Precision 5858 on stock head (Gen 1)

Hi all, so I'm planning on picking a second hand ball bearing 5858, .64A/R, complete with manifold, gate and dump for my racecar. I know the previous owner, it's all legit, no wear etc, it's practically new. To be honest though, if I was buying a new turbo, I would not go for the 5858 as I think it'll be too big and I'm concerned about response. But, it came up for sale, so..

Question time. Block and manifolds is Gen 2. Head and cams are gen 1 3sge. Sump is Gen 3. 1ZZ coil on plug. Pistons and rods are forged Arias. ACL race bearings, ARP head studs, cometic hg, walbro 460 fuel pump, 1000cc injectors, e85, haltech engine management. Turbo is currently a ct20b, at 19psi it makes 191kW at the wheels.

Studying my logs, even at the slower corners, my rpm drops to around 4k. Being a racecar it's always going to live in this upper rev range.

Opinions welcome. Will I regret this? Rememeber, this is a racecar only,(time attack) no street duties

I'm no turbo expert but my gut feeling says it's going to be a little laggy.

I've got a 50 trim (46mm), .63 ar Garret and I'm not hitting full boost till 3500ish.

It may work out for you since you are going to be at 4k+ most of the time.

My question for you before delving into turbo talk, why are you running a Gen 1 head? Why not Gen 2 head with Gen 3 cams? Why go backwards? But if it works, it works. More on that later.

I've been looking at the Precision 5858 BB for quite some time for one of my projects (Alltrac with Gen 3 built motor), so this will be more of an observation of your experience vs advice. Magroo is right. If you're living above 4k rpms, you may be ok.

Keep us updated.

GT4times2":2qged0mc said:

My question for you before delving into turbo talk, why are you running a Gen 1 head? Why not Gen 2 head with Gen 3 cams? Why go backwards? But if it works, it works. More on that later.

I've been looking at the Precision 5858 BB for quite some time for one of my projects (Alltrac with Gen 3 built motor), so this will be more of an observation of your experience vs advice. Magroo is right. If you're living above 4k rpms, you may be ok.

Keep us updated.

Click to expand...

When I bought the car some 10+ years ago, that's how it came. Back then I had no idea at all about the different generations. I'd say the head failed and they sourced that one. It's been pretty good in some respects though - top feed rail from factory lol.

Over the years as I've learned more and more about it and started racing, I've been Frankensteining the engine. Gen 3 sump and oil pump, ct20b, coil on plug, electric water pump etc. It's been a fantastic learning project and great experience.

But yeah, the idea is to get it running with this turbo for next season, see how it goes, but I fully intend on building a whole new engine at some stage - with all the experience I have now I know exactly what I want.

Punknoodle":10pb9mp7 said:

GT4times2":10pb9mp7 said:

My question for you before delving into turbo talk, why are you running a Gen 1 head? Why not Gen 2 head with Gen 3 cams? Why go backwards? But if it works, it works. More on that later.

I've been looking at the Precision 5858 BB for quite some time for one of my projects (Alltrac with Gen 3 built motor), so this will be more of an observation of your experience vs advice. Magroo is right. If you're living above 4k rpms, you may be ok.

Keep us updated.

Click to expand...

When I bought the car some 10+ years ago, that's how it came. Back then I had no idea at all about the different generations. I'd say the head failed and they sourced that one. It's been pretty good in some respects though - top feed rail from factory lol.

Over the years as I've learned more and more about it and started racing, I've been Frankensteining the engine. Gen 3 sump and oil pump, ct20b, coil on plug, electric water pump etc. It's been a fantastic learning project and great experience.

But yeah, the idea is to get it running with this turbo for next season, see how it goes, but I fully intend on building a whole new engine at some stage - with all the experience I have now I know exactly what I want.

Click to expand...

