paddyscoob

iTrader: (1)

Hi guys what's your opinion on these engines? Which one is best?

Shaun

Depends what the context of "best" is.

paddyscoob

iTrader: (1)

If you had the choice which one would you choose and why?

ditchmyster

iTrader: (7)

Depends who builds it, what it's used for and how it's treated.

stonejedi

iTrader: (51)

2.1 for me out of the two,but as above depends on the quality of build,component parts used etc...SJ.

domino46

For a track car I have a 2.1 so I can Rev the nuts off it , for a road car i have a 2.5 so I don't have to rev the nuts off it lol

Shaun

What are you going to be using the car for and how much power do you intend in achieving?

wms-racing

Thats pretty much the long and short of it, I build loads of both and spend alot of time chatting to Custmers who are trying to make this decision. Depending on the max power you want to run, you can up the compression on the 2.1 to impove spool.

Alan Jeffery

He isn't wrong..
Basically, the 2.5 offers better torque, but the 2.1 can take more stick being inherently more resilient due to the block design.

Primeiro

What model car do you have & what is the plans?

paddyscoob

iTrader: (1)

its road car. looking 400 to 450.

domino46

And it's one of your early 2.1's I Rev the nuts off and still going strong after many years of abuse and track days

Primeiro

Get a CDB & go 2.1 if you can.

But consider a 2.5 for road use as in those conditions the extra torque makes a very flexible power band for the road.

All the best with it.

Mus

iTrader: (2)

a 2.1 would still have good spool at that power level but a 2.5 would be more suitable imho specially if it's used more on the road.

Deanamoore

I have been advised to go 2.5 forged.i stroked my old bugeye.this time I have a type r shell.its going to be a fast road car with the odd track day.around 450 bhp.so for the spool up on the road they say 2.5 forged everyday.but we will find out once I have drove it to compare the to.this was advised by the last specialist that worked on my bug.not just a man in a pub hope this helps

legacy_gtb

iTrader: (3)

2.5 for that power and a road car id say, as the 2.1 build envolves block work, where as the 2.5 would just need forged pistons which can be done by someone who knows what theyre doing without splitting the block.

Primeiro

Although I am sure people have I would not advise that power/torque on standard rods so would be a full build.

2.5 would advise pinning decks, match heights, correct bore clearance, stud conversion full debur & correct spec build.

Only difference over a CDB reg machining is the rear thrust so not a lot in between both.

Any advise we are all here to help.

ditchmyster

iTrader: (7)

I thought about this recently, for me it came down to the psychology of it.

If I went 2.5L I'd always be watching the temp gauge, they run about 10 degrees hotter or at least the one I've spent a bit of time around does, so for me that means less playtime and always having in the back of my mind that even built well there's a risk.

Also when it comes to "playtime" I want to kick the **** out of it without a care in the world and feel that rush of adrenalin, the 2.5L kind of blunts that for me a little, A) See previous paragraph, B) It just lacks that feeling of urgency.

Don't get me wrong, your still moving rapidly in the 2.5L but it's missing the raving banshee aspect, and did I mention the back of my mind thing.

So yeah you guessed it 2.1L stroker with CDB for me please sir.

daddyd

a low temp thermostat should fix that, it's a low cost part, so certainly worth it.