Im replacing the heads on my 4.0L OHV v-6 in my explorer and i was wandering, i have the 90TM heads and was wandering would the 98TM heads work on my truck and if so would i get any better performance out of them versus the 90TM heads on my truck now???


Cologne V-6 Cylinder Heads<TABLE border=1><TBODY><TR><TH>Head "name" <TH>intake
ports <TH>exhaust
ports <TH>Casting
Number <TH>Comments <TR><TD>2.6 <TD>3 <TD>2 <TD>70TM <TD>Used on 1972-73 US-spec Capri I 2600. Apparently, it is also used on the 2.0 liter version, and I'd guess on the 2.3 as well. Some people like to put these heads on later 2.8 engines. Some people believe that the earlier 2.6 heads flow better. The 2.6 heads make it possible to fit the Kugelfischer fuel injection system used on the Capri RS-2600. These heads will not easily fit on the later 2.8 block however, due to water passage alignment problems.

<TR><TD>Weslake <TD>3 <TD>3 <TD>WRP 151 4001 <TD>Used on 1971-73 Capri RS-2600 race cars. These aluminum heads are extraordinarily rare, and similarly expensive. They will only work with the corresponding Weslake injection intake. Casting number is a Weslake code, not a Ford code. <TR><TD>2.8 non-smog <TD>2 <TD>3 <TD>74TM <TD>Used on 1974 US-spec Capri I. <TR><TD>2.8 smog <TD>2 <TD>3 <TD>75TM <TD>Used on 1976-77 US-spec Capri II. <TR><TD>2.8 European <TD>3 <TD>2 <TD>79TM <TD>Used on 1979-86 European-spec Capri III. <TR><TD>Swaymar <TD>3 <TD>3 <TD>79TM? <TD>A modification of the 2.8 European head, with the exhaust port "un-siamesed". <TR><TD>2.8 <TD>3 <TD>3 <TD>85TM <TD>Used in Sierra XR 4x4 and Scorpio=(Granada MK3 in UK) , circa 1986-87 <TR><TD>2.9 (early) <TD>3 <TD>3 <TD>86TM <TD>Used on 1986-1992 Ford Rangers and Ford Bronco IIs. <TR><TD>2.9 (Scorpio) <TD>3 <TD>3 <TD>86TM <TD>Used on 1989 Ford (Merkur) Scorpios <TR><TD>2.9 (late) <TD>2 <TD>3 <TD>89TM <TD>Used on mid 1988-1992 Ford Rangers and Ford Bronco IIs. <TR><TD>2.9 Cosworth DOHC <TD><TD><TD>? <TD>Used on a few European Ford Scorpios. Many people have wondered whether these DOHC heads could be fitted to a 4.0 block. Sven Pruett has done it, and apparently he even made it work fairly well, but it took an enormous amount of effort to get it to work. Cosworth has also apparently done it with the FBD and FBF engines, but I don't know if these ever made it into production. <TR><TD>4.0 OHV <TD>3 <TD>3 <TD>90TM <TD>Used on Ford Rangers and Explorers. <TR><TD>4.0 OHV <TD>3 <TD>3 <TD>93TM <TD>Used on Ford Rangers and Explorers. Similar to 90TM, but said to be a stronger casting. <TR><TD>4.0 OHV <TD>3 <TD>3 <TD>95TM <TD>Used on Ford Rangers and Explorers. The first of the "Small chamber" heads. Smooth intake port, old style exhaust port. <TR><TD>4.0 OHV <TD>3 <TD>3 <TD>98TM <TD>Used on Ford Rangers and Explorers. A refinement of the 95TM head, it has smooth intake ports, small chambers, and round exhaust ports. <TR><TD>4.0 SOHC <TD>3 <TD>3 <TD>97JM <TD>Single overhead cam version of the 4.0, Used on Ford Rangers, Explorers, and 2005 Mustangs. </TD></TR></TBODY></TABLE>

 

The exhaust ports on the 98TM heads are narrower than they were on the earlier castings. According to the engineers who designed these heads, the smaller ports increased the velocity of the exhaust gasses so they carried more heat down to the catalytic converter which would help the converter “light off" sooner to burn cleaner. With that in mind, it’s probably not a good idea to swap these heads with any of the earlier castings. Also, I think you have a change in the compression ratio due to the smaller chambers, possibly higher than you'd want. A better bet would be the 93TM castings.

 

my goal is to raise the compression ration to about 12:1 but you say these heads will not work on my truck???

 

Not if you wanted to keep your truck in stock or near-stock configuration...but what are your goals with the truck? 12:1 is pretty high compression for a street driven truck. You wouldn't be able to run it on pump gas, that's race fuel territory.

 

my idea is to get the compression ratio as high as i can and imgoing to be runnine 98 octane fuel.... um i want to bump the horsepower up to near 200... the motor stock has like 155 i believe and ive already got the heads off so i figure doign this and running the higher octane fuel should bump me up tosomewhere around 200.... unless you know an easier cheaper way to do this.... cause with the other heads i think i would have tochange my exhaust manifolds out correct?? and mabey my intake??? im not sure... anyways let me know what you think.

 

you'll never get the weak 4L OHV head to live long at 12:1 compression

drop in a late model 4.0L OHC/tranny and PCM
will gain 75 hp and 50 lbs/ft torque with mods