Interesting set up. Please share the goods. I've been watching your build in the Projects section. I didn't know it was Gen 1 head. I have a ST185 like yours, same color and all. Just with a Gen4 swap. I've stalled starting a thread of my Alltracs. Too many pics and they're all over the place. Again, please share your experience with the 5858. I'd love to hear your feedback.

GT4times2":2x7z6wxl said:

Punknoodle":2x7z6wxl said:

GT4times2":2x7z6wxl said:

My question for you before delving into turbo talk, why are you running a Gen 1 head? Why not Gen 2 head with Gen 3 cams? Why go backwards? But if it works, it works. More on that later.

I've been looking at the Precision 5858 BB for quite some time for one of my projects (Alltrac with Gen 3 built motor), so this will be more of an observation of your experience vs advice. Magroo is right. If you're living above 4k rpms, you may be ok.

Keep us updated.

Click to expand...

When I bought the car some 10+ years ago, that's how it came. Back then I had no idea at all about the different generations. I'd say the head failed and they sourced that one. It's been pretty good in some respects though - top feed rail from factory lol.

Over the years as I've learned more and more about it and started racing, I've been Frankensteining the engine. Gen 3 sump and oil pump, ct20b, coil on plug, electric water pump etc. It's been a fantastic learning project and great experience.

But yeah, the idea is to get it running with this turbo for next season, see how it goes, but I fully intend on building a whole new engine at some stage - with all the experience I have now I know exactly what I want.

Click to expand...

Interesting set up. Please share the goods. I've been watching your build in the Projects section. I didn't know it was Gen 1 head. I have a ST185 like yours, same color and all. Just with a Gen4 swap. I've stalled starting a thread of my Alltracs. Too many pics and they're all over the place. Again, please share your experience with the 5858. I'd love to hear your feedback.

Click to expand...

Ah, I've stopped updating forum posts as it's gone kinda dead.. I only really post regularly on insta @thedukeofwinsor or my facebook page Duke's Racecar Engineering..
29th Sept - King of Qr Time Attack 2018 - (1847)-(ZF-0327-13275-1-001) by Nick Winsor, on Flickr

Really nice!!! :notworthy: :notworthy:

I don't dwell on SM though. I can visit, but I don't have SM pages/accounts etc to share or comment/follow etc. Sad to see this forum into a ghost town. :shrug:

GT4times2":1nw1qwbi said:

Really nice!!! :notworthy: :notworthy:

I don't dwell on SM though. I can visit, but I don't have SM pages/accounts etc to share or comment/follow etc. Sad to see this forum into a ghost town. :shrug:

Click to expand...

Don't get me wrong, if peoole are interested I'll update it, but yeah generally exactly that man, there just any engagement any more so it feels like you are just writing entries in a diary rather than creating conversation.

Punknoodle":16q9lml6 said:

GT4times2":16q9lml6 said:

Really nice!!! :notworthy: :notworthy:

I don't dwell on SM though. I can visit, but I don't have SM pages/accounts etc to share or comment/follow etc. Sad to see this forum into a ghost town. :shrug:

Click to expand...

Don't get me wrong, if peoole are interested I'll update it, but yeah generally exactly that man, there just any engagement any more so it feels like you are just writing entries in a diary rather than creating conversation.

Click to expand...

Please do update us with your progress. I check here more than i would any SM. Lmao @ diary entry.

GT4times2":7s8fvj8n said:

Punknoodle":7s8fvj8n said:

GT4times2":7s8fvj8n said:

Really nice!!! :notworthy: :notworthy:

I don't dwell on SM though. I can visit, but I don't have SM pages/accounts etc to share or comment/follow etc. Sad to see this forum into a ghost town. :shrug:

Click to expand...

Don't get me wrong, if peoole are interested I'll update it, but yeah generally exactly that man, there just any engagement any more so it feels like you are just writing entries in a diary rather than creating conversation.

Click to expand...

Please do update us with your progress. I check here more than i would any SM. Lmao @ diary entry.

Click to expand...

Ok, done

Ok. Great!!