goal for my 98gt (engine wise)

Mr. Rustypwnz · Sep 10, 2009

ite dudes. Since I've been broke and pretty much just part time lately, I've had lots of time to think of what to do engine wise. so first up is to do a 2v 4.6 no stroking, mark 8 bottom, ported heads, with some wild cams and a edelbrock intake and elbow, of course with all the bolt on crap. next thing is a a 3v swap all the boltons, stock longblock with comp thumpr cams, and a a different intake mani. both of these I could put together around the same price. However I think one would make more than the other. which one would you guys go for?

Mr. Rustypwnz · Sep 10, 2009

or a stock 2v 5.4 with a hardballer mani. and cams. I miss my friend torque

40oz · Sep 10, 2009

Mr. Rustypwnz said:
or a stock 2v 5.4 with a hardballer mani. and cams. I miss my friend torque

And then you'll have a fine engine to tow a boat with :/

An overhead cam engine shines at higher rpms. The reason that is good is because it gives you a broader powerband and top end power. Torque is moved up top instead of dying off above 4000 rpms. If all you want is to do smoky burnouts at stop lights, buy a truck. They'll do it like they were born for it, because they were. On the other hand, heads and cams and other mods that increase the production of torque at higher rpms makes for a better sports car engine, because it can actually accelerate out of the corner.

Think about it - two cars exactly the same except one engine falls on it's face at 4000 rpms while the other is just getting going at that rpm. With the same trans, the second higher rpm machine is much faster in any kind of race because it doesn't die in 4th at 90 miles an hour. Drive a tractor if you want, I'll take an overhead cam V8 that isn't trying to be a diesel truck engine.

To the OP- Go with the 2v with heads and cam. The Mark VIII block idea is great for the weight savings and stronger bottom end, just notch the pistons so you can run whatever cam is best with a top rpm of 7000-8000 rpms. It'll sound great spinning that fast, make a ton of power that is actually useful on a track or strip, and losing a bit of weight up front will only improve the car in every way.

CobraRed_96_GT · Sep 11, 2009

How is a Mk VIII have a stonger bottom end? And why in the heck do you need to rev to 7-8krpm?
Keep in minf for a 3V swap the VVT solenoid and fly by wire throttle you'll need to deal with. Def need to swap over A LOT of stuff.

Mr. Rustypwnz · Sep 11, 2009

you don't need to swap the vct stuff if I go that route ill get phasers an 03 cobra throttle body and the rest of the harness will plug right up. im not afraid to modify stuff to make it work. but keep the input flowin

jomull55 · Sep 11, 2009

CobraRed_96_GT said:
How is a Mk VIII have a stonger bottom end? And why in the heck do you need to rev to 7-8krpm?
Keep in minf for a 3V swap the VVT solenoid and fly by wire throttle you'll need to deal with. Def need to swap over A LOT of stuff.

Mk VIII bottom end is a teksid....

stangGT97 · Sep 11, 2009

I would imagine he's interested in the Teksid block. Stock Mark VIII rods and pistons wouldn't be any better than the stock GT internals.

ninjastang125 · Sep 11, 2009

i am putting together the mark 8 block with the ported 2v heads and you have a little more work then what you think. the swirl valve on the heads have to be grinded off so you will be able to run pump gas. if you dont have that done your comp. ratio will be like 12.8 to 1 and will be running race fuel. the wildest cam you can run is one with a 550 lift unless you notch the pistons. they have six bolt cranks so if you have a 8 bolt fly wheel as i did you will have to get another one. then after all this you have to get dynoed. the lowest price i could find around here in md is 650 with a sct xcal. but good luck with the swap of your choice.

CobraRed_96_GT · Sep 11, 2009

jomull55 said:
Mk VIII bottom end is a teksid....

Bottom end implies the internals i.e. cranks/rods/pistons. Block would refer to the teksid, shortblock would be the internals+block and longblock is shortblock+heads+valvetrain+timing bits

jomull55 · Sep 11, 2009

CobraRed_96_GT said:
Bottom end implies the internals i.e. cranks/rods/pistons. Block would refer to the teksid, shortblock would be the internals+block and longblock is shortblock+heads+valvetrain+timing bits

you are correct, but if he did get the bottom end and blew it up he would have a good block to start from.

I figured that was his reasoning.

CobraRed_96_GT · Sep 11, 2009

jomull55 said:
you are correct, but if he did get the bottom end and blew it up he would have a good block to start from.

I figured that was his reasoning.

