Upgrade Q's

Posted by Lucky on 9/23/2012 to ARD Blog Articles
I received a request from a FF subscriber a week ago about suggested upgrade routes for different models. This subject could be lengthy enough to cover a few blog articles so we’ll keep this focused on the main Volvo models and engine configurations that are most common and frequent in the US market. This week we’ll cover the differences between the LPT and HLP engine blocks. 

The LPT:
Volvo engine configurations are pretty wide spread globally but for us in the US the preferred engine variants for performance are the turbocharged Low Pressure Turbo (LPT) and the High Pressure Turbo (HPT) engines. As the names imply the difference is in the total pressure the turbo is programmed to make relative to the engine configuration it’s bolted up to. LPT motors have a higher initial compression ratio that inclines them toward a lower maximum boost target. LPT motors also tend to have a bit steeper torque curve from this added compression. As such this means total boost is generally less than their HPT counterparts and timing curves tend to be less aggressive as well meaning that the horsepower curves are a bit flatter as compared to the HPT engine. This isn’t to say the LPT engine isn’t a good platform to start from for performance. Upgrading the stock LPT turbo to a larger 16T or 18T isn’t as crazy as you might think. The added compression is a factor but doesn’t prevent these engines from generating some serious performance increases. 

 Case in point: 
 I have a current customer with a 2000 S70 GLT FWD with a 19T installed, and while this car is ME7, which means there are more sensors to help the ECU manage this increase in flow, it’s been a real surprise to see how far we can push the engine without running into detonation as quickly as we expected. Running the 19T at 16psi for over 40K on the odometer since the upgrade and tune, we’ve been very excited to see how much sturdier these engines are than we initially thought. This particular setup isn’t something that I would advise most folks but since he’s local and a friend we’re working together to explore the limits of the LPT blocks. With some water injection and perhaps an intercooler we’re looking to run 18psi on this block later in the fall. 

The HPT: 
With a slightly lower initial compression ratio the HPT block is well suited to higher boost pressures and more aggressive timing curves as the detonation ceiling is naturally higher than the LPT blocks and therefore power development is much different. The typical upgrade path for this engine is an 18T or 19T although the more mild 16T can be a good upgrade for 850 models that have the 15G installed stock. Since both HPT and LPT models use the same intercooler you can surmise that the lower the boost pressure the better job the intercooler does as the boost charge temps don’t rise so high and the flow so much that the intercooler can’t keep up. That’s why as you look for more and more power from these engines you start to have a number of supporting components that need upgrading. 

 At the end of the day each has its value and it’s place in the Volvo world. I for one would not trade my 99XC with 16T and Green tune for an HPT in the same car even if the peak power was higher. I need the additional off the line torque to keep the car feeling nimble and ready to ‘pounce’. At the same time I love going for a drive in the 18T 850 with M4.4 Blue tune I have as well… but for an entirely different reason. Get to know the folks in your local Volvo community so you can get to know the different engines, supporting mods, and driving characteristics that each configuration can provide. That will help you make the performance and upgrade choices that best suit you better than any article can! 

 Not sure what engine you have in your car? VIN will tell you all you need to know to look up the specs on your engine and vehicle model. Use the resources here at MVS to get the info you need about the upgrade path that might be right for you! 

Robert Lucky Arnold
 

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