Porsche boxster 2500 racing

[NGR]

Hi guys,
I have some questions about tuning a 2500cc.

I am running this car for competition..it is so nice to race this car.
Really love it.
Now I like to tune this engine.

And I am curious what is the best thing to do.

I was wandering can I use a cilinderhead head of a 2700cc?
It has the same bore as a 2500cc.
And the inlet ports are bigger.

What can I do more.

Thanks guys

[jluetjen]

Step 1: Read the rule book and technical specifications for the class that you're racing in.
Step 2: Re-read the rule book and the technical specifications for the class that you're racing in.

So that being said -- where are you located in the world and what is the class that you're racing in?

[NGR]

Hi

Thanks .
I read the book already.
Really Nice.
Nut to be honest not detailed enough.

Like does the cilinderhead of a 2.7 fits a 2.5
Or, are The camshaft of a 3.2 ate the same as a 2.7 and 2.5?
Is here somebody who getted 300hp out the 2500cc?

I am from Belgium.
Race in the yountimercup
Bravoracing.be

My personal site NG-Racing.be

Many thnakks👍👍👍👍

[jluetjen]

Unfortunately not as much of the technical information (port diameters, valve sizes, etc) is easily available as it was for the early air-cooled 911. I did a quick search and noticed that the 2.5's and 2.7's use the same intake valve: 99610511105. My experience looking at air-cooled 911s suggests that the valve size is more important for generating air-flow (and thus HP) than the port size. So I'm not sure if just a head-swap is going to net you a whole lot. Especially if you consider that the 2.7 doesn't make that much more HP than the 2.5, and they are both pulling air past the same sized valves.

Given that the 2.7 makes its peak HP at a higher speed (4750 RPM) than the 2.5 (4500 RPM), in spite of it's larger capacity (and using the same intake valves) suggests to me that the camshafts are different. You might want to check that.

Are you racing in the "Platform 4: Touring from 1991 to 2000 -- 4 D 2001cc - 2500cc" class?

Just out of curiosity, I took a look at the technical regulations (thanks to Google translate). It looks like the sections which I underlined below would preclude you swapping out the head for a head from a 2.7. But of course, the decision to do this or not is up to you. But I've seen far too many winning cars get disqualified for technical irregularities, so I would always encourage you to stay within the technical regulations and improve the "nut behind the wheel" before installing illegal parts on a race car. Just my $0.02.

ART. 1: DEFINITIES – OMSCHRIJVING
Original or serial part
A part that has undergone all stages of production, provided and performed by the manufacturer of
the car concerned, and mounted on a car as original.
1.2 Recognized
In possession of a full sporting and technical regulation, approved by a
ASN as a member of the FIA.
1.3 Group bound
Belonging to a brand within the same brand group. (e.g. Jaguar in the FORD group)
1.4 Period specification
“Period specification” means the configuration of the proven model,
after approval by the FIA, that the model actually existed at that time and whose
classification was determined. The participant must provide proof of this (with
homologation sheet, HTP, historical document,…)
Any modification of the “Period Specification” of the vehicle is prohibited, unless expressly
permitted by the provisions of the present regulations relating to the Class of the
car, or one with a statement published in the Bulletin of the FIA ​​regarding the
model of the specific car or the specific pieces or unless imposed in Art 14
(safety) of the Technical Regulations. (e.g.: FIA homologation sheet 3053 concerning a
Porsche ranging from 2.7l to 3.0l)

(This sounds very much like the rule which the SCCA has in the US which basically says "If these rules don't specifically say that you can modify something, YOU CAN'T" (my emphasis)).

ENGINE:
Engine type and position
The engine must be brand specific and must be installed in the original engine compartment.
The position of the engine and of the fire barrier must be respected as shown:
described in Art. 15.2.
For Class 4, the maximum displacement is 2500cc, for naturally aspirated engines.

Engine modifications
Machining, polishing and balancing of engine parts is allowed, on
provided no material is added.
The compression ratio may be altered by adjusting the top surface of the engine block or
cylinder head and/or by eliminating or using a thicker
cylinder head gasket.
Crankshaft, connecting rods, piston and bearings may have a dimension greater than specifications
of the Period. These must be made of the same material type.
The cylinder capacity may be increased by a maximum of 15% compared to the homologation sheet.

materials
▪ The use of magnesium and titanium is prohibited unless used with the original
part.
▪ The use of ceramic or ceramic-coated components is prohibited unless
material is used with the original part.
Exception: the external ceramic treatment of the exhaust.
▪ The use of carbon or composite material is limited to tension-free coatings and
air guides.

Engine block
Class 3
The engine must be brand and model specific and in the original engine compartment
are built-in.
Camshafts and valves of different specification or manufacturer are allowed.
• Class 4
The engine must be brand and model specific and in the original engine compartment
are built-in.
The position of the engine and of the fire barrier must be respected as shown:
described in Art. 15.2.

▪Class 5
Engine block and cylinder head are free but must be brand specific, dating from before
31/12/1999. The number of cylinders must not deviate from the original engine.
5.2.3 Cylinder head
The cylinder head is free, provided that:
- This Period is bound,
- The number of inlet and outlet ports remains unchanged
- The structure of the engine is not changed.
The use of another material (alloy) is permitted

[NGR]

Hi
Many thanks
I race in class 4d.

It ok to change the head of a 2.7, no problem for technical inspection.

So nobody here has experience with swapping the head of a 2.7 to a 2.5?

Dies there will be a timing problem of the distribution?

Thx

[mikefocke]

Wander over to the pit lanes for one of those races and make some friends and ask what they think is legal and necessary to make you competitive.

The number one item is track time with an instructor. The second item is oil pan modifications to keep the engine glued together. The third is weight saving mods within the regulations.

And the most important is safety modifications both to meet the regulations and to keep you safe.

The least important is mods to the engine unless they are for reliability (like the under drive pulley).