CR bluetop EU

[El_Camino]

Yo! Sounds silly but the question is:

What is the compression ratio of the european bluetops without catalytic convertor?

I ask this, because I saw in some more european magazines CRs of 10:1. Which is maybe a mistake I tought, but an owner of the manual of the car in Germany is confirming that it is 10:1 for the EU models without catalytic convertor in his manual(the book from 1984).

These are the facts so far:


and this

http://www.stud.uni-karlsruhe.de/~urmj/A...03-big.jpg

and this:

http://www.stud.uni-karlsruhe.de/~urmj/A...03-big.jpg

against this:

http://club4ag.com/faq%20and%20tech_page...ations.htm

So... could you also provide arguments for your choice when voting?

[gon]

That’s a good question, Portuguese AE86 don't have catalytic converter, and "Salvador Caetano" ( Portuguese Toyota importer) always said that it has 10:1 compression, but I have some doubt's about that.
I can tell you that for the blue top (18mm pin piston) there are 2 different part numbers for pistons in Toyota, and one is taller than the other, but in the end I can't confirm anything for sure, so I won't vote.
But that is a really good question.

[Knudsen]

Its 10,0:1 with octane 98

I got that directly from the datasheet from Toyota.

[meshin]

My Bluetop without catalytic convertor in AE82 has 9.4:1 ... that's for sure...

[Knudsen]

Well, that could explain the 121hp in AE82 and the 124 in AE86.

I got the complete datasheet specific to my car, and it says 10:1.

[El_Camino]

meshin Wrote:My Bluetop without catalytic convertor in AE82 has 9.4:1 ... that's for sure...

Did you measure it?

Btw. a way to calculate it is, by having the volume of the combustion chamber. Then we know the bore & stroke. Just dont know the volume .

Knudsen - 3 HP difference can be from the ECU too.

[firehawk]

Yes, the documents from the finnish Toyota importer Korpivaara (back in the 80s) also state that the AE86 engine compression ratio is 10.0:1. At least the US models seem to use 9.4:1, on the other hand.

The primary difference seems to be the pistons - 10.0:1 models have a small dome on the middle of the piston which decreases the combustion chamber volume by about 1.6cc when compared to a completely flat piston. The 9.4:1 model, on the other hand, has a very similiarly shaped dish in the middle of the piston. It increases the combustion chamber volume by 1.6cc when compared to a flat piston, and 3.2cc when compared to the domed piston.

Note that I calculated these dome/dish volumes by assuming 39cc as the head combustion chamber volume and a 1.2mm compressed head gasket thickness.

[S.K.]

I have seen in some brochure that:
AE86 have 11:1 and other tells 10:1
AE92 have 10:1
AW11 have 10:1

[Knudsen]

El_Camino Wrote:Knudsen - 3 HP difference can be from the ECU too.

I can only speak for the danish models, and they have all the same type ECU´s.

[El_Camino]

Looks like the 9,4 is a BIG myth ... at least no facts are speaking for it so far