289 vs. 302

cjperry81 · Feb 6, 2008

Im looking to make an engine swap in my 66 from the current 200. I have been thinking for a while about what direction i want to go in and at first was debating between a 351 and a 302 but peoples advice led me to the 302 because this is my first swap. Ive been searching for a 5.0 but today came across a good deal on a 289 out of a GT. Could someone give me thier opionion on the two engines. Im not looking to make the car a daily driver but i want plenty of power. I didnt know if you could really upgrade the 289 to get alot of power on a budget. Any advice would be much appreciated.

htwheelz67 · Feb 6, 2008

you can make more power cheaper with a 5.0, 5.0's have forged pistons and roller cam readyto start with so you are ahead from the start.

rbohm · Feb 6, 2008

the difference in power output between a 289 and a 302/5.0 is minimal at best. yes a 302 will make a bit more power given equal mods. the 289 will make its power in a slightly different rpm band, usually 200-300 rpm higher, so if you want as much low end torque as possible, go with the 302. otherwise buy what is available since the only real difference between the engines is the stroke and the rod length.

Hack · Feb 7, 2008

htwheelz67 said:
you can make more power cheaper with a 5.0, 5.0's have forged pistons and roller cam readyto start with so you are ahead from the start.

I agree that a later block already set up for a roller cam is a good idea. The new oil has so little of the metal lubricants that flat tappet cams like. Also there are a lot of people hot rodding their Fox Mustangs, so you can get parts cheaply from them.

D.Hearne · Feb 7, 2008

htwheelz67 said:
5.0's have forged pistons and roller cam readyto start with so you are ahead from the start.

Not true. The vast majority of roller 5.0's do not have forged pistons. Even if they did, forged pistons alone do not make any more power than other pistons

danny clemens · Feb 7, 2008

My vote would go for the 302 since you're starting from scratch. If you already had the 289 I would say go with it. 302s are abundant and can be had cheap. I know they won't make much more power but if it's going to cost the same why not get that little bit extra. The roller 302 would be the best choice if you're looking for a lot of power.

Hack · Feb 7, 2008

D.Hearne said:
Not true. The vast majority of roller 5.0's do not have forged pistons. Even if they did, forged pistons alone do not make any more power than other pistons

I'm not sure why you worded it this way. Yes, only '85-92 Mustang 5.0s have forged pistons. You are right that forged pistons don't MAKE more power, but they can TAKE more power without failing. Forged is a good idea if you are going to run NOS or a blower - or even if you are putting performance head/cam/intake on the motor. The forgings can handle more RPM without failing when compared to castings. They can also better handle detonation from bad gas. The TRWs in the 5.0 aren't that great of forgings, but they are still much better than cast pistons.

One other thing to consider is that you will probably buy a higher mileage block and then bore it. So you probably will need new pistons anyway. The main reason I'd buy a later 5.0 is to be able to run a roller cam.

D.Hearne · Feb 7, 2008

I worded it that way for a good reason. If one wants to limit himself to only those motors out of 5.0 Mustangs ( of which, many have been beat on) and completely over look the thousands of good roller 5.0 cores, so be it. That leaves more for us who know better. Take for instance the 5.0's from the 87-97 pickups and vans. The only parts different in these from the Mustang 5.0's(long block) are the cams and pistons. If you're going to rebuild anyway, you're passing up deals left and right. As for rpm capabilities, that's a moot point. I've had one 5.0 I built using a reman shortblock with Silvolite hypers that was subjected to daily trips to 6500 rpms for over a year and then another 4 months of spins to 7500 and never had issues with the pistons. Regular cast pistons are just as capable. Unless you're going to spray it or huff it, Forged pistons are not a requirement for a motor. As for detonation resistence, that can be avoided simply with better tuning.

rbohm · Feb 7, 2008

cast pistons are fine for a street engine, and even for many strip engines as well. too many people spend money needlessly on forged pistons. if oyu are building a blower motor, and/or spraying nitrous, then by all means pop for forged pistons. otherwise take the time to tune the ignition and fuel curves to avoid detonation.

