV computer and integrated Spout Out Thin Film Ignition Electronic Spark Control. In Australia, the 1986 91 Octane 3.3 and 4.1 cross flow engines made almost exactly the same power as the 97 octane engines, despite having to match tighter emissions regulations with 2 way catalyst exhausts.
In a situation where your 250 engine won't be emissions tested, You have two choices.
1. Improve the engine management, to cope with the common 91 or 93 octane gas, and get that 27 % power gain gain by good old fashioned 1960s GT techniques..Exhaust, cam, Compression, maybe a Carb upgrade and stock cylinder head modifications
or
2. Radically improve the efficiency of the cylinder head casting, using a better, more modern cylinder head.
Or maybee both.
As a little aside, here is how much Ford's 1963 to 1980 engines lost in power.
"Ford USA rated the 1978 European Capri Cologne 2.8 liter 135 hp 2.8 2bbl at 104 or 109 hp in the 1979 Mercury Capri and Ford Mustang, and just 93 HP net in the optional 1980 Pinto and Bobcat 2.8. The HP loss was due to different cylinder heads, various cat back single exhausts, Motorcraft carb, Duraspark ignition and downgraded compression ratio changes, yet it still had the same cam timing as the European engine. The 3.3 liter Ford in line six strated as up to 125 HP gross in 1963, then glided down to 115 HP gross in 1971. 83 hp net in 1972, 72 hp at the wheels in 1975 ( Ford didn't supply flywheel figures that year). Then 85-87 hp from 1976 to 1983 for the California market, but it was 91-95 hp for some manual versions.Truly the greatest Door stop Ford made. With the exception of the side valve Ford Flathead (65 to 85 hp gross) from 3.6 liter V8, one of the lowest gasoline hp per liter modern engines. The Truck and Van California market 136 HP 351M for 1982 was a tie for net HP per liter. FoMoCo , BeayBeah...And You thought the 1929-1937 US depression was bad? No comparison to the Malaise Era 3.3/4.1 liter and 5.8 in line Fords! As has been stated, the reason was that as soon as the CAFE era started, Ford USA decided to restrict the carburetion, exhaust, compression ratios and ignition advance.
Ford in Australia, the Net HP for a 1980 Ford 3.3, 27 hp extra at 114 hp net. 4.1, 27 hp extra net at 126 hp. 302, 59 hp extra net, 2bbl 129hp verses Australian 4bbl 188 hp.US 351 2bbls, 136 hp 351M, or 145, or 174HP 351W verses Australian 200 or 216 HP 351 C 4bbl. Some percentage figure power losses, like the Truck 351M and Pinto 2.8, were 45 to 58% lower than the same European or Australian counter parts. Be glad you don't have one of those engines!"
In the case of the 5.8 liter Ford's, the USA HP drop could be up to 50% less peak power.
Ford USA did it on purpose to ensure mpg ratings stayed the same, and that if the EPA performed Random Verification Emissions Testing, Ford, like all other auto makers, didn't want to have an "Emissions not Obtained" fine leveled against itself. The technology existed to do significantly better in the USA, but Ford didn't even try, especially with the 3.3 and 4.1 liter in line sixes.
The exception was for the Dual exhaust Police Interceptor HO 351 Windsor, a very strong Feedback Variable Venturi 2bbl engine. Still only 174 hp net, verses 200 or 216 HP for the single exhaust 1980 Australia LTD and dual exhaust Bronco XLT 5.8 V8s.
In 1984 to 1986, once Ford USA got it's head around the lead free fuels low octane rating, and figured out how to get that 27 % lost power back without a mileage penalty, High Swirl Combustion engines, like the 2.3 Tempo four, based on the 3.3 in line six, well, it , made exactly as much power as the in line 3.3 did, without having to re-engineer the cylinder head for Aluminum construction or cross flow valves.
The technology existed to match European and Australian HP and economy levels in 1976. Ford's direct injection 5.8 liter PROCO engine, and in 1978, with the Ford Honda 2.3 liter CVH co-operative engine. Dearborn ditched both those when it calculated the cost of putting them into production, so it decided to spend no money on new engine design, and instead, added the Electronic Engine Control IV computer and integrated Spout Out Thin Film Ignition Electronic Spark Control. In Australia, the 1986 91 Octane 3.3 and 4.1 cross flow engines made almost exactly the same power as the 97 octane engines, despite having to match tighter emissions regulations with 2 way catalyst exhausts.
In a situation where your 250 engine won't be emissions tested, You have two choices.
1. Improve the engine management, to cope with the common 91 or 93 octane gas, and get that 27 % power gain gain by good old fashioned 1960s GT techniques..Exhaust, cam, Compression, maybe a Carb upgrade and stock cylinder head modifications
or
2. Radically improve the efficiency of the cylinder head casting, using a better, more modern cylinder head.
Or maybee both.
As a little aside, here is how much Ford's 1963 to 1980 engines lost in power.
"Ford USA rated the 1978 European Capri Cologne 2.8 liter 135 hp 2.8 2bbl at 104 or 109 hp in the 1979 Mercury Capri and Ford Mustang, and just 93 HP net in the optional 1980 Pinto and Bobcat 2.8. The HP loss was due to different cylinder heads, various cat back single exhausts, Motorcraft carb, Duraspark ignition and downgraded compression ratio changes, yet it still had the same cam timing as the European engine. The 3.3 liter Ford in line six strated as up to 125 HP gross in 1963, then glided down to 115 HP gross in 1971. 83 hp net in 1972, 72 hp at the wheels in 1975 ( Ford didn't supply flywheel figures that year). Then 85-87 hp from 1976 to 1983 for the California market, but it was 91-95 hp for some manual versions.Truly the greatest Door stop Ford made. With the exception of the side valve Ford Flathead (65 to 85 hp gross) from 3.6 liter V8, one of the lowest gasoline hp per liter modern engines. The Truck and Van California market 136 HP 351M for 1982 was a tie for net HP per liter. FoMoCo , BeayBeah...And You thought the 1929-1937 US depression was bad? No comparison to the Malaise Era 3.3/4.1 liter and 5.8 in line Fords! As has been stated, the reason was that as soon as the CAFE era started, Ford USA decided to restrict the carburetion, exhaust, compression ratios and ignition advance.
Ford in Australia, the Net HP for a 1980 Ford 3.3, 27 hp extra at 114 hp net. 4.1, 27 hp extra net at 126 hp. 302, 59 hp extra net, 2bbl 129hp verses Australian 4bbl 188 hp.US 351 2bbls, 136 hp 351M, or 145, or 174HP 351W verses Australian 200 or 216 HP 351 C 4bbl. Some percentage figure power losses, like the Truck 351M and Pinto 2.8, were 45 to 58% lower than the same European or Australian counter parts. Be glad you don't have one of those engines!"
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