How to spot a 2.7 engine?

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Racing Tortoise
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How to spot a 2.7 engine?

Post by Racing Tortoise »

Does anyone know how you can actually distinguish a normal 2.5 engine from any of the many 2.7 conversions that have been offered over time? I.e., without paperwork, how can you verify someone's claim that a car has a 2.7?

I guess you could rolling-road it, but apart from that??

Cheers for any guidance.
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Holland Harry
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Post by Holland Harry »

Hi RT,

Mine is a 3.0l but from the outside of the engine it looks identical to the standard 2.5l. The only difference is when you put the trottle down. Apart from the paperwork you cannot see the difference IMO.

You could also say that the advantage is that it looks like the original but drive much better.

Here is is pic of a standard 2.5l;
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And here two of my 3.0l;
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Jet
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Post by Jet »

Practically impossible I would imagine, but the tuner will have a record, run the Chassis # and registration through their DB, something must show up and I believe some of them stamp the block somewhere for future identification.
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Racing Tortoise
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Post by Racing Tortoise »

Cheers. Not easy then!!

Seems dyno'ing is the way to go then.
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Post by Jet »

RacingTeatray wrote:Cheers. Not easy then!!

Seems dyno'ing is the way to go then.
What are you up to TT, got something up your sleeve? Do tell.
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Re: How to spot a 2.7 engine?

Post by sfh3l »

[quote="RacingTeatray"]Does anyone know how you can actually distinguish a normal 2.5 engine from any of the many 2.7 conversions that have been offered over time? I.e., without paperwork, how can you verify someone's claim that a car has a 2.7?quote]

Err.......try chasing it in a 2.5!
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Racing Tortoise
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Post by Racing Tortoise »

Jet wrote:
RacingTeatray wrote:Cheers. Not easy then!!

Seems dyno'ing is the way to go then.
What are you up to TT, got something up your sleeve? Do tell.
No, it was just that I was asked the other day by Mark of Munich Legends whether mine was a 2.7. He'd had to drive it over to the bodyshop and back, and had found it considerably perkier than the average Z1 in his experience (and they've got a turbo one on sale at the moment). He recalled that it used to have the Lorenz quad-exit exhaust and that was what prompted him to wonder that was all Lorenz had done to it.

I didn't buy it as anything other than a 2.5 and, frankly, as it's the only Z1 I've ever driven, I wouldn't know either way whether it feels especially quick or not. I've not studied the car's history file closely as it's all in German pre-1997 but nevertheless I've not seen any invoices for the exhaust or anything else tuning-related.

So I guess putting it on a rolling road is the only way I'll ever know. Maybe it's just particularly healthy.
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felix
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Post by felix »

On a 4 valve engine with a central spark plug you can take a plug out and measure the stroke but on a 2 valve engine that method is difficult to use reliably.
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Post by Budget M3 »

Not sure what the euro-tuners use to get to 2.7l, but here in the US, there are a lot of E30 shade-tree mechanics that have made this conversion. It usually starts with a US-spec E30 325e (e for eta) which was a short stroke, low revving engine. If one simply changed the head to a 325i head of similar vintage...wham...you now have a high revving 2.7l pushing 200hp at the crank. If this method was used, then the block and head would have different serial numbers.

I would guess most of the euro tuners, however, simply changed cams and a few other internal parts which would make it impossible to detect a 2.7 without pulling at least the top of the engine apart...
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Post by felix »

Actually the 325e and 528e used a longer stroke crank than than the 325i; 81mm vs 75mm. They both have the same 84mm bore. And the Z1 uses a different variant of the M20 block (same as the 325ix) so a conversion would have to be just be a crank swap.
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Post by estocks »

Surey 0.2L doesn't make that much of a power difference? A well serviced 2.5 could keep up with a rough 2.7 I reckon.
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Post by felix »

There's no replacement for displacement. The longer stroke boosts the torque and most 2.7 conversions done by the tuners will have a sportier cam to boost the top end. A crude calculation - 8% more displacement adds 8% bhp (14 bhp) plus 10 from a cam and 10 from more aggressive timing (requiring premium fuel) and you're at 202.
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Post by Budget M3 »

felix wrote:Actually the 325e and 528e used a longer stroke crank than than the 325i; 81mm vs 75mm. They both have the same 84mm bore. And the Z1 uses a different variant of the M20 block (same as the 325ix) so a conversion would have to be just be a crank swap.
You are correct, sir...I should have said long stroke. The point is that the 325e engine starts out as a 2.7 and when you add the 325i (or iX) head with cam you get a "proper" 2.7 engine without the need to change the crank. I owned a 325e at one time and would have killed for the 325i head/cam combination. In stock form, the d@m! 325e would redline at only 4500 rpm! and made only ~125hp!!
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Post by a1z1 »

RacingTeatray wrote:Cheers. Not easy then!!

I was asked the other day by Mark of Munich Legends whether mine was a 2.7. He'd had to drive it over to the bodyshop and back, and had found it considerably perkier than the average Z1 in his experience (and they've got a turbo one on sale at the moment). He recalled that it used to have the Lorenz quad-exit exhaust and that was what prompted him to wonder that was all Lorenz had done to it.
On Hartge 2.7 conversions they used a different ecu which was stamped Hartge.Hartge cams are also labeled, i don't know if AC or Lorenz marked theres as well.

Perhaps it just sounds perkier :D :D

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