Tuning why wont a 1.2 8v in a mpi sei give 75hp???

[tony811976]

im a little confused with the mpi sei and punto 75.


the most done conversion is to ditch the 1.1 short block and put in the 1.2 longer stroke engine.

my question is from another thread. if the punto 75 is 1.2 8v mpi why doesnt the sei put out 75hp when this conversion is done.

some have suggested spi to mpi was purely emission reasons and no power increase.

where is the power hiding? so if this is right will i have to fit a p75 loom and ecu like the p85 conversion

 

[woj]

Mostly the head / cam from what I know. That is, put a P75 head on your SPI engine incl. ECU and you will get a proper kick

 

[tony811976]

i think the heads the same. can someone confirm the size of valves mpi sei to p75

is the cam the extra 15hp alone? or a better map/ injectors /fuel pressure

if i fit a p75 lump into an sei mpi will it give me 75hp or will i have to run the punto ecu

 

[ycming]

The P75 bores on the inlet is much better shaped. Am sure craig (can;t remember his usename), explained in one of his blog!

Ming

 

[tony811976]

ok so a complete p75 engine and manifold(if it fits) running on mpi sei setup will give the 75hp?


so the extra 15hp is all in the headwork/manifold and cam, not just the move from spi to mpi

what im worried about is going to the effort of fitting a p75 lump fitting all the sei stuff to it and only getting 60hp due to emssion regs

can you see where im coming from or am i getting totally confunded

 

[cc1]

If you fit the 75 engine you need to remap the 1.1 ecu or fit the 75 one to make full use of the extra capacity.
It's all about efficiency. How much fuel/air you can get in. How much you can burn, And how well you can get the gases out.
You can easily exceed 75 bhp with an 1100 enginge if go about it the right way.

 

[Fiatseicento2002]

i Thought the 1.2 75 unit was 16v?

 

[cc1]

i Thought the 1.2 75 unit was 16v?

The Punto 75 is 8V with 75Hp, whilst the 16V has about 85Hp.
The Brava has 80Hp.

 

[tony811976]

fuel pressure is higher. injectors have different resistance.

so i think i have all i need.

fitting a 1.2 mpi punto 75 engine into a sei will not give you 75hp you need

you need to use the fuel pump and ecu too

 

[Jay_b]

I have just done this conversion to my MPI.
I ended up using the MPI head and inlet manifold because the P75 inlet manifold fouls on the back of the engine bay and the MPI inlet manifold has differant shape ports to the P75 head because of how far forward the injectors are sat.

Hope these pics help, there are some more in my gallery

 

[Todger182]

I still need to test my spare grande inlet, but that requires removal of the deadening (that i'm pretty sure of).

Thanks

 

[arc]

it's cam, head, inlet manifold, exhaust manifold, mapping and a slightly higher CR that all work together for that extra 15bhp.

 

[tony811976]

it's cam, head, inlet manifold, exhaust manifold, mapping and a slightly higher CR that all work together for that extra 15bhp.

this is where i was going, thanks.

si its confirmed. fitting a 1.2 into a mpi will not give you the 75hp expected as the punto75, as with the punto 85 everything needs to be swapped over to benefit.