2.7i Pros and Cons

[stormtrooper15]

eta short block with seta pistons

[nando]

True - but even the seta engines with 885 heads don't really end up with that much more power than a B25.

[IronFreak]

I don't think so, it's not a straight displacement increase = more power, and you know that.

the 2.7i doesn't have the same VE as a 2.5. the fact is they both make basically the same peak torque, only the 2.7i does it at a lower RPM. So it has larger displacement, same torque, which means it has to have lower VE. An engine with lower VE N/A will also have lower VE with boost.

It's not going to make a lick of difference in the end. in fact, I'd put my money on the boosted B25.

not all 2.7 were created equal. We don't know if OP has a E or ETA short block.

[jalopi]

blunt said my pipe was too small for his liking.

heh. hehehehe

[nando]

2.7/2.5 is an 8% increase, at a given low rpm you gain a higher % than this though.

I don't think so, it's not a straight displacement increase = more power, and you know that.

the 2.7i doesn't have the same VE as a 2.5. the fact is they both make basically the same peak torque, only the 2.7i does it at a lower RPM. So it has larger displacement, same torque, which means it has to have lower VE. An engine with lower VE N/A will also have lower VE with boost.

It's not going to make a lick of difference in the end. in fact, I'd put my money on the boosted B25.

[EatsHondas]

You do realize that motor in that video was probably 700+hp.....

The car was then wrecked I believe but the heart was saved and it turned into this.......

The Blue Monster

Little fun fact.

Hahaha not at the time no, I didn't!

But the fact that you can squeeze that power from that teeny displacement is incredible.

Gotta hand it to the Swedes.

[digger]

2.7/2.5 is an 8% increase, at a given low rpm you gain a higher % than this though.

[ak-]

it's only 0.2l of displacement - it doesn't really even make that much difference.

if you already have an eta, fine, slapping a B25 head on makes some sense. Pros: it's cheap.

Cons: If you started with a B25, putting in the B27 block is hardly worth the effort. I collected a ton of 2.7i dyno graphs and most of them made the same or less power as a stock B25. They peaked torque a little earlier but really didn't make much more torque (often less) either. The displacement gains are mostly lost in the fact that the pistons don't match the shape of the 885 combustion chamber and you lose almost a full point in compression ratio.

The lower CR for boost doesn't even really make any difference either because the B25 already has a fairly low CR and it works great for boost out of the box. it's going to make what, 10ft/lbs more at 15psi? what's an "assload" of torque? blunt? :p

I don't know Nando, when I went 2.7i (seta internal), from a 2.5i I made roughly 50wtq more on the same PSI (12psi) on the same tune for the first dyno pass before the operator raised the boost controller for some WOT tuning.
Now the car is making 53wtq more than whp at 15psi and the only things changed during the rebuild was an equal length manifold (not sure if it matters much on a 6cyl) and a bigger downpipe (from a 3" to a 3.5") because blunt said my pipe was too small for his liking.

[stormtrooper15]

I know the at least the rod bearings are bad because of severe knocking and shavings in the previous oil and oil filter. Adjusted values and knocking persisted. Used stethoscope on top and bottom of engine and sound is worse near the bottom around the oil pan.

[nando]

when you 2.7i and boost it later on, you will thank the torque gods.

it's only 0.2l of displacement - it doesn't really even make that much difference.

if you already have an eta, fine, slapping a B25 head on makes some sense. Pros: it's cheap.

Cons: If you started with a B25, putting in the B27 block is hardly worth the effort. I collected a ton of 2.7i dyno graphs and most of them made the same or less power as a stock B25. They peaked torque a little earlier but really didn't make much more torque (often less) either. The displacement gains are mostly lost in the fact that the pistons don't match the shape of the 885 combustion chamber and you lose almost a full point in compression ratio.

The lower CR for boost doesn't even really make any difference either because the B25 already has a fairly low CR and it works great for boost out of the box. it's going to make what, 10ft/lbs more at 15psi? what's an "assload" of torque? blunt? :p

[IronFreak]

It also depends on the 2.7, if its from a E-model you're going to loose compression which will drop the HP but you'll see some tq like everyone said. If its a 2.7 seta.....well it'll be more fun.

If you can verify the condition of the 2.7 is in good shape I'd go that route over rebuilding the 2.5. you'll be in it less time and money.

[jalopi]

Since the car is not currently running properly

is it knocking? what makes you say the rod bearings are worn out? how exactly is it not running right?

without more details we can't know whether you're blowing a small issue out of proportion into an engine swap

[redsubdivisions]

when you 2.7i and boost it later on, you will thank the torque gods.

[IronFreak]

Yeah you could say that!

2.7 Turbo Acceleration

You do realize that motor in that video was probably 700+hp.....

The car was then wrecked I believe but the heart was saved and it turned into this.......

The Blue Monster

Little fun fact.

[stormtrooper15]

Would it be more beneficial to get a new 2.5 bottom end than a 2.7 bottom end if everything was the same price?