[JeZeus]

Following the performance
regulations for the 2WD Open rally class I'll be entering my 2004 Tiburon GT into; for an engine to be turbocharged it must be 2.5L or less.

With the Tiburons V6 engine putting out maybe 200whp (ideal max) with all possible NA mods other than a built block and NOS injection, it will make it difficult to compete with the other NA and turbo vehicles (Which are normally running 225-350hp depending on their weight and restrictions)

With the Tibruon's V6 having a displacement of 2.7L, this means I either have to rebuild the whole engine for NA performance ($$$) or instead reduce the displacement of the engine so it's eligible for use with a turbo (hopefully possible and not as expensive as a full NA build).

To reduce the engines displacement I either have to reduce the cylinder bore and/or reduce the engines stroke. As far as I know, this can be done through the use of cylinder sleeves and custom pistons, or with a crankshaft custom grinded to the right stroke and custom pistons.

The only other option I can think of is using NOS for extra hp, but this doesn't seem too practical for rally racing and I'm not sure if it is even allowed under the regulations/restrictions.

Does anyone know what the easiest and most cost effective route would be? Has a displacement reduction ever been done on a Tiburon V6 before? I'm starting to think I'm mostly SOL with hoping to reduce the displacement without spending $$$, but I figured I'd try asking the forums first.

Any help is greatly appreciated.

Thanks,
Z

 

[chase206]

Your easiest and most cost-effective way is to go find a 2.5L junkyard Delta out of an earlier Hyundai from the late 90s. It's all the same heads and intake for the most part the only difference is either the crank or the bore.

 

[JeZeus]

Your easiest and most cost-effective way is to go find a 2.5L junkyard Delta out of an earlier Hyundai from the late 90s. It's all the same heads and intake for the most part the only difference is either the crank or the bore.

Wow that sounds like the perfect solution. Thanks man, I didn't even know that there was a 2.5L available. With the majority of the parts being shared across the 2 engines that will allow me to have spare parts, and then I can also setup and fine tune the suspension and other misc. items with the 2.7L in the car, while I prep the 2.5L. Thanks again 👌

 

[2tibs]

Same stroke different bore... it’s basically a stroker 2.7... longer stroke bad for na performance but boost loves to make power with long strokes so if your planning on that your going to want to keep the rpms low... the 2.7s love to rev but if you get nice pistons and rods and do a little work I’d say 7000rpm with boost would be alright.. no idea how much they can handle but I’m assuming it would be round the same as the 2.7 since it probably just has a smaller bore.. sounds fun and good luck with all that stuff

 

[chase206]

Same stroke different bore... it’s basically a stroker 2.7... longer stroke bad for na performance but boost loves to make power with long strokes so if your planning on that your going to want to keep the rpms low... the 2.7s love to rev but if you get nice pistons and rods and do a little work I’d say 7000rpm with boost would be alright.. no idea how much they can handle but I’m assuming it would be round the same as the 2.7 since it probably just has a smaller bore.. sounds fun and good luck with all that stuff

Not a stroker actually. The 2.7L is just a bored out 2.5L. Everything else is more or less the same though. The piston speeds will be the same on the 2.5L vs the 2.7L due to the stroke being the same. I've revved my stock rotating assembly 2.7L out to 7500 no problem. It could probably take more but the power tapers off pretty bad at 6500 without bigger cams.

Wow that sounds like the perfect solution. Thanks man, I didn't even know that there was a 2.5L available. With the majority of the parts being shared across the 2 engines that will allow me to have spare parts, and then I can also setup and fine tune the suspension and other misc. items with the 2.7L in the car, while I prep the 2.5L. Thanks again 👌

If you need help with the ECM I'm able to flash and also socket the EEPROM for faster removal and reflashing. Let's say you want more aggressive ignition or a raised revlimiter, I can do all of that.

 

[JeZeus]

Not a stroker actually. The 2.7L is just a bored out 2.5L. Everything else is more or less the same though. The piston speeds will be the same on the 2.5L vs the 2.7L due to the stroke being the same. I've revved my stock rotating assembly 2.7L out to 7500 no problem. It could probably take more but the power tapers off pretty bad at 6500 without bigger cams.



If you need help with the ECM I'm able to flash and also socket the EEPROM for faster removal and reflashing. Let's say you want more aggressive ignition or a raised revlimiter, I can do all of that.

View attachment 136647

I'll be tuning the engine with TunerStudio Ultra (the AutoTuning feature in the Ultra version is so nice for creating base maps) on a Megasquirt MS3 (MS3 instead of MS2 mainly for sequential fuel and spark, and the higher resolution tuning tables), but thanks for the offer!

 

[Rushking19]

I'll be tuning the engine with TunerStudio Ultra (the AutoTuning feature in the Ultra version is so nice for creating base maps) on a Megasquirt MS3 (MS3 instead of MS2 mainly for sequential fuel and spark, and the higher resolution tuning tables), but thanks for the offer!

Only thing is with the 2.5l there's no aftermarket pistons so I would gap the stock rings on the stock pistons bigger and be careful with the tune, then you need to make a custom turbo set up