That's wierd logic. Who installs a shortblock so that when it blows up the block is still useful. Honestly, just build the teksid with forged internals while you do whatever to your current set-up. Swapping in a teksid in place of ur 98 gt block would be doing you little good for all the labor it would take. I think somewhere someone just assumed Mk VIII's were more stout.

Furthermore, saying that shortlbock is good for power due to the block doesn't make much sense either. An iron block will still be tougher in the end - 03 cobras use our same block (+ clearence for 8 crank counterweights). The Teksid is just incredibly strong for an aluminum block. But it's a moot point anyways, only time you need to start worrying about block strength in modulars is like 800rwhp+.

40oz · Sep 11, 2009

the Teksid block is stronger than the iron block, but the main advantage is weight. It's ~70 lbs. lighter, depending on where you look.

And as far as the internals go, Cobras got a forged crank while GT's and Marks had a cast crank. They all have the same rods and the only difference in pistons is dish, which would have to be dealt with if one were to use the shortblock out of a Mark VIII.

The main argument (besides cost) for using an iron block is the fact that iron blocks tend to make more power, all else being equal, by virtue of the iron keeping the combustion chamber temps more consistent. I think it has to do with the different heat-holding qualities of aluminum and cast iron. I'm not aware of the precise differences but like anything else, the more power you are making the more impact little differences can make. If there is a ten horsepower difference at ~400 hp and the iron block is cheaper to produce, why wouldn't Ford use it instead of the expensive aluminum option?

The OP would be well-served to use a Teksid block just for the weight savings, because the strength differences are irrelevant for NA power levels. And so as long as we are just day-dreaming, why NOT go with a Mk VIII block

CobraRed_96_GT · Sep 11, 2009

That's the first I've head of the teksid being stronger than iron, i realize the 6 bolt main eliminates more walk - but the iron is supposed to hold against integrity failure longer. From what I've head 1000-1200 is teksid and iron is around there at 1200+ in factory form.

My point was that for the labor involved, taking out ur 98 GT shortblock and putting in a Mk VIII is not worth it for the differences.

40oz · Sep 11, 2009

From Sean Hyland's "High Performance Mustang Builder's Guide - 1994-2004" (published by Cartech):
"Where the stock 5.0L block was prone to failure at over 600 hp, the production 4.6L iron block has been reliable at 900 hp, and the 4.6L aluminum block is capable of 1,600 hp! No production North American V-8 block I am aware of is in this league."

Link: http://www.cartechbooks.com/vstore/...bjectGroup_ID=231&CATID=13&DID=6&chapter=4280

And Hyland isn't the only one saying it or doing it. But that just goes to show the strength differences are really moot for most of us. The weight differences on the other hand can be relevant. But I have no idea what kind of work is involved in the swap.

CobraRed_96_GT · Sep 11, 2009

I know the iron block is capable over 1000hp, that's for sure. But never heard 1600 from the stock teksid set-up. That's impressive.

Mr. Rustypwnz · Sep 12, 2009

wow didn't know bout the comp ratio with the mark bottom end. I do like compression though. I've had an 11 to 1 5.0 and it ripped! im sure a 4.6 with 12 to 1 would be a lot of fun although id rather have like 11 to 1.

ninjastang125 · Sep 12, 2009

im almost done with the build and will give you dyno numbers in about a month if you wait that long.

Mr. Rustypwnz · Sep 12, 2009

sounds good I bet it will be a beast.

ninjastang125 · Sep 13, 2009

hope so i got the heads back yesterday and put them on today and tried to put it in time and i keep get ptv problems. anyone on here have a write up on putting these motors back in time? but a good friend of mine ran a similar set up but had 3.73s,stock air intake, stock plenum, stock flywheel ran 12.0 at 112 so hoping to run someting close to that. he dynoed at 315 to the wheel

StangYellow · Sep 18, 2009

40oz said:
And then you'll have a fine engine to tow a boat with :/

An overhead cam engine shines at higher rpms. The reason that is good is because it gives you a broader powerband and top end power. Torque is moved up top instead of dying off above 4000 rpms. If all you want is to do smoky burnouts at stop lights, buy a truck.

Drive a tractor if you want, I'll take an overhead cam V8 that isn't trying to be a diesel truck engine.

.

The guy is building an engine from scratch here. If he wants the extra cubes from a 5.4L (which is ALSO an OHC engine), let him do so. There are plenty of aftermarket cams, heads, and upper plenums to get rid of this "4000rpm" plateau you speak of. Telling a guy not to buy a 5.4 because its a truck engine is not good advice.

goal for my 98gt (engine wise)

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