Advice needed for higher RPM engine build

[Rob-bb]

Hi, I am building a Nissan VK45DE 4.5 liter V8 engine, and I am looking for a list of things I should look into to build for higher RPM. I am looking at around the 8500 to 9000 rpm range, but want some safety margin. The engine will be NA but I want to add a centrifugal supercharger in a year or two. Factory redline is 6700, but it runs fine to 7500rpm. Car use is street legal for circuit track with some drag strip, but the 'street use' will be limited.

Things that I think of are oil pressure, flow and cavitation. An electric water pump will solve the coolant cavitation issue. The torque converter at those RPM, will it have issues?

What other things should I be investigating?

[BLSTIC]

What's the oil pump housing and pickup like?

I'd imagine that there are gains to be had in cleaning up edges of machined surfaces, castings etc. Make sure the pickup is correctly sized for the new application (can't help you with the sizing, I just know you've changed the pump speed by about 35%). You could detail the transmission pickup in the same way.

Cavitation is as much about restriction on the inlet as it is pump design.

Converter on a circuit track car? I hope you have a comically good transmission cooler. Assuming a full power time of 50% you'll average 250hp through the transmission vs the 100-odd hp that's at the upper end of what a sedan ever uses on the road (Even towing a car trailer up a steep hill, a sedan will seldom use more than 100hp for any length of time).

Can your engine management system do torque reduction on shift? As well as reducing mechanical load on the parts, a shift absorbs the difference in power between the two rpm points *entirely as heat for the duration of the shift* so reducing torque on shifts brings rpm down faster for a shorter shift duration and reduces the heat generation significantly. Plus it sounds cool like a DSG engine shifting

[Rob-bb]

What's the oil pump housing and pickup like?

I'd imagine that there are gains to be had in cleaning up edges of machined surfaces, castings etc. Make sure the pickup is correctly sized for the new application (can't help you with the sizing, I just know you've changed the pump speed by about 35%).

Cavitation is as much about restriction on the inlet as it is pump design.

Converter on a circuit track car? I hope you have a comically good transmission cooler. Assuming a full power time of 50% you'll average 250hp through the transmission vs the 100-odd hp that's at the upper end of what a sedan ever uses on the road (Even towing a car trailer up a steep hill, a sedan will seldom use more than 100hp for any length of time)

Yes, everyone seems to not like that idea, the transmission will be rebuilt and has adequate cooling with it's own fan, the stock trans has been fine so far (with additional cooling beyond the factory setup). But I am not doing massive time, just 10 minute sessions, and for fun, track days and things like that. I don't want to move to a manual as I have an old knee injury which makes it difficult to use and can make it impossible at times

The oil pump and pickup I haven't had a look at yet, I have the engine on a stand and am just starting to strip it down, the manual makes it look like a typical pump mounted on the crankshaft, with this sort of internal setup


So, if I enlarge the pickup diameter will there be any side effects? Will it struggle with suction to fill the pump at lower speeds?

[lefty o]

good fasteners. best rod bolts you can find, and good head studs.

[BLSTIC]

I seriously doubt it, vacuum at the pump is affected by flow rate (restriction) and vertical head distance, not head volume.

What you *might* see is a longer time to initially fill the tube from empty, but I don't know if that's actually a significant factor in oil starvation (it could be that the pump takes 5 rotations to self prime with a narrow feed and 8 with a larger diameter, but the average oil surge lasts 50 rotations anyway. Please if that's a concern do your own math on that or ask someone else, those numbers are straight up pulled from nowhere).

I don't mind an auto on the track, you just have to be certain it's not overheating. It's not like you are in a spec class where everyone runs the same thing and 10hp and 40kg is serious business. And for a street car a racing style clutch and flywheel makes reverse parallel parking a right PITA.

[dannobee]

Redline is often dictated by the cam and valvetrain, not the lower end. Make sure to get the lightest valvetrain components possible and talk to your cam supplier to make sure your cams won't float the valves at 7501rpm.

[Rob-bb]

Redline is often dictated by the cam and valvetrain, not the lower end. Make sure to get the lightest valvetrain components possible and talk to your cam supplier to make sure your cams won't float the valves at 7501rpm.

This I have covered, the profile and springs and the rest are designed for this range, some head work to be done still.

[Rob-bb]

What you *might* see is a longer time to initially fill the tube from empty, but I don't know if that's actually a significant factor in oil starvation (it could be that the pump takes 5 rotations to self prime with a narrow feed and 8 with a larger diameter, but the average oil surge lasts 50 rotations anyway. Please if that's a concern do your own math on that or ask someone else, those numbers are straight up pulled from nowhere).

Thanks for that info, I am not worried about exact numbers and math at this stage, I am looking for info to plan the work to be done. This a great example, I would not have considered the oil pump pickup at all if you guys hadn't mentioned it. I can worry about the actual numbers when it comes time to do the work

I will also be adding something like an accusump, adn will look into baffles in the oil tray once I have it off and can see what is already there

[Rob-bb]

Can your engine management system do torque reduction on shift? As well as reducing mechanical load on the parts, a shift absorbs the difference in power between the two rpm points *entirely as heat for the duration of the shift* so reducing torque on shifts brings rpm down faster for a shorter shift duration and reduces the heat generation significantly. Plus it sounds cool like a DSG engine shifting

The ECU does rev matching on downshifts, I'll have to look into it to see if it does anything to reduce torque on a shift

EDIT: yes, it does reduce torque on shift assuming the "garbage in, garbage out'" philosophy is understood and the transmission and throttle data tables are properly adjusted

[stealth]

First on the list should be a well respected engine builder familiar with that engine.

Finding someone with Special knowledge of the details of that engine platform Is key. Each engine family has certain quirks and areas that need improvement over others. Someone to guide your budget to best address the strong and weak areas is a wise investment.

[Rob-bb]

First on the list should be a well respected engine builder familiar with that engine.

The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man.

that seems... reasonable

[nhrastocker]

https://www.gibsontech.co.uk/engines/vk45de-4-5-litre