Hack · Feb 7, 2008

D.Hearne said:
SNIP... As for detonation resistence, that can be avoided simply with better tuning.

I'm sure you read my post and saw that I agree with almost everything you're saying. I have forged pistons in my latest build, but I probably didn't need them. But when my floormat shifted and stuck the throttle wide open - I was happy that a couple bounces off the limiter didn't cause any problems.

The one thing I disagree with is the casual tone you treat detonation resistance with. I think that it's easy to have some detonation and not know it. It's hard to hear some light pinging if you have performance exhaust. I guess I have a little tendency to over-build things. Maybe it's my German ancestry. I'd rather spend a couple hundred extra on nice pistons than figure cast is good enough. Obviously everyone else gets to do whatever they prefer with their own engines.

http://www.network54.com/Forum/119419/thread/1195054526/boat+anchor

Maybe it's recently reading this thread about cast piston failures.

D.Hearne · Feb 7, 2008

Believe me, I've seen what detonation does to cast pistons, seen the same results with forged too.(broken ring lands) And it takes more than a light pinging to make that happen. Cast pistons are also lighter (in general) than forged. Bottom line is, those who keep preaching looking only for the Mustang 5.0's to use are misleading the uninformed. How many are still out there in usable condition 14 years after they left the assembly line ?

htwheelz67 · Feb 7, 2008

I never said forged pistons make more power but if your making power forged pistons are always good no 289 came with them and I have broken stock pistons on 289's before and I can tell you stock pistons nowa days are not as good as stock pistons were from the factory.. A 302 will always make 10-15 hp/tq more than a 289. The 289 will rev a bit more and has an excellent R/S ratio so will tolerate a slight bit more compression on pump gas. Its kinda like comparing a 393 to a 408........408is just better......

D.Hearne · Feb 7, 2008

htwheelz67 said:
I never said forged pistons make more power but if your making power forged pistons are always good no 289 came with them and I have broken stock pistons on 289's before and I can tell you stock pistons nowa days are not as good as stock pistons were from the factory.. A 302 will always make 10-15 hp/tq more than a 289. The 289 will rev a bit more and has an excellent R/S ratio so will tolerate a slight bit more compression on pump gas. Its kinda like comparing a 393 to a 408........408is just better......

The factory pistons today are far and away better than the ones used in the 60's and 70's. I lost track of the number of those that had their missing skirts end up in the oilpan. That was just something you expected to find when tearing those older motors down. Didn't seem to affect the performance either.

Hack · Feb 8, 2008

D.Hearne said:
SNIP.. Bottom line is, those who keep preaching looking only for the Mustang 5.0's to use are misleading the uninformed. How many are still out there in usable condition 14 years after they left the assembly line ?

Yeah, I agree with that completely. If you buy a used engine probably 95% of people will bore it and buy new pistons, so why look for forged? I have a set of forged pistons laying around for that very reason. I found 0.003" taper in the bore and decided I'd best get the block machined.

64point5 · Feb 9, 2008

If you are looking for mustang motors with forged pistons, ther are in the 87-92 mustangs. The 85-86 were not forged and they did not have valve reliefs in the pistons so cam usage is very limited. Regarding the quality of the TRW "factory" pistons, my experience has been that they are excellent. If tuned properly, you will split the factory 5.0 roller block (E7TE casting) long before you hurt those pistons. Have been 9s in the 1/4 with a stock block and rotating assembly from a 88 mustang and it is common to get over 200k miles out of one.

I agree however, that if you do not plan to spray the motor or used forced induction, the forged piston shortblock is unnecessary. It sounds like you are concerned with power however, and we all know how addicting that is. If you don't plan to initially use forced induction you still may decide to later. I would go ahead and use the forged piston SB if it was me.....

289 vs. 302

cjperry81

Member

htwheelz67

Member

rbohm

Hack

D.Hearne

New Member

danny clemens

Member

Hack

D.Hearne

New Member

rbohm

Hack

D.Hearne

New Member

htwheelz67

Member

D.Hearne

New Member

Hack

64point5

New Member

Similar threads

289 vs. 302

Member

Member

New Member

Member

New Member

New Member

Member

New Member